reverted last commit

git-svn-id: http://svn.miranda-ng.org/main/trunk@16281 1316c22d-e87f-b044-9b9b-93d7a3e3ba9c

4 files changed, 702 insertions, 1111 deletions

diff --git a/plugins/Dbx_mdb/src/lmdb/lmdb.h b/plugins/Dbx_mdb/src/lmdb/lmdb.h
index c4d05d1791..f318ad416d 100644
--- a/plugins/Dbx_mdb/src/lmdb/lmdb.h
+++ b/plugins/Dbx_mdb/src/lmdb/lmdb.h
@@ -40,9 +40,6 @@
  *	corrupt the database. Of course if your application code is known to
  *	be bug-free (...) then this is not an issue.
  *
- *	If this is your first time using a transactional embedded key/value
- *	store, you may find the \ref starting page to be helpful.
- *
  *	@section caveats_sec Caveats
  *	Troubleshooting the lock file, plus semaphores on BSD systems:
  *
@@ -53,14 +50,14 @@
  *
  *	  Fix: Check for stale readers periodically, using the
  *	  #mdb_reader_check function or the \ref mdb_stat_1 "mdb_stat" tool.
- *	  Stale writers will be cleared automatically on some systems:
+ *	  Stale writers will be cleared automatically on most systems:
  *	  - Windows - automatic
+ *	  - BSD, systems using SysV semaphores - automatic
  *	  - Linux, systems using POSIX mutexes with Robust option - automatic
- *	  - not on BSD, systems using POSIX semaphores.
  *	  Otherwise just make all programs using the database close it;
  *	  the lockfile is always reset on first open of the environment.
  *
- *	- On BSD systems or others configured with MDB_USE_POSIX_SEM,
+ *	- On BSD systems or others configured with MDB_USE_SYSV_SEM,
  *	  startup can fail due to semaphores owned by another userid.
  *
  *	  Fix: Open and close the database as the user which owns the
@@ -112,9 +109,7 @@
  *	  The transaction becomes "long-lived" as above until a check
  *	  for stale readers is performed or the lockfile is reset,
  *	  since the process may not remove it from the lockfile.
- *
- *	  This does not apply to write transactions if the system clears
- *	  stale writers, see above.
+ *	  Except write-transactions on Unix with MDB_ROBUST or on Windows.
  *
  *	- If you do that anyway, do a periodic check for stale readers. Or
  *	  close the environment once in a while, so the lockfile can get reset.
@@ -129,7 +124,7 @@
  *
  *	@author	Howard Chu, Symas Corporation.
  *
- *	@copyright Copyright 2011-2016 Howard Chu, Symas Corp. All rights reserved.
+ *	@copyright Copyright 2011-2014 Howard Chu, Symas Corp. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted only as authorized by the OpenLDAP
@@ -194,7 +189,7 @@ typedef int mdb_filehandle_t;
 /** Library minor version */
 #define MDB_VERSION_MINOR	9
 /** Library patch version */
-#define MDB_VERSION_PATCH	18
+#define MDB_VERSION_PATCH	14
 
 /** Combine args a,b,c into a single integer for easy version comparisons */
 #define MDB_VERINT(a,b,c)	(((a) << 24) | ((b) << 16) | (c))
@@ -204,7 +199,7 @@ typedef int mdb_filehandle_t;
 	MDB_VERINT(MDB_VERSION_MAJOR,MDB_VERSION_MINOR,MDB_VERSION_PATCH)
 
 /** The release date of this library version */
-#define MDB_VERSION_DATE	"February 5, 2016"
+#define MDB_VERSION_DATE	"September 20, 2014"
 
 /** A stringifier for the version info */
 #define MDB_VERSTR(a,b,c,d)	"LMDB " #a "." #b "." #c ": (" d ")"
@@ -306,12 +301,12 @@ typedef void (MDB_rel_func)(MDB_val *item, void *oldptr, void *newptr, void *rel
 #define MDB_REVERSEKEY	0x02
 	/** use sorted duplicates */
 #define MDB_DUPSORT		0x04
-	/** numeric keys in native byte order: either unsigned int or size_t.
+	/** numeric keys in native byte order.
 	 *  The keys must all be of the same size. */
 #define MDB_INTEGERKEY	0x08
 	/** with #MDB_DUPSORT, sorted dup items have fixed size */
 #define MDB_DUPFIXED	0x10
-	/** with #MDB_DUPSORT, dups are #MDB_INTEGERKEY-style integers */
+	/** with #MDB_DUPSORT, dups are numeric in native byte order */
 #define MDB_INTEGERDUP	0x20
 	/** with #MDB_DUPSORT, use reverse string dups */
 #define MDB_REVERSEDUP	0x40
@@ -423,18 +418,11 @@ typedef enum MDB_cursor_op {
 #define MDB_PAGE_FULL	(-30786)
 	/** Database contents grew beyond environment mapsize */
 #define MDB_MAP_RESIZED	(-30785)
-	/** Operation and DB incompatible, or DB type changed. This can mean:
-	 *	<ul>
-	 *	<li>The operation expects an #MDB_DUPSORT / #MDB_DUPFIXED database.
-	 *	<li>Opening a named DB when the unnamed DB has #MDB_DUPSORT / #MDB_INTEGERKEY.
-	 *	<li>Accessing a data record as a database, or vice versa.
-	 *	<li>The database was dropped and recreated with different flags.
-	 *	</ul>
-	 */
+	/** MDB_INCOMPATIBLE: Operation and DB incompatible, or DB flags changed */
 #define MDB_INCOMPATIBLE	(-30784)
 	/** Invalid reuse of reader locktable slot */
 #define MDB_BAD_RSLOT		(-30783)
-	/** Transaction must abort, has a child, or is invalid */
+	/** Transaction cannot recover - it must be aborted */
 #define MDB_BAD_TXN			(-30782)
 	/** Unsupported size of key/DB name/data, or wrong DUPFIXED size */
 #define MDB_BAD_VALSIZE		(-30781)
@@ -460,7 +448,7 @@ typedef struct MDB_envinfo {
 	void	*me_mapaddr;			/**< Address of map, if fixed */
 	size_t	me_mapsize;				/**< Size of the data memory map */
 	size_t	me_last_pgno;			/**< ID of the last used page */
-	size_t	me_last_txnid;			/**< ID of the last committed transaction */
+	size_t  me_last_txnid;		/**< ID of the last committed transaction */
 	unsigned int me_maxreaders;		/**< max reader slots in the environment */
 	unsigned int me_numreaders;		/**< max reader slots used in the environment */
 } MDB_envinfo;
@@ -529,14 +517,12 @@ int  mdb_env_create(MDB_env **env);
 	 *		allowed. LMDB will still modify the lock file - except on read-only
 	 *		filesystems, where LMDB does not use locks.
 	 *	<li>#MDB_WRITEMAP
-	 *		Use a writeable memory map unless MDB_RDONLY is set. This uses
-	 *		fewer mallocs but loses protection from application bugs
+	 *		Use a writeable memory map unless MDB_RDONLY is set. This is faster
+	 *		and uses fewer mallocs, but loses protection from application bugs
 	 *		like wild pointer writes and other bad updates into the database.
-	 *		This may be slightly faster for DBs that fit entirely in RAM, but
-	 *		is slower for DBs larger than RAM.
 	 *		Incompatible with nested transactions.
-	 *		Do not mix processes with and without MDB_WRITEMAP on the same
-	 *		environment.  This can defeat durability (#mdb_env_sync etc).
+	 *		Processes with and without MDB_WRITEMAP on the same environment do
+	 *		not cooperate well.
 	 *	<li>#MDB_NOMETASYNC
 	 *		Flush system buffers to disk only once per transaction, omit the
 	 *		metadata flush. Defer that until the system flushes files to disk,
@@ -607,8 +593,8 @@ int  mdb_env_create(MDB_env **env);
 	 *		reserved in that case.
 	 *		This flag may be changed at any time using #mdb_env_set_flags().
 	 * </ul>
-	 * @param[in] mode The UNIX permissions to set on created files and semaphores.
-	 * This parameter is ignored on Windows.
+	 * @param[in] mode The UNIX permissions to set on created files. This parameter
+	 * is ignored on Windows.
 	 * @return A non-zero error value on failure and 0 on success. Some possible
 	 * errors are:
 	 * <ul>
@@ -717,8 +703,7 @@ int  mdb_env_info(MDB_env *env, MDB_envinfo *stat);
 	 * Data is always written to disk when #mdb_txn_commit() is called,
 	 * but the operating system may keep it buffered. LMDB always flushes
 	 * the OS buffers upon commit as well, unless the environment was
-	 * opened with #MDB_NOSYNC or in part #MDB_NOMETASYNC. This call is
-	 * not valid if the environment was opened with #MDB_RDONLY.
+	 * opened with #MDB_NOSYNC or in part #MDB_NOMETASYNC.
 	 * @param[in] env An environment handle returned by #mdb_env_create()
 	 * @param[in] force If non-zero, force a synchronous flush.  Otherwise
 	 *  if the environment has the #MDB_NOSYNC flag set the flushes
@@ -726,7 +711,6 @@ int  mdb_env_info(MDB_env *env, MDB_envinfo *stat);
 	 * @return A non-zero error value on failure and 0 on success. Some possible
 	 * errors are:
 	 * <ul>
-	 *	<li>EACCES - the environment is read-only.
 	 *	<li>EINVAL - an invalid parameter was specified.
 	 *	<li>EIO - an error occurred during synchronization.
 	 * </ul>
@@ -748,6 +732,7 @@ void mdb_env_close(MDB_env *env);
 	 * This may be used to set some flags in addition to those from
 	 * #mdb_env_open(), or to unset these flags.  If several threads
 	 * change the flags at the same time, the result is undefined.
+	 * Most flags cannot be changed after #mdb_env_open().
 	 * @param[in] env An environment handle returned by #mdb_env_create()
 	 * @param[in] flags The flags to change, bitwise OR'ed together
 	 * @param[in] onoff A non-zero value sets the flags, zero clears them.
@@ -1051,22 +1036,19 @@ int  mdb_txn_renew(MDB_txn *txn);
 	 * The database handle may be discarded by calling #mdb_dbi_close().
 	 * The old database handle is returned if the database was already open.
 	 * The handle may only be closed once.
-	 *
 	 * The database handle will be private to the current transaction until
 	 * the transaction is successfully committed. If the transaction is
 	 * aborted the handle will be closed automatically.
-	 * After a successful commit the handle will reside in the shared
-	 * environment, and may be used by other transactions.
-	 *
-	 * This function must not be called from multiple concurrent
-	 * transactions in the same process. A transaction that uses
-	 * this function must finish (either commit or abort) before
+	 * After a successful commit the
+	 * handle will reside in the shared environment, and may be used
+	 * by other transactions. This function must not be called from
+	 * multiple concurrent transactions in the same process. A transaction
+	 * that uses this function must finish (either commit or abort) before
 	 * any other transaction in the process may use this function.
 	 *
 	 * To use named databases (with name != NULL), #mdb_env_set_maxdbs()
-	 * must be called before opening the environment.  Database names are
-	 * keys in the unnamed database, and may be read but not written.
-	 *
+	 * must be called before opening the environment.  Database names
+	 * are kept as keys in the unnamed database.
 	 * @param[in] txn A transaction handle returned by #mdb_txn_begin()
 	 * @param[in] name The name of the database to open. If only a single
 	 * 	database is needed in the environment, this value may be NULL.
@@ -1083,9 +1065,9 @@ int  mdb_txn_renew(MDB_txn *txn);
 	 *		keys may have multiple data items, stored in sorted order.) By default
 	 *		keys must be unique and may have only a single data item.
 	 *	<li>#MDB_INTEGERKEY
-	 *		Keys are binary integers in native byte order, either unsigned int
-	 *		or size_t, and will be sorted as such.
-	 *		The keys must all be of the same size.
+	 *		Keys are binary integers in native byte order. Setting this option
+	 *		requires all keys to be the same size, typically sizeof(int)
+	 *		or sizeof(size_t).
 	 *	<li>#MDB_DUPFIXED
 	 *		This flag may only be used in combination with #MDB_DUPSORT. This option
 	 *		tells the library that the data items for this database are all the same
@@ -1093,8 +1075,8 @@ int  mdb_txn_renew(MDB_txn *txn);
 	 *		all data items are the same size, the #MDB_GET_MULTIPLE and #MDB_NEXT_MULTIPLE
 	 *		cursor operations may be used to retrieve multiple items at once.
 	 *	<li>#MDB_INTEGERDUP
-	 *		This option specifies that duplicate data items are binary integers,
-	 *		similar to #MDB_INTEGERKEY keys.
+	 *		This option specifies that duplicate data items are also integers, and
+	 *		should be sorted as such.
 	 *	<li>#MDB_REVERSEDUP
 	 *		This option specifies that duplicate data items should be compared as
 	 *		strings in reverse order.
@@ -1303,8 +1285,7 @@ int  mdb_get(MDB_txn *txn, MDB_dbi dbi, MDB_val *key, MDB_val *data);
 	 *		the next update operation or the transaction ends. This saves
 	 *		an extra memcpy if the data is being generated later.
 	 *		LMDB does nothing else with this memory, the caller is expected
-	 *		to modify all of the space requested. This flag must not be
-	 *		specified if the database was opened with #MDB_DUPSORT.
+	 *		to modify all of the space requested.
 	 *	<li>#MDB_APPEND - append the given key/data pair to the end of the
 	 *		database. This option allows fast bulk loading when keys are
 	 *		already known to be in the correct order. Loading unsorted keys
@@ -1460,15 +1441,13 @@ int  mdb_cursor_get(MDB_cursor *cursor, MDB_val *key, MDB_val *data,
 	 *		the database supports duplicates (#MDB_DUPSORT).
 	 *	<li>#MDB_RESERVE - reserve space for data of the given size, but
 	 *		don't copy the given data. Instead, return a pointer to the
-	 *		reserved space, which the caller can fill in later - before
-	 *		the next update operation or the transaction ends. This saves
-	 *		an extra memcpy if the data is being generated later. This flag
-	 *		must not be specified if the database was opened with #MDB_DUPSORT.
+	 *		reserved space, which the caller can fill in later. This saves
+	 *		an extra memcpy if the data is being generated later.
 	 *	<li>#MDB_APPEND - append the given key/data pair to the end of the
 	 *		database. No key comparisons are performed. This option allows
 	 *		fast bulk loading when keys are already known to be in the
 	 *		correct order. Loading unsorted keys with this flag will cause
-	 *		a #MDB_KEYEXIST error.
+	 *		data corruption.
 	 *	<li>#MDB_APPENDDUP - as above, but for sorted dup data.
 	 *	<li>#MDB_MULTIPLE - store multiple contiguous data elements in a
 	 *		single request. This flag may only be specified if the database
@@ -1486,7 +1465,7 @@ int  mdb_cursor_get(MDB_cursor *cursor, MDB_val *key, MDB_val *data,
 	 * <ul>
 	 *	<li>#MDB_MAP_FULL - the database is full, see #mdb_env_set_mapsize().
 	 *	<li>#MDB_TXN_FULL - the transaction has too many dirty pages.
-	 *	<li>EACCES - an attempt was made to write in a read-only transaction.
+	 *	<li>EACCES - an attempt was made to modify a read-only database.
 	 *	<li>EINVAL - an invalid parameter was specified.
 	 * </ul>
 	 */
@@ -1506,7 +1485,7 @@ int  mdb_cursor_put(MDB_cursor *cursor, MDB_val *key, MDB_val *data,
 	 * @return A non-zero error value on failure and 0 on success. Some possible
 	 * errors are:
 	 * <ul>
-	 *	<li>EACCES - an attempt was made to write in a read-only transaction.
+	 *	<li>EACCES - an attempt was made to modify a read-only database.
 	 *	<li>EINVAL - an invalid parameter was specified.
 	 * </ul>
 	 */
diff --git a/plugins/Dbx_mdb/src/lmdb/mdb.c b/plugins/Dbx_mdb/src/lmdb/mdb.c
index d2e81e4e9c..2b0bad3dd1 100644
--- a/plugins/Dbx_mdb/src/lmdb/mdb.c
+++ b/plugins/Dbx_mdb/src/lmdb/mdb.c
@@ -5,7 +5,7 @@
  *	BerkeleyDB API, but much simplified.
  */
 /*
- * Copyright 2011-2016 Howard Chu, Symas Corp.
+ * Copyright 2011-2014 Howard Chu, Symas Corp.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -42,6 +42,12 @@
  *  as int64 which is wrong. MSVC doesn't define it at all, so just
  *  don't use it.
  */
+#ifdef _WIN64
+typedef signed __int64 ssize_t;
+#else
+typedef signed int ssize_t;
+#endif
+
 #define MDB_PID_T	int
 #define MDB_THR_T	DWORD
 #include <sys/types.h>
@@ -85,25 +91,17 @@ extern int cacheflush(char *addr, int nbytes, int cache);
  *	define MDB_FDATASYNC_WORKS if this code will only be run
  *	on kernels 3.6 and newer.
  */
-#define	BROKEN_FDATASYNC
+//#define BROKEN_FDATASYNC
 #endif
 
 #include <errno.h>
 #include <limits.h>
 #include <stddef.h>
-#include <inttypes.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
 
-#ifdef _MSC_VER
-#include <io.h>
-typedef SSIZE_T	ssize_t;
-#else
-#include <unistd.h>
-#endif
-
 #if defined(__sun) || defined(ANDROID)
 /* Most platforms have posix_memalign, older may only have memalign */
 #define HAVE_MEMALIGN	1
@@ -116,7 +114,7 @@ typedef SSIZE_T	ssize_t;
 #endif
 
 #if defined(__APPLE__) || defined (BSD)
-# define MDB_USE_POSIX_SEM	1
+# define MDB_USE_SYSV_SEM	1
 # define MDB_FDATASYNC		fsync
 #elif defined(ANDROID)
 # define MDB_FDATASYNC		fsync
@@ -124,18 +122,18 @@ typedef SSIZE_T	ssize_t;
 
 #ifndef _WIN32
 #include <pthread.h>
-#ifdef MDB_USE_POSIX_SEM
-# define MDB_USE_HASH		1
-#include <semaphore.h>
-#else
-#define MDB_USE_POSIX_MUTEX	1
-#endif
-#endif
-
-#if defined(_WIN32) + defined(MDB_USE_POSIX_SEM) \
-	+ defined(MDB_USE_POSIX_MUTEX) != 1
-# error "Ambiguous shared-lock implementation"
-#endif
+#ifdef MDB_USE_SYSV_SEM
+#include <sys/ipc.h>
+#include <sys/sem.h>
+#ifdef _SEM_SEMUN_UNDEFINED
+union semun {
+	int val;
+	struct semid_ds *buf;
+	unsigned short *array;
+};
+#endif /* _SEM_SEMUN_UNDEFINED */
+#endif /* MDB_USE_SYSV_SEM */
+#endif /* !_WIN32 */
 
 #ifdef USE_VALGRIND
 #include <valgrind/memcheck.h>
@@ -198,12 +196,6 @@ typedef SSIZE_T	ssize_t;
 #define ESECT
 #endif
 
-#ifdef _WIN32
-#define CALL_CONV WINAPI
-#else
-#define CALL_CONV
-#endif
-
 /** @defgroup internal	LMDB Internals
  *	@{
  */
@@ -220,6 +212,10 @@ typedef SSIZE_T	ssize_t;
 #define MDB_DEVEL 0
 #endif
 
+#if defined(_WIN32) || (defined(EOWNERDEAD) && !defined(MDB_USE_SYSV_SEM))
+#define MDB_ROBUST_SUPPORTED	1
+#endif
+
 	/** Wrapper around __func__, which is a C99 feature */
 #if __STDC_VERSION__ >= 199901L
 # define mdb_func_	__func__
@@ -230,53 +226,14 @@ typedef SSIZE_T	ssize_t;
 # define mdb_func_	"<mdb_unknown>"
 #endif
 
-/* Internal error codes, not exposed outside liblmdb */
-#define	MDB_NO_ROOT		(MDB_LAST_ERRCODE + 10)
-#ifdef _WIN32
-#define MDB_OWNERDEAD	((int) WAIT_ABANDONED)
-#elif defined(MDB_USE_POSIX_MUTEX) && defined(EOWNERDEAD)
-#define MDB_OWNERDEAD	EOWNERDEAD	/**< #LOCK_MUTEX0() result if dead owner */
-#endif
-
-#ifdef __GLIBC__
-#define	GLIBC_VER	((__GLIBC__ << 16 )| __GLIBC_MINOR__)
-#endif
-/** Some platforms define the EOWNERDEAD error code
- * even though they don't support Robust Mutexes.
- * Compile with -DMDB_USE_ROBUST=0, or use some other
- * mechanism like -DMDB_USE_SYSV_SEM instead of
- * -DMDB_USE_POSIX_MUTEX. (SysV semaphores are
- * also Robust, but some systems don't support them
- * either.)
- */
-#ifndef MDB_USE_ROBUST
-/* Android currently lacks Robust Mutex support. So does glibc < 2.4. */
-# if defined(MDB_USE_POSIX_MUTEX) && (defined(ANDROID) || \
-	(defined(__GLIBC__) && GLIBC_VER < 0x020004))
-#  define MDB_USE_ROBUST	0
-# else
-#  define MDB_USE_ROBUST	1
-/* glibc < 2.12 only provided _np API */
-#  if defined(__GLIBC__) && GLIBC_VER < 0x02000c
-#   define PTHREAD_MUTEX_ROBUST	PTHREAD_MUTEX_ROBUST_NP
-#   define pthread_mutexattr_setrobust(attr, flag)	pthread_mutexattr_setrobust_np(attr, flag)
-#   define pthread_mutex_consistent(mutex)	pthread_mutex_consistent_np(mutex)
-#  endif
-# endif
-#endif /* MDB_USE_ROBUST */
-
-#if defined(MDB_OWNERDEAD) && MDB_USE_ROBUST
-#define MDB_ROBUST_SUPPORTED	1
-#endif
-
 #ifdef _WIN32
 #define MDB_USE_HASH	1
 #define MDB_PIDLOCK	0
-#define THREAD_RET	DWORD
+#define THREAD_RET	DWORD WINAPI
 #define pthread_t	HANDLE
 #define pthread_mutex_t	HANDLE
 #define pthread_cond_t	HANDLE
-typedef HANDLE mdb_mutex_t, mdb_mutexref_t;
+typedef HANDLE mdb_mutex_t;
 #define pthread_key_t	DWORD
 #define pthread_self()	GetCurrentThreadId()
 #define pthread_key_create(x,y)	\
@@ -284,15 +241,16 @@ typedef HANDLE mdb_mutex_t, mdb_mutexref_t;
 #define pthread_key_delete(x)	TlsFree(x)
 #define pthread_getspecific(x)	TlsGetValue(x)
 #define pthread_setspecific(x,y)	(TlsSetValue(x,y) ? 0 : ErrCode())
+#define pthread_mutex_consistent(mutex) 0
 #define pthread_mutex_unlock(x)	ReleaseMutex(*x)
 #define pthread_mutex_lock(x)	WaitForSingleObject(*x, INFINITE)
 #define pthread_cond_signal(x)	SetEvent(*x)
 #define pthread_cond_wait(cond,mutex)	do{SignalObjectAndWait(*mutex, *cond, INFINITE, FALSE); WaitForSingleObject(*mutex, INFINITE);}while(0)
 #define THREAD_CREATE(thr,start,arg)	thr=CreateThread(NULL,0,start,arg,0,NULL)
 #define THREAD_FINISH(thr)	WaitForSingleObject(thr, INFINITE)
+#define MDB_MUTEX(env, rw)		((env)->me_##rw##mutex)
 #define LOCK_MUTEX0(mutex)		WaitForSingleObject(mutex, INFINITE)
 #define UNLOCK_MUTEX(mutex)		ReleaseMutex(mutex)
-#define mdb_mutex_consistent(mutex)	0
 #define getpid()	GetCurrentProcessId()
 #define	MDB_FDATASYNC(fd)	(!FlushFileBuffers(fd))
 #define	MDB_MSYNC(addr,len,flags)	(!FlushViewOfFile(addr,len))
@@ -315,30 +273,38 @@ typedef HANDLE mdb_mutex_t, mdb_mutexref_t;
 	/** For MDB_LOCK_FORMAT: True if readers take a pid lock in the lockfile */
 #define MDB_PIDLOCK			1
 
-#ifdef MDB_USE_POSIX_SEM
+#ifdef MDB_USE_SYSV_SEM
 
-typedef sem_t *mdb_mutex_t, *mdb_mutexref_t;
+typedef struct mdb_mutex {
+	int semid;
+	int semnum;
+} mdb_mutex_t;
+
+#define MDB_MUTEX(env, rw)		(&(env)->me_##rw##mutex)
 #define LOCK_MUTEX0(mutex)		mdb_sem_wait(mutex)
-#define UNLOCK_MUTEX(mutex)		sem_post(mutex)
+#define UNLOCK_MUTEX(mutex)		do { \
+	struct sembuf sb = { 0, 1, SEM_UNDO }; \
+	sb.sem_num = (mutex)->semnum; \
+	semop((mutex)->semid, &sb, 1); \
+} while(0)
 
 static int
-mdb_sem_wait(sem_t *sem)
+mdb_sem_wait(mdb_mutex_t *sem)
 {
    int rc;
-   while ((rc = sem_wait(sem)) && (rc = errno) == EINTR) ;
+   struct sembuf sb = { 0, -1, SEM_UNDO };
+   sb.sem_num = sem->semnum;
+   while ((rc = semop(sem->semid, &sb, 1)) && (rc = errno) == EINTR) ;
    return rc;
 }
 
-#else	/* MDB_USE_POSIX_MUTEX: */
-	/** Shared mutex/semaphore as it is stored (mdb_mutex_t), and as
-	 *	local variables keep it (mdb_mutexref_t).
-	 *
-	 *	When #mdb_mutexref_t is a pointer declaration and #mdb_mutex_t is
-	 *	not, then it is array[size 1] so it can be assigned to a pointer.
-	 *	@{
+#else
+	/** Pointer/HANDLE type of shared mutex/semaphore.
 	 */
-typedef pthread_mutex_t mdb_mutex_t[1], *mdb_mutexref_t;
-	/*	@} */
+typedef pthread_mutex_t mdb_mutex_t;
+	/** Mutex for the reader table (rw = r) or write transaction (rw = w).
+	 */
+#define MDB_MUTEX(env, rw)	(&(env)->me_txns->mti_##rw##mutex)
 	/** Lock the reader or writer mutex.
 	 *	Returns 0 or a code to give #mdb_mutex_failed(), as in #LOCK_MUTEX().
 	 */
@@ -346,10 +312,7 @@ typedef pthread_mutex_t mdb_mutex_t[1], *mdb_mutexref_t;
 	/** Unlock the reader or writer mutex.
 	 */
 #define UNLOCK_MUTEX(mutex)	pthread_mutex_unlock(mutex)
-	/** Mark mutex-protected data as repaired, after death of previous owner.
-	 */
-#define mdb_mutex_consistent(mutex)	pthread_mutex_consistent(mutex)
-#endif	/* MDB_USE_POSIX_SEM */
+#endif	/* MDB_USE_SYSV_SEM */
 
 	/** Get the error code for the last failed system function.
 	 */
@@ -374,8 +337,10 @@ typedef pthread_mutex_t mdb_mutex_t[1], *mdb_mutexref_t;
 #define	GET_PAGESIZE(x)	((x) = sysconf(_SC_PAGE_SIZE))
 #endif
 
-#if defined(_WIN32) || defined(MDB_USE_POSIX_SEM)
+#if defined(_WIN32)
 #define MNAME_LEN	32
+#elif defined(MDB_USE_SYSV_SEM)
+#define MNAME_LEN	0
 #else
 #define MNAME_LEN	(sizeof(pthread_mutex_t))
 #endif
@@ -389,7 +354,7 @@ typedef pthread_mutex_t mdb_mutex_t[1], *mdb_mutexref_t;
 #define LOCK_MUTEX(rc, env, mutex) \
 	(((rc) = LOCK_MUTEX0(mutex)) && \
 	 ((rc) = mdb_mutex_failed(env, mutex, rc)))
-static int mdb_mutex_failed(MDB_env *env, mdb_mutexref_t mutex, int rc);
+static int mdb_mutex_failed(MDB_env *env, mdb_mutex_t *mutex, int rc);
 #else
 #define LOCK_MUTEX(rc, env, mutex) ((rc) = LOCK_MUTEX0(mutex))
 #define mdb_mutex_failed(env, mutex, rc) (rc)
@@ -403,13 +368,10 @@ static int mdb_mutex_failed(MDB_env *env, mdb_mutexref_t mutex, int rc);
  *
  *	@note If O_DSYNC is undefined but exists in /usr/include,
  * preferably set some compiler flag to get the definition.
+ * Otherwise compile with the less efficient -DMDB_DSYNC=O_SYNC.
  */
 #ifndef MDB_DSYNC
-# ifdef O_DSYNC
 # define MDB_DSYNC	O_DSYNC
-# else
-# define MDB_DSYNC	O_SYNC
-# endif
 #endif
 #endif
 
@@ -521,19 +483,14 @@ static txnid_t mdb_debug_start;
 	/**	The version number for a database's datafile format. */
 #define MDB_DATA_VERSION	 ((MDB_DEVEL) ? 999 : 1)
 	/**	The version number for a database's lockfile format. */
-#define MDB_LOCK_VERSION	 1
+#define MDB_LOCK_VERSION	 ((MDB_DEVEL) ? 999 : 1)
 
-	/**	@brief The max size of a key we can write, or 0 for computed max.
-	 *
-	 *	This macro should normally be left alone or set to 0.
-	 *	Note that a database with big keys or dupsort data cannot be
-	 *	reliably modified by a liblmdb which uses a smaller max.
-	 *	The default is 511 for backwards compat, or 0 when #MDB_DEVEL.
+	/**	@brief The max size of a key we can write, or 0 for dynamic max.
 	 *
-	 *	Other values are allowed, for backwards compat.  However:
-	 *	A value bigger than the computed max can break if you do not
-	 *	know what you are doing, and liblmdb <= 0.9.10 can break when
-	 *	modifying a DB with keys/dupsort data bigger than its max.
+	 *	Define this as 0 to compute the max from the page size.  511
+	 *	is default for backwards compat: liblmdb <= 0.9.10 can break
+	 *	when modifying a DB with keys/dupsort data bigger than its max.
+	 *	#MDB_DEVEL sets the default to 0.
 	 *
 	 *	Data items in an #MDB_DUPSORT database are also limited to
 	 *	this size, since they're actually keys of a sub-DB.  Keys and
@@ -710,13 +667,15 @@ typedef struct MDB_txbody {
 	uint32_t	mtb_magic;
 		/** Format of this lock file. Must be set to #MDB_LOCK_FORMAT. */
 	uint32_t	mtb_format;
-#if defined(_WIN32) || defined(MDB_USE_POSIX_SEM)
+#if defined(_WIN32)
 	char	mtb_rmname[MNAME_LEN];
+#elif defined(MDB_USE_SYSV_SEM)
+	int 	mtb_semid;
 #else
 		/** Mutex protecting access to this table.
-		 *	This is the reader table lock used with LOCK_MUTEX().
+		 *	This is the #MDB_MUTEX(env,r) reader table lock.
 		 */
-	mdb_mutex_t	mtb_rmutex;
+	pthread_mutex_t	mtb_rmutex;
 #endif
 		/**	The ID of the last transaction committed to the database.
 		 *	This is recorded here only for convenience; the value can always
@@ -742,16 +701,20 @@ typedef struct MDB_txninfo {
 #define mti_numreaders	mt1.mtb.mtb_numreaders
 		char pad[(sizeof(MDB_txbody)+CACHELINE-1) & ~(CACHELINE-1)];
 	} mt1;
+#ifdef MDB_USE_SYSV_SEM
+#define	mti_semid	mt1.mtb.mtb_semid
+#else
 	union {
-#if defined(_WIN32) || defined(MDB_USE_POSIX_SEM)
+#if defined(_WIN32)
 		char mt2_wmname[MNAME_LEN];
 #define	mti_wmname	mt2.mt2_wmname
 #else
-		mdb_mutex_t	mt2_wmutex;
+		pthread_mutex_t	mt2_wmutex;
 #define mti_wmutex	mt2.mt2_wmutex
 #endif
 		char pad[(MNAME_LEN+CACHELINE-1) & ~(CACHELINE-1)];
 	} mt2;
+#endif
 	MDB_reader	mti_readers[1];
 } MDB_txninfo;
 
@@ -760,6 +723,7 @@ typedef struct MDB_txninfo {
 	((uint32_t) \
 	 ((MDB_LOCK_VERSION) \
 	  /* Flags which describe functionality */ \
+	  + (((MNAME_LEN) == 0)   << 18) /* MDB_USE_SYSV_SEM */ \
 	  + (((MDB_PIDLOCK) != 0) << 16)))
 /** @} */
 
@@ -965,7 +929,7 @@ typedef struct MDB_db {
 	pgno_t		md_branch_pages;	/**< number of internal pages */
 	pgno_t		md_leaf_pages;		/**< number of leaf pages */
 	pgno_t		md_overflow_pages;	/**< number of overflow pages */
-	size_t		md_entries;		/**< number of data items */
+	uint64_t		md_entries;		/**< number of data items */
 	pgno_t		md_root;		/**< the root page of this tree */
 } MDB_db;
 
@@ -979,11 +943,6 @@ typedef struct MDB_db {
 #define	FREE_DBI	0
 	/** Handle for the default DB. */
 #define	MAIN_DBI	1
-	/** Number of DBs in metapage (free and main) - also hardcoded elsewhere */
-#define CORE_DBS	2
-
-	/** Number of meta pages - also hardcoded elsewhere */
-#define NUM_METAS	2
 
 	/** Meta page content.
 	 *	A meta page is the start point for accessing a database snapshot.
@@ -996,12 +955,12 @@ typedef struct MDB_meta {
 		/** Version number of this file. Must be set to #MDB_DATA_VERSION. */
 	uint32_t	mm_version;
 	void		*mm_address;		/**< address for fixed mapping */
-	size_t		mm_mapsize;			/**< size of mmap region */
-	MDB_db		mm_dbs[CORE_DBS];	/**< first is free space, 2nd is main db */
+	uint64_t		mm_mapsize;			/**< size of mmap region */
+	MDB_db		mm_dbs[2];			/**< first is free space, 2nd is main db */
 	/** The size of pages used in this DB */
-#define	mm_psize	mm_dbs[FREE_DBI].md_pad
+#define	mm_psize	mm_dbs[0].md_pad
 	/** Any persistent environment flags. @ref mdb_env */
-#define	mm_flags	mm_dbs[FREE_DBI].md_flags
+#define	mm_flags	mm_dbs[0].md_flags
 	pgno_t		mm_last_pg;			/**< last used page in file */
 	volatile txnid_t	mm_txnid;	/**< txnid that committed this page */
 } MDB_meta;
@@ -1036,8 +995,7 @@ typedef struct MDB_dbx {
 	 */
 struct MDB_txn {
 	MDB_txn		*mt_parent;		/**< parent of a nested txn */
-	/** Nested txn under this txn, set together with flag #MDB_TXN_HAS_CHILD */
-	MDB_txn		*mt_child;
+	MDB_txn		*mt_child;		/**< nested txn under this txn */
 	pgno_t		mt_next_pgno;	/**< next unallocated page */
 	/** The ID of this transaction. IDs are integers incrementing from 1.
 	 *	Only committed write transactions increment the ID. If a transaction
@@ -1079,15 +1037,13 @@ struct MDB_txn {
 #define DB_STALE	0x02		/**< Named-DB record is older than txnID */
 #define DB_NEW		0x04		/**< Named-DB handle opened in this txn */
 #define DB_VALID	0x08		/**< DB handle is valid, see also #MDB_VALID */
-#define DB_USRVALID	0x10		/**< As #DB_VALID, but not set for #FREE_DBI */
 /** @} */
 	/** In write txns, array of cursors for each DB */
 	MDB_cursor	**mt_cursors;
 	/** Array of flags for each DB */
 	unsigned char	*mt_dbflags;
-	/**	Number of DB records in use, or 0 when the txn is finished.
-	 *	This number only ever increments until the txn finishes; we
-	 *	don't decrement it when individual DB handles are closed.
+	/**	Number of DB records in use. This number only ever increments;
+	 *	we don't decrement it when individual DB handles are closed.
 	 */
 	MDB_dbi		mt_numdbs;
 
@@ -1095,18 +1051,10 @@ struct MDB_txn {
  *	@ingroup internal
  *	@{
  */
-	/** #mdb_txn_begin() flags */
-#define MDB_TXN_BEGIN_FLAGS	MDB_RDONLY
-#define MDB_TXN_RDONLY		MDB_RDONLY	/**< read-only transaction */
-	/* internal txn flags */
-#define MDB_TXN_WRITEMAP	MDB_WRITEMAP	/**< copy of #MDB_env flag in writers */
-#define MDB_TXN_FINISHED	0x01		/**< txn is finished or never began */
+#define MDB_TXN_RDONLY		0x01		/**< read-only transaction */
 #define MDB_TXN_ERROR		0x02		/**< txn is unusable after an error */
 #define MDB_TXN_DIRTY		0x04		/**< must write, even if dirty list is empty */
 #define MDB_TXN_SPILLS		0x08		/**< txn or a parent has spilled pages */
-#define MDB_TXN_HAS_CHILD	0x10		/**< txn has an #MDB_txn.%mt_child */
-	/** most operations on the txn are currently illegal */
-#define MDB_TXN_BLOCKED		(MDB_TXN_FINISHED|MDB_TXN_ERROR|MDB_TXN_HAS_CHILD)
 /** @} */
 	unsigned int	mt_flags;		/**< @ref mdb_txn */
 	/** #dirty_list room: Array size - \#dirty pages visible to this txn.
@@ -1161,6 +1109,7 @@ struct MDB_cursor {
 #define C_EOF	0x02			/**< No more data */
 #define C_SUB	0x04			/**< Cursor is a sub-cursor */
 #define C_DEL	0x08			/**< last op was a cursor_del */
+#define C_SPLITTING	0x20		/**< Cursor is in page_split */
 #define C_UNTRACK	0x40		/**< Un-track cursor when closing */
 /** @} */
 	unsigned int	mc_flags;	/**< @ref mdb_cursor */
@@ -1207,19 +1156,18 @@ struct MDB_env {
 	unsigned int	me_psize;	/**< DB page size, inited from me_os_psize */
 	unsigned int	me_os_psize;	/**< OS page size, from #GET_PAGESIZE */
 	unsigned int	me_maxreaders;	/**< size of the reader table */
-	/** Max #MDB_txninfo.%mti_numreaders of interest to #mdb_env_close() */
-	volatile int	me_close_readers;
+	unsigned int	me_numreaders;	/**< max numreaders set by this env */
 	MDB_dbi		me_numdbs;		/**< number of DBs opened */
 	MDB_dbi		me_maxdbs;		/**< size of the DB table */
 	MDB_PID_T	me_pid;		/**< process ID of this env */
 	char		*me_path;		/**< path to the DB files */
 	char		*me_map;		/**< the memory map of the data file */
 	MDB_txninfo	*me_txns;		/**< the memory map of the lock file or NULL */
-	MDB_meta	*me_metas[NUM_METAS];	/**< pointers to the two meta pages */
+	MDB_meta	*me_metas[2];	/**< pointers to the two meta pages */
 	void		*me_pbuf;		/**< scratch area for DUPSORT put() */
 	MDB_txn		*me_txn;		/**< current write transaction */
 	MDB_txn		*me_txn0;		/**< prealloc'd write transaction */
-	size_t		me_mapsize;		/**< size of the data memory map */
+	uint64_t		me_mapsize;		/**< size of the data memory map */
 	off_t		me_size;		/**< current file size */
 	pgno_t		me_maxpg;		/**< me_mapsize / me_psize */
 	MDB_dbx		*me_dbxs;		/**< array of static DB info */
@@ -1246,10 +1194,8 @@ struct MDB_env {
 #ifdef _WIN32
 	int		me_pidquery;		/**< Used in OpenProcess */
 #endif
-#ifdef MDB_USE_POSIX_MUTEX	/* Posix mutexes reside in shared mem */
-#	define		me_rmutex	me_txns->mti_rmutex /**< Shared reader lock */
-#	define		me_wmutex	me_txns->mti_wmutex /**< Shared writer lock */
-#else
+#if defined(_WIN32) || defined(MDB_USE_SYSV_SEM)
+	/* Windows mutexes/SysV semaphores do not reside in shared mem */
 	mdb_mutex_t	me_rmutex;
 	mdb_mutex_t	me_wmutex;
 #endif
@@ -1271,11 +1217,11 @@ typedef struct MDB_ntxn {
 #endif
 
 	/** max bytes to write in one call */
-#define MAX_WRITE		(0x40000000U >> (sizeof(ssize_t) == 4))
+#define MAX_WRITE		(0x80000000U >> (sizeof(ssize_t) == 4))
 
 	/** Check \b txn and \b dbi arguments to a function */
-#define TXN_DBI_EXIST(txn, dbi, validity) \
-	((txn) && (dbi)<(txn)->mt_numdbs && ((txn)->mt_dbflags[dbi] & (validity)))
+#define TXN_DBI_EXIST(txn, dbi) \
+	((txn) && (dbi) < (txn)->mt_numdbs && ((txn)->mt_dbflags[dbi] & DB_VALID))
 
 	/** Check for misused \b dbi handles */
 #define TXN_DBI_CHANGED(txn, dbi) \
@@ -1285,19 +1231,6 @@ static int  mdb_page_alloc(MDB_cursor *mc, int num, MDB_page **mp);
 static int  mdb_page_new(MDB_cursor *mc, uint32_t flags, int num, MDB_page **mp);
 static int  mdb_page_touch(MDB_cursor *mc);
 
-#define MDB_END_NAMES {"committed", "empty-commit", "abort", "reset", \
-	"reset-tmp", "fail-begin", "fail-beginchild"}
-enum {
-	/* mdb_txn_end operation number, for logging */
-	MDB_END_COMMITTED, MDB_END_EMPTY_COMMIT, MDB_END_ABORT, MDB_END_RESET,
-	MDB_END_RESET_TMP, MDB_END_FAIL_BEGIN, MDB_END_FAIL_BEGINCHILD
-};
-#define MDB_END_OPMASK	0x0F	/**< mask for #mdb_txn_end() operation number */
-#define MDB_END_UPDATE	0x10	/**< update env state (DBIs) */
-#define MDB_END_FREE	0x20	/**< free txn unless it is #MDB_env.%me_txn0 */
-#define MDB_END_SLOT MDB_NOTLS	/**< release any reader slot if #MDB_NOTLS */
-static void mdb_txn_end(MDB_txn *txn, unsigned mode);
-
 static int  mdb_page_get(MDB_txn *txn, pgno_t pgno, MDB_page **mp, int *lvl);
 static int  mdb_page_search_root(MDB_cursor *mc,
 			    MDB_val *key, int modify);
@@ -1314,9 +1247,9 @@ static int	mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata,
 				pgno_t newpgno, unsigned int nflags);
 
 static int  mdb_env_read_header(MDB_env *env, MDB_meta *meta);
-static MDB_meta *mdb_env_pick_meta(const MDB_env *env);
+static int  mdb_env_pick_meta(const MDB_env *env);
 static int  mdb_env_write_meta(MDB_txn *txn);
-#ifdef MDB_USE_POSIX_MUTEX /* Drop unused excl arg */
+#if !(defined(_WIN32) || defined(MDB_USE_SYSV_SEM)) /* Drop unused excl arg */
 # define mdb_env_close0(env, excl) mdb_env_close1(env)
 #endif
 static void mdb_env_close0(MDB_env *env, int excl);
@@ -1326,7 +1259,7 @@ static int  mdb_node_add(MDB_cursor *mc, indx_t indx,
 			    MDB_val *key, MDB_val *data, pgno_t pgno, unsigned int flags);
 static void mdb_node_del(MDB_cursor *mc, int ksize);
 static void mdb_node_shrink(MDB_page *mp, indx_t indx);
-static int	mdb_node_move(MDB_cursor *csrc, MDB_cursor *cdst, int fromleft);
+static int	mdb_node_move(MDB_cursor *csrc, MDB_cursor *cdst);
 static int  mdb_node_read(MDB_txn *txn, MDB_node *leaf, MDB_val *data);
 static size_t	mdb_leaf_size(MDB_env *env, MDB_val *key, MDB_val *data);
 static size_t	mdb_branch_size(MDB_env *env, MDB_val *key);
@@ -1350,7 +1283,6 @@ static int	mdb_cursor_last(MDB_cursor *mc, MDB_val *key, MDB_val *data);
 static void	mdb_cursor_init(MDB_cursor *mc, MDB_txn *txn, MDB_dbi dbi, MDB_xcursor *mx);
 static void	mdb_xcursor_init0(MDB_cursor *mc);
 static void	mdb_xcursor_init1(MDB_cursor *mc, MDB_node *node);
-static void	mdb_xcursor_init2(MDB_cursor *mc, MDB_xcursor *src_mx, int force);
 
 static int	mdb_drop0(MDB_cursor *mc, int subs);
 static void mdb_default_cmp(MDB_txn *txn, MDB_dbi dbi);
@@ -1360,23 +1292,14 @@ static int mdb_reader_check0(MDB_env *env, int rlocked, int *dead);
 static MDB_cmp_func	mdb_cmp_memn, mdb_cmp_memnr, mdb_cmp_int, mdb_cmp_cint, mdb_cmp_long;
 /** @endcond */
 
-/** Compare two items pointing at size_t's of unknown alignment. */
-#ifdef MISALIGNED_OK
-# define mdb_cmp_clong mdb_cmp_long
-#else
-# define mdb_cmp_clong mdb_cmp_cint
-#endif
-
 #ifdef _WIN32
 static SECURITY_DESCRIPTOR mdb_null_sd;
 static SECURITY_ATTRIBUTES mdb_all_sa;
 static int mdb_sec_inited;
-
-static int utf8_to_utf16(const char *src, int srcsize, wchar_t **dst, int *dstsize);
 #endif
 
 /** Return the library version info. */
-char * ESECT
+char *
 mdb_version(int *major, int *minor, int *patch)
 {
 	if (major) *major = MDB_VERSION_MAJOR;
@@ -1404,7 +1327,7 @@ static char *const mdb_errstr[] = {
 	"MDB_MAP_RESIZED: Database contents grew beyond environment mapsize",
 	"MDB_INCOMPATIBLE: Operation and DB incompatible, or DB flags changed",
 	"MDB_BAD_RSLOT: Invalid reuse of reader locktable slot",
-	"MDB_BAD_TXN: Transaction must abort, has a child, or is invalid",
+	"MDB_BAD_TXN: Transaction cannot recover - it must be aborted",
 	"MDB_BAD_VALSIZE: Unsupported size of key/DB name/data, or wrong DUPFIXED size",
 	"MDB_BAD_DBI: The specified DBI handle was closed/changed unexpectedly",
 };
@@ -1448,7 +1371,7 @@ mdb_strerror(int err)
 		;
 	}
 	buf[0] = 0;
-	FormatMessageA(FORMAT_MESSAGE_FROM_SYSTEM |
+	FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM |
 		FORMAT_MESSAGE_IGNORE_INSERTS,
 		NULL, err, 0, ptr, sizeof(buf), (va_list *)pad);
 	return ptr;
@@ -1460,7 +1383,7 @@ mdb_strerror(int err)
 /** assert(3) variant in cursor context */
 #define mdb_cassert(mc, expr)	mdb_assert0((mc)->mc_txn->mt_env, expr, #expr)
 /** assert(3) variant in transaction context */
-#define mdb_tassert(txn, expr)	mdb_assert0((txn)->mt_env, expr, #expr)
+#define mdb_tassert(mc, expr)	mdb_assert0((txn)->mt_env, expr, #expr)
 /** assert(3) variant in environment context */
 #define mdb_eassert(env, expr)	mdb_assert0(env, expr, #expr)
 
@@ -1468,7 +1391,7 @@ mdb_strerror(int err)
 # define mdb_assert0(env, expr, expr_txt) ((expr) ? (void)0 : \
 		mdb_assert_fail(env, expr_txt, mdb_func_, __FILE__, __LINE__))
 
-static void ESECT
+static void
 mdb_assert_fail(MDB_env *env, const char *expr_txt,
 	const char *func, const char *file, int line)
 {
@@ -1604,7 +1527,7 @@ mdb_cursor_chk(MDB_cursor *mc)
 	MDB_node *node;
 	MDB_page *mp;
 
-	if (!mc->mc_snum || !(mc->mc_flags & C_INITIALIZED)) return;
+	if (!mc->mc_snum && !(mc->mc_flags & C_INITIALIZED)) return;
 	for (i=0; i<mc->mc_top; i++) {
 		mp = mc->mc_pg[i];
 		node = NODEPTR(mp, mc->mc_ki[i]);
@@ -1613,13 +1536,6 @@ mdb_cursor_chk(MDB_cursor *mc)
 	}
 	if (mc->mc_ki[i] >= NUMKEYS(mc->mc_pg[i]))
 		printf("ack!\n");
-	if (mc->mc_xcursor && (mc->mc_xcursor->mx_cursor.mc_flags & C_INITIALIZED)) {
-		node = NODEPTR(mc->mc_pg[mc->mc_top], mc->mc_ki[mc->mc_top]);
-		if (((node->mn_flags & (F_DUPDATA|F_SUBDATA)) == F_DUPDATA) &&
-			mc->mc_xcursor->mx_cursor.mc_pg[0] != NODEDATA(node)) {
-			printf("blah!\n");
-		}
-	}
 }
 #endif
 
@@ -1673,10 +1589,9 @@ static void mdb_audit(MDB_txn *txn)
 			mdb_tassert(txn, rc == MDB_NOTFOUND);
 		}
 	}
-	if (freecount + count + NUM_METAS != txn->mt_next_pgno) {
+	if (freecount + count + 2 /* metapages */ != txn->mt_next_pgno) {
 		fprintf(stderr, "audit: %lu freecount: %lu count: %lu total: %lu next_pgno: %lu\n",
-			txn->mt_txnid, freecount, count+NUM_METAS,
-			freecount+count+NUM_METAS, txn->mt_next_pgno);
+			txn->mt_txnid, freecount, count+2, freecount+count+2, txn->mt_next_pgno);
 	}
 }
 #endif
@@ -1690,12 +1605,7 @@ mdb_cmp(MDB_txn *txn, MDB_dbi dbi, const MDB_val *a, const MDB_val *b)
 int
 mdb_dcmp(MDB_txn *txn, MDB_dbi dbi, const MDB_val *a, const MDB_val *b)
 {
-	MDB_cmp_func *dcmp = txn->mt_dbxs[dbi].md_dcmp;
-#if UINT_MAX < SIZE_MAX
-	if (dcmp == mdb_cmp_int && a->mv_size == sizeof(size_t))
-		dcmp = mdb_cmp_clong;
-#endif
-	return dcmp(a, b);
+	return txn->mt_dbxs[dbi].md_dcmp(a, b);
 }
 
 /** Allocate memory for a page.
@@ -1945,7 +1855,7 @@ mdb_page_spill(MDB_cursor *m0, MDB_val *key, MDB_val *data)
 	/* Estimate how much space this op will take */
 	i = m0->mc_db->md_depth;
 	/* Named DBs also dirty the main DB */
-	if (m0->mc_dbi >= CORE_DBS)
+	if (m0->mc_dbi > MAIN_DBI)
 		i += txn->mt_dbs[MAIN_DBI].md_depth;
 	/* For puts, roughly factor in the key+data size */
 	if (key)
@@ -2054,7 +1964,7 @@ mdb_page_dirty(MDB_txn *txn, MDB_page *mp)
 	MDB_ID2 mid;
 	int rc, (*insert)(MDB_ID2L, MDB_ID2 *);
 
-	if (txn->mt_flags & MDB_TXN_WRITEMAP) {
+	if (txn->mt_env->me_flags & MDB_WRITEMAP) {
 		insert = mdb_mid2l_append;
 	} else {
 		insert = mdb_mid2l_insert;
@@ -2425,15 +2335,14 @@ done:
 	} else {
 		for (; m2; m2=m2->mc_next) {
 			if (m2->mc_snum < mc->mc_snum) continue;
-			if (m2 == mc) continue;
 			if (m2->mc_pg[mc->mc_top] == mp) {
 				m2->mc_pg[mc->mc_top] = np;
 				if ((mc->mc_db->md_flags & MDB_DUPSORT) &&
 					IS_LEAF(np) &&
-					(m2->mc_xcursor->mx_cursor.mc_flags & C_INITIALIZED))
+					m2->mc_ki[mc->mc_top] == mc->mc_ki[mc->mc_top])
 				{
-					MDB_node *leaf = NODEPTR(np, m2->mc_ki[mc->mc_top]);
-					if ((leaf->mn_flags & (F_DUPDATA|F_SUBDATA)) == F_DUPDATA)
+					MDB_node *leaf = NODEPTR(np, mc->mc_ki[mc->mc_top]);
+					if (!(leaf->mn_flags & F_SUBDATA))
 						m2->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
 				}
 			}
@@ -2497,15 +2406,14 @@ mdb_cursor_shadow(MDB_txn *src, MDB_txn *dst)
 				*bk = *mc;
 				mc->mc_backup = bk;
 				mc->mc_db = &dst->mt_dbs[i];
-				/* Kill pointers into src to reduce abuse: The
-				 * user may not use mc until dst ends. But we need a valid
-				 * txn pointer here for cursor fixups to keep working.
+				/* Kill pointers into src - and dst to reduce abuse: The
+				 * user may not use mc until dst ends. Otherwise we'd...
 				 */
-				mc->mc_txn    = dst;
-				mc->mc_dbflag = &dst->mt_dbflags[i];
+				mc->mc_txn    = NULL;	/* ...set this to dst */
+				mc->mc_dbflag = NULL;	/* ...and &dst->mt_dbflags[i] */
 				if ((mx = mc->mc_xcursor) != NULL) {
 					*(MDB_xcursor *)(bk+1) = *mx;
-					mx->mx_cursor.mc_txn = dst;
+					mx->mx_cursor.mc_txn = NULL; /* ...and dst. */
 				}
 				mc->mc_next = dst->mt_cursors[i];
 				dst->mt_cursors[i] = mc;
@@ -2555,6 +2463,12 @@ mdb_cursors_close(MDB_txn *txn, unsigned merge)
 	}
 }
 
+#if !(MDB_DEBUG)
+#define mdb_txn_reset0(txn, act) mdb_txn_reset0(txn)
+#endif
+static void
+mdb_txn_reset0(MDB_txn *txn, const char *act);
+
 #if !(MDB_PIDLOCK)		/* Currently the same as defined(_WIN32) */
 enum Pidlock_op {
 	Pidset, Pidcheck
@@ -2619,13 +2533,16 @@ mdb_txn_renew0(MDB_txn *txn)
 	MDB_env *env = txn->mt_env;
 	MDB_txninfo *ti = env->me_txns;
 	MDB_meta *meta;
-	unsigned int i, nr, flags = txn->mt_flags;
+	unsigned int i, nr;
 	uint16_t x;
 	int rc, new_notls = 0;
 
-	if ((flags &= MDB_TXN_RDONLY) != 0) {
+	if (txn->mt_flags & MDB_TXN_RDONLY) {
+		/* Setup db info */
+		txn->mt_numdbs = env->me_numdbs;
+		txn->mt_dbxs = env->me_dbxs;	/* mostly static anyway */
 		if (!ti) {
-			meta = mdb_env_pick_meta(env);
+			meta = env->me_metas[ mdb_env_pick_meta(env) ];
 			txn->mt_txnid = meta->mm_txnid;
 			txn->mt_u.reader = NULL;
 		} else {
@@ -2637,7 +2554,7 @@ mdb_txn_renew0(MDB_txn *txn)
 			} else {
 				MDB_PID_T pid = env->me_pid;
 				MDB_THR_T tid = pthread_self();
-				mdb_mutexref_t rmutex = env->me_rmutex;
+				mdb_mutex_t *rmutex = MDB_MUTEX(env, r);
 
 				if (!env->me_live_reader) {
 					rc = mdb_reader_pid(env, Pidset, pid);
@@ -2657,19 +2574,13 @@ mdb_txn_renew0(MDB_txn *txn)
 					return MDB_READERS_FULL;
 				}
 				r = &ti->mti_readers[i];
-				/* Claim the reader slot, carefully since other code
-				 * uses the reader table un-mutexed: First reset the
-				 * slot, next publish it in mti_numreaders.  After
-				 * that, it is safe for mdb_env_close() to touch it.
-				 * When it will be closed, we can finally claim it.
-				 */
-				r->mr_pid = 0;
 				r->mr_txnid = (txnid_t)-1;
 				r->mr_tid = tid;
+				r->mr_pid = pid; /* should be written last, see ITS#7971. */
 				if (i == nr)
 					ti->mti_numreaders = ++nr;
-				env->me_close_readers = nr;
-				r->mr_pid = pid;
+				/* Save numreaders for un-mutexed mdb_env_close() */
+				env->me_numreaders = nr;
 				UNLOCK_MUTEX(rmutex);
 
 				new_notls = (env->me_flags & MDB_NOTLS);
@@ -2685,23 +2596,33 @@ mdb_txn_renew0(MDB_txn *txn)
 			txn->mt_u.reader = r;
 			meta = env->me_metas[txn->mt_txnid & 1];
 		}
-
 	} else {
-		/* Not yet touching txn == env->me_txn0, it may be active */
 		if (ti) {
-			if (LOCK_MUTEX(rc, env, env->me_wmutex))
+			if (LOCK_MUTEX(rc, env, MDB_MUTEX(env, w)))
 				return rc;
+#ifdef MDB_USE_SYSV_SEM
+			meta = env->me_metas[ mdb_env_pick_meta(env) ];
+			txn->mt_txnid = meta->mm_txnid;
+			/* Update mti_txnid like mdb_mutex_failed() would,
+			 * in case last writer crashed before updating it.
+			 */
+			ti->mti_txnid = txn->mt_txnid;
+#else
 			txn->mt_txnid = ti->mti_txnid;
 			meta = env->me_metas[txn->mt_txnid & 1];
+#endif
 		} else {
-			meta = mdb_env_pick_meta(env);
+			meta = env->me_metas[ mdb_env_pick_meta(env) ];
 			txn->mt_txnid = meta->mm_txnid;
 		}
+		/* Setup db info */
+		txn->mt_numdbs = env->me_numdbs;
 		txn->mt_txnid++;
 #if MDB_DEBUG
 		if (txn->mt_txnid == mdb_debug_start)
 			mdb_debug = 1;
 #endif
+		txn->mt_flags = 0;
 		txn->mt_child = NULL;
 		txn->mt_loose_pgs = NULL;
 		txn->mt_loose_count = 0;
@@ -2716,33 +2637,28 @@ mdb_txn_renew0(MDB_txn *txn)
 	}
 
 	/* Copy the DB info and flags */
-	memcpy(txn->mt_dbs, meta->mm_dbs, CORE_DBS * sizeof(MDB_db));
+	memcpy(txn->mt_dbs, meta->mm_dbs, 2 * sizeof(MDB_db));
 
 	/* Moved to here to avoid a data race in read TXNs */
 	txn->mt_next_pgno = meta->mm_last_pg+1;
 
-	txn->mt_flags = flags;
-
-	/* Setup db info */
-	txn->mt_numdbs = env->me_numdbs;
-	for (i=CORE_DBS; i<txn->mt_numdbs; i++) {
+	for (i=2; i<txn->mt_numdbs; i++) {
 		x = env->me_dbflags[i];
 		txn->mt_dbs[i].md_flags = x & PERSISTENT_FLAGS;
-		txn->mt_dbflags[i] = (x & MDB_VALID) ? DB_VALID|DB_USRVALID|DB_STALE : 0;
+		txn->mt_dbflags[i] = (x & MDB_VALID) ? DB_VALID|DB_STALE : 0;
 	}
-	txn->mt_dbflags[MAIN_DBI] = DB_VALID|DB_USRVALID;
-	txn->mt_dbflags[FREE_DBI] = DB_VALID;
+	txn->mt_dbflags[0] = txn->mt_dbflags[1] = DB_VALID;
 
-	if (env->me_flags & MDB_FATAL_ERROR) {
-		DPUTS("environment had fatal error, must shutdown!");
-		rc = MDB_PANIC;
-	} else if (env->me_maxpg < txn->mt_next_pgno) {
-		rc = MDB_MAP_RESIZED;
-	} else {
-		return MDB_SUCCESS;
+	if (env->me_maxpg < txn->mt_next_pgno) {
+		mdb_txn_reset0(txn, "renew0-mapfail");
+		if (new_notls) {
+			txn->mt_u.reader->mr_pid = 0;
+			txn->mt_u.reader = NULL;
+		}
+		return MDB_MAP_RESIZED;
 	}
-	mdb_txn_end(txn, new_notls /*0 or MDB_END_SLOT*/ | MDB_END_FAIL_BEGIN);
-	return rc;
+
+	return MDB_SUCCESS;
 }
 
 int
@@ -2750,9 +2666,14 @@ mdb_txn_renew(MDB_txn *txn)
 {
 	int rc;
 
-	if (!txn || !F_ISSET(txn->mt_flags, MDB_TXN_RDONLY|MDB_TXN_FINISHED))
+	if (!txn || txn->mt_dbxs)	/* A reset txn has mt_dbxs==NULL */
 		return EINVAL;
 
+	if (txn->mt_env->me_flags & MDB_FATAL_ERROR) {
+		DPUTS("environment had fatal error, must shutdown!");
+		return MDB_PANIC;
+	}
+
 	rc = mdb_txn_renew0(txn);
 	if (rc == MDB_SUCCESS) {
 		DPRINTF(("renew txn %"Z"u%c %p on mdbenv %p, root page %"Z"u",
@@ -2767,47 +2688,60 @@ mdb_txn_begin(MDB_env *env, MDB_txn *parent, unsigned int flags, MDB_txn **ret)
 {
 	MDB_txn *txn;
 	MDB_ntxn *ntxn;
-	int rc, size, tsize;
-
-	flags &= MDB_TXN_BEGIN_FLAGS;
-	flags |= env->me_flags & MDB_WRITEMAP;
+	int rc, size, tsize = sizeof(MDB_txn);
 
-	if (env->me_flags & MDB_RDONLY & ~flags) /* write txn in RDONLY env */
+	if (env->me_flags & MDB_FATAL_ERROR) {
+		DPUTS("environment had fatal error, must shutdown!");
+		return MDB_PANIC;
+	}
+	if ((env->me_flags & MDB_RDONLY) && !(flags & MDB_RDONLY))
 		return EACCES;
-
 	if (parent) {
 		/* Nested transactions: Max 1 child, write txns only, no writemap */
-		flags |= parent->mt_flags;
-		if (flags & (MDB_RDONLY|MDB_WRITEMAP|MDB_TXN_BLOCKED)) {
+		if (parent->mt_child ||
+			(flags & MDB_RDONLY) ||
+			(parent->mt_flags & (MDB_TXN_RDONLY|MDB_TXN_ERROR)) ||
+			(env->me_flags & MDB_WRITEMAP))
+		{
 			return (parent->mt_flags & MDB_TXN_RDONLY) ? EINVAL : MDB_BAD_TXN;
 		}
-		/* Child txns save MDB_pgstate and use own copy of cursors */
-		size = env->me_maxdbs * (sizeof(MDB_db)+sizeof(MDB_cursor *)+1);
-		size += tsize = sizeof(MDB_ntxn);
-	} else if (flags & MDB_RDONLY) {
-		size = env->me_maxdbs * (sizeof(MDB_db)+1);
-		size += tsize = sizeof(MDB_txn);
-	} else {
-		/* Reuse preallocated write txn. However, do not touch it until
-		 * mdb_txn_renew0() succeeds, since it currently may be active.
-		 */
-		txn = env->me_txn0;
-		goto renew;
+		tsize = sizeof(MDB_ntxn);
+	}
+	size = tsize;
+	if (!(flags & MDB_RDONLY)) {
+		if (!parent) {
+			txn = env->me_txn0;	/* just reuse preallocated write txn */
+			goto ok;
+		}
+		/* child txns use own copy of cursors */
+		size += env->me_maxdbs * sizeof(MDB_cursor *);
 	}
+	size += env->me_maxdbs * (sizeof(MDB_db)+1);
+
 	if ((txn = calloc(1, size)) == NULL) {
 		DPRINTF(("calloc: %s", strerror(errno)));
 		return ENOMEM;
 	}
-	txn->mt_dbxs = env->me_dbxs;	/* static */
 	txn->mt_dbs = (MDB_db *) ((char *)txn + tsize);
-	txn->mt_dbflags = (unsigned char *)txn + size - env->me_maxdbs;
-	txn->mt_flags = flags;
+	if (flags & MDB_RDONLY) {
+		txn->mt_flags |= MDB_TXN_RDONLY;
+		txn->mt_dbflags = (unsigned char *)(txn->mt_dbs + env->me_maxdbs);
+		txn->mt_dbiseqs = env->me_dbiseqs;
+	} else {
+		txn->mt_cursors = (MDB_cursor **)(txn->mt_dbs + env->me_maxdbs);
+		if (parent) {
+			txn->mt_dbiseqs = parent->mt_dbiseqs;
+			txn->mt_dbflags = (unsigned char *)(txn->mt_cursors + env->me_maxdbs);
+		} else {
+			txn->mt_dbiseqs = (unsigned int *)(txn->mt_cursors + env->me_maxdbs);
+			txn->mt_dbflags = (unsigned char *)(txn->mt_dbiseqs + env->me_maxdbs);
+		}
+	}
 	txn->mt_env = env;
 
+ok:
 	if (parent) {
 		unsigned int i;
-		txn->mt_cursors = (MDB_cursor **)(txn->mt_dbs + env->me_maxdbs);
-		txn->mt_dbiseqs = parent->mt_dbiseqs;
 		txn->mt_u.dirty_list = malloc(sizeof(MDB_ID2)*MDB_IDL_UM_SIZE);
 		if (!txn->mt_u.dirty_list ||
 			!(txn->mt_free_pgs = mdb_midl_alloc(MDB_IDL_UM_MAX)))
@@ -2821,10 +2755,11 @@ mdb_txn_begin(MDB_env *env, MDB_txn *parent, unsigned int flags, MDB_txn **ret)
 		txn->mt_u.dirty_list[0].mid = 0;
 		txn->mt_spill_pgs = NULL;
 		txn->mt_next_pgno = parent->mt_next_pgno;
-		parent->mt_flags |= MDB_TXN_HAS_CHILD;
 		parent->mt_child = txn;
 		txn->mt_parent = parent;
 		txn->mt_numdbs = parent->mt_numdbs;
+		txn->mt_flags = parent->mt_flags;
+		txn->mt_dbxs = parent->mt_dbxs;
 		memcpy(txn->mt_dbs, parent->mt_dbs, txn->mt_numdbs * sizeof(MDB_db));
 		/* Copy parent's mt_dbflags, but clear DB_NEW */
 		for (i=0; i<txn->mt_numdbs; i++)
@@ -2843,20 +2778,17 @@ mdb_txn_begin(MDB_env *env, MDB_txn *parent, unsigned int flags, MDB_txn **ret)
 		if (!rc)
 			rc = mdb_cursor_shadow(parent, txn);
 		if (rc)
-			mdb_txn_end(txn, MDB_END_FAIL_BEGINCHILD);
-	} else { /* MDB_RDONLY */
-		txn->mt_dbiseqs = env->me_dbiseqs;
-renew:
+			mdb_txn_reset0(txn, "beginchild-fail");
+	} else {
 		rc = mdb_txn_renew0(txn);
 	}
 	if (rc) {
 		if (txn != env->me_txn0)
 			free(txn);
 	} else {
-		txn->mt_flags |= flags;	/* could not change txn=me_txn0 earlier */
 		*ret = txn;
 		DPRINTF(("begin txn %"Z"u%c %p on mdbenv %p, root page %"Z"u",
-			txn->mt_txnid, (flags & MDB_RDONLY) ? 'r' : 'w',
+			txn->mt_txnid, (txn->mt_flags & MDB_TXN_RDONLY) ? 'r' : 'w',
 			(void *) txn, (void *) env, txn->mt_dbs[MAIN_DBI].md_root));
 	}
 
@@ -2886,7 +2818,7 @@ mdb_dbis_update(MDB_txn *txn, int keep)
 	MDB_env *env = txn->mt_env;
 	unsigned char *tdbflags = txn->mt_dbflags;
 
-	for (i = n; --i >= CORE_DBS;) {
+	for (i = n; --i >= 2;) {
 		if (tdbflags[i] & DB_NEW) {
 			if (keep) {
 				env->me_dbflags[i] = txn->mt_dbs[i].md_flags | MDB_VALID;
@@ -2906,68 +2838,52 @@ mdb_dbis_update(MDB_txn *txn, int keep)
 		env->me_numdbs = n;
 }
 
-/** End a transaction, except successful commit of a nested transaction.
+/** Common code for #mdb_txn_reset() and #mdb_txn_abort().
  * May be called twice for readonly txns: First reset it, then abort.
- * @param[in] txn the transaction handle to end
- * @param[in] mode why and how to end the transaction
+ * @param[in] txn the transaction handle to reset
+ * @param[in] act why the transaction is being reset
  */
 static void
-mdb_txn_end(MDB_txn *txn, unsigned mode)
+mdb_txn_reset0(MDB_txn *txn, const char *act)
 {
 	MDB_env	*env = txn->mt_env;
-#if MDB_DEBUG
-	static const char *const names[] = MDB_END_NAMES;
-#endif
 
-	/* Export or close DBI handles opened in this txn */
-	mdb_dbis_update(txn, mode & MDB_END_UPDATE);
+	/* Close any DBI handles opened in this txn */
+	mdb_dbis_update(txn, 0);
 
 	DPRINTF(("%s txn %"Z"u%c %p on mdbenv %p, root page %"Z"u",
-		names[mode & MDB_END_OPMASK],
-		txn->mt_txnid, (txn->mt_flags & MDB_TXN_RDONLY) ? 'r' : 'w',
+		act, txn->mt_txnid, (txn->mt_flags & MDB_TXN_RDONLY) ? 'r' : 'w',
 		(void *) txn, (void *)env, txn->mt_dbs[MAIN_DBI].md_root));
 
 	if (F_ISSET(txn->mt_flags, MDB_TXN_RDONLY)) {
 		if (txn->mt_u.reader) {
 			txn->mt_u.reader->mr_txnid = (txnid_t)-1;
-			if (!(env->me_flags & MDB_NOTLS)) {
+			if (!(env->me_flags & MDB_NOTLS))
 				txn->mt_u.reader = NULL; /* txn does not own reader */
-			} else if (mode & MDB_END_SLOT) {
-				txn->mt_u.reader->mr_pid = 0;
-				txn->mt_u.reader = NULL;
-			} /* else txn owns the slot until it does MDB_END_SLOT */
 		}
-		txn->mt_numdbs = 0;		/* prevent further DBI activity */
-		txn->mt_flags |= MDB_TXN_FINISHED;
-
-	} else if (!F_ISSET(txn->mt_flags, MDB_TXN_FINISHED)) {
+		txn->mt_numdbs = 0;		/* close nothing if called again */
+		txn->mt_dbxs = NULL;	/* mark txn as reset */
+	} else {
 		pgno_t *pghead = env->me_pghead;
 
-		if (!(mode & MDB_END_UPDATE)) /* !(already closed cursors) */
-			mdb_cursors_close(txn, 0);
+		mdb_cursors_close(txn, 0);
 		if (!(env->me_flags & MDB_WRITEMAP)) {
 			mdb_dlist_free(txn);
 		}
 
-		txn->mt_numdbs = 0;
-		txn->mt_flags = MDB_TXN_FINISHED;
-
 		if (!txn->mt_parent) {
-			mdb_midl_shrink(&txn->mt_free_pgs);
-			env->me_free_pgs = txn->mt_free_pgs;
+			if (mdb_midl_shrink(&txn->mt_free_pgs))
+				env->me_free_pgs = txn->mt_free_pgs;
 			/* me_pgstate: */
 			env->me_pghead = NULL;
 			env->me_pglast = 0;
 
 			env->me_txn = NULL;
-			mode = 0;	/* txn == env->me_txn0, do not free() it */
-
 			/* The writer mutex was locked in mdb_txn_begin. */
 			if (env->me_txns)
-				UNLOCK_MUTEX(env->me_wmutex);
+				UNLOCK_MUTEX(MDB_MUTEX(env, w));
 		} else {
 			txn->mt_parent->mt_child = NULL;
-			txn->mt_parent->mt_flags &= ~MDB_TXN_HAS_CHILD;
 			env->me_pgstate = ((MDB_ntxn *)txn)->mnt_pgstate;
 			mdb_midl_free(txn->mt_free_pgs);
 			mdb_midl_free(txn->mt_spill_pgs);
@@ -2976,9 +2892,6 @@ mdb_txn_end(MDB_txn *txn, unsigned mode)
 
 		mdb_midl_free(pghead);
 	}
-
-	if (mode & MDB_END_FREE)
-		free(txn);
 }
 
 void
@@ -2991,7 +2904,7 @@ mdb_txn_reset(MDB_txn *txn)
 	if (!(txn->mt_flags & MDB_TXN_RDONLY))
 		return;
 
-	mdb_txn_end(txn, MDB_END_RESET);
+	mdb_txn_reset0(txn, "reset");
 }
 
 void
@@ -3003,7 +2916,13 @@ mdb_txn_abort(MDB_txn *txn)
 	if (txn->mt_child)
 		mdb_txn_abort(txn->mt_child);
 
-	mdb_txn_end(txn, MDB_END_ABORT|MDB_END_SLOT|MDB_END_FREE);
+	mdb_txn_reset0(txn, "abort");
+	/* Free reader slot tied to this txn (if MDB_NOTLS && writable FS) */
+	if ((txn->mt_flags & MDB_TXN_RDONLY) && txn->mt_u.reader)
+		txn->mt_u.reader->mr_pid = 0;
+
+	if (txn != txn->mt_env->me_txn0)
+		free(txn);
 }
 
 /** Save the freelist as of this transaction to the freeDB.
@@ -3279,7 +3198,6 @@ mdb_page_flush(MDB_txn *txn, int keep)
 		/* Write up to MDB_COMMIT_PAGES dirty pages at a time. */
 		if (pos!=next_pos || n==MDB_COMMIT_PAGES || wsize+size>MAX_WRITE) {
 			if (n) {
-retry_write:
 				/* Write previous page(s) */
 #ifdef MDB_USE_PWRITEV
 				wres = pwritev(env->me_fd, iov, n, wpos);
@@ -3287,11 +3205,8 @@ retry_write:
 				if (n == 1) {
 					wres = pwrite(env->me_fd, iov[0].iov_base, wsize, wpos);
 				} else {
-retry_seek:
 					if (lseek(env->me_fd, wpos, SEEK_SET) == -1) {
 						rc = ErrCode();
-						if (rc == EINTR)
-							goto retry_seek;
 						DPRINTF(("lseek: %s", strerror(rc)));
 						return rc;
 					}
@@ -3301,8 +3216,6 @@ retry_seek:
 				if (wres != wsize) {
 					if (wres < 0) {
 						rc = ErrCode();
-						if (rc == EINTR)
-							goto retry_write;
 						DPRINTF(("Write error: %s", strerror(rc)));
 					} else {
 						rc = EIO; /* TODO: Use which error code? */
@@ -3354,17 +3267,15 @@ int
 mdb_txn_commit(MDB_txn *txn)
 {
 	int		rc;
-	unsigned int i, end_mode;
+	unsigned int i;
 	MDB_env	*env;
 
-	if (txn == NULL)
+	if (txn == NULL || txn->mt_env == NULL)
 		return EINVAL;
 
-	/* mdb_txn_end() mode for a commit which writes nothing */
-	end_mode = MDB_END_EMPTY_COMMIT|MDB_END_UPDATE|MDB_END_SLOT|MDB_END_FREE;
-
 	if (txn->mt_child) {
 		rc = mdb_txn_commit(txn->mt_child);
+		txn->mt_child = NULL;
 		if (rc)
 			goto fail;
 	}
@@ -3372,11 +3283,14 @@ mdb_txn_commit(MDB_txn *txn)
 	env = txn->mt_env;
 
 	if (F_ISSET(txn->mt_flags, MDB_TXN_RDONLY)) {
-		goto done;
+		mdb_dbis_update(txn, 1);
+		txn->mt_numdbs = 2; /* so txn_abort() doesn't close any new handles */
+		mdb_txn_abort(txn);
+		return MDB_SUCCESS;
 	}
 
-	if (txn->mt_flags & (MDB_TXN_FINISHED|MDB_TXN_ERROR)) {
-		DPUTS("txn has failed/finished, can't commit");
+	if (F_ISSET(txn->mt_flags, MDB_TXN_ERROR)) {
+		DPUTS("error flag is set, can't commit");
 		if (txn->mt_parent)
 			txn->mt_parent->mt_flags |= MDB_TXN_ERROR;
 		rc = MDB_BAD_TXN;
@@ -3408,9 +3322,9 @@ mdb_txn_commit(MDB_txn *txn)
 		/* Update parent's DB table. */
 		memcpy(parent->mt_dbs, txn->mt_dbs, txn->mt_numdbs * sizeof(MDB_db));
 		parent->mt_numdbs = txn->mt_numdbs;
-		parent->mt_dbflags[FREE_DBI] = txn->mt_dbflags[FREE_DBI];
-		parent->mt_dbflags[MAIN_DBI] = txn->mt_dbflags[MAIN_DBI];
-		for (i=CORE_DBS; i<txn->mt_numdbs; i++) {
+		parent->mt_dbflags[0] = txn->mt_dbflags[0];
+		parent->mt_dbflags[1] = txn->mt_dbflags[1];
+		for (i=2; i<txn->mt_numdbs; i++) {
 			/* preserve parent's DB_NEW status */
 			x = parent->mt_dbflags[i] & DB_NEW;
 			parent->mt_dbflags[i] = txn->mt_dbflags[i] | x;
@@ -3439,25 +3353,6 @@ mdb_txn_commit(MDB_txn *txn)
 			pspill[0] = y;
 		}
 
-		/* Remove anything in our spill list from parent's dirty list */
-		if (txn->mt_spill_pgs && txn->mt_spill_pgs[0]) {
-			for (i=1; i<=txn->mt_spill_pgs[0]; i++) {
-				MDB_ID pn = txn->mt_spill_pgs[i];
-				if (pn & 1)
-					continue;	/* deleted spillpg */
-				pn >>= 1;
-				y = mdb_mid2l_search(dst, pn);
-				if (y <= dst[0].mid && dst[y].mid == pn) {
-					free(dst[y].mptr);
-					while (y < dst[0].mid) {
-						dst[y] = dst[y+1];
-						y++;
-					}
-					dst[0].mid--;
-				}
-			}
-		}
-
 		/* Find len = length of merging our dirty list with parent's */
 		x = dst[0].mid;
 		dst[0].mid = 0;		/* simplify loops */
@@ -3503,7 +3398,7 @@ mdb_txn_commit(MDB_txn *txn)
 		}
 
 		/* Append our loose page list to parent's */
-		for (lp = &parent->mt_loose_pgs; *lp; lp = &NEXT_LOOSE_PAGE(*lp))
+		for (lp = &parent->mt_loose_pgs; *lp; lp = &NEXT_LOOSE_PAGE(lp))
 			;
 		*lp = txn->mt_loose_pgs;
 		parent->mt_loose_count += txn->mt_loose_count;
@@ -3530,22 +3425,21 @@ mdb_txn_commit(MDB_txn *txn)
 	    txn->mt_txnid, (void*)txn, (void*)env, txn->mt_dbs[MAIN_DBI].md_root));
 
 	/* Update DB root pointers */
-	if (txn->mt_numdbs > CORE_DBS) {
+	if (txn->mt_numdbs > 2) {
 		MDB_cursor mc;
 		MDB_dbi i;
 		MDB_val data;
 		data.mv_size = sizeof(MDB_db);
 
 		mdb_cursor_init(&mc, txn, MAIN_DBI, NULL);
-		for (i = CORE_DBS; i < txn->mt_numdbs; i++) {
+		for (i = 2; i < txn->mt_numdbs; i++) {
 			if (txn->mt_dbflags[i] & DB_DIRTY) {
 				if (TXN_DBI_CHANGED(txn, i)) {
 					rc = MDB_BAD_DBI;
 					goto fail;
 				}
 				data.mv_data = &txn->mt_dbs[i];
-				rc = mdb_cursor_put(&mc, &txn->mt_dbxs[i].md_name, &data,
-					F_SUBDATA);
+				rc = mdb_cursor_put(&mc, &txn->mt_dbxs[i].md_name, &data, 0);
 				if (rc)
 					goto fail;
 			}
@@ -3558,7 +3452,8 @@ mdb_txn_commit(MDB_txn *txn)
 
 	mdb_midl_free(env->me_pghead);
 	env->me_pghead = NULL;
-	mdb_midl_shrink(&txn->mt_free_pgs);
+	if (mdb_midl_shrink(&txn->mt_free_pgs))
+		env->me_free_pgs = txn->mt_free_pgs;
 
 #if (MDB_DEBUG) > 2
 	mdb_audit(txn);
@@ -3568,10 +3463,21 @@ mdb_txn_commit(MDB_txn *txn)
 		(rc = mdb_env_sync(env, 0)) ||
 		(rc = mdb_env_write_meta(txn)))
 		goto fail;
-	end_mode = MDB_END_COMMITTED|MDB_END_UPDATE;
+
+	/* Free P_LOOSE pages left behind in dirty_list */
+	if (!(env->me_flags & MDB_WRITEMAP))
+		mdb_dlist_free(txn);
 
 done:
-	mdb_txn_end(txn, end_mode);
+	env->me_pglast = 0;
+	env->me_txn = NULL;
+	mdb_dbis_update(txn, 1);
+
+	if (env->me_txns)
+		UNLOCK_MUTEX(MDB_MUTEX(env, w));
+	if (txn != env->me_txn0)
+		free(txn);
+
 	return MDB_SUCCESS;
 
 fail:
@@ -3598,7 +3504,7 @@ mdb_env_read_header(MDB_env *env, MDB_meta *meta)
 	 * Read both meta pages so we can use the latest one.
 	 */
 
-	for (i=off=0; i<NUM_METAS; i++, off += meta->mm_psize) {
+	for (i=off=0; i<2; i++, off = meta->mm_psize) {
 #ifdef _WIN32
 		DWORD len;
 		OVERLAPPED ov;
@@ -3651,11 +3557,11 @@ mdb_env_init_meta0(MDB_env *env, MDB_meta *meta)
 	meta->mm_version = MDB_DATA_VERSION;
 	meta->mm_mapsize = env->me_mapsize;
 	meta->mm_psize = env->me_psize;
-	meta->mm_last_pg = NUM_METAS-1;
+	meta->mm_last_pg = 1;
 	meta->mm_flags = env->me_flags & 0xffff;
-	meta->mm_flags |= MDB_INTEGERKEY; /* this is mm_dbs[FREE_DBI].md_flags */
-	meta->mm_dbs[FREE_DBI].md_root = P_INVALID;
-	meta->mm_dbs[MAIN_DBI].md_root = P_INVALID;
+	meta->mm_flags |= MDB_INTEGERKEY;
+	meta->mm_dbs[0].md_root = P_INVALID;
+	meta->mm_dbs[1].md_root = P_INVALID;
 }
 
 /** Write the environment parameters of a freshly created DB environment.
@@ -3680,18 +3586,14 @@ mdb_env_init_meta(MDB_env *env, MDB_meta *meta)
 	int len;
 #define DO_PWRITE(rc, fd, ptr, size, len, pos)	do { \
 	len = pwrite(fd, ptr, size, pos);	\
-	if (len == -1 && ErrCode() == EINTR) continue; \
-	rc = (len >= 0); break; } while(1)
+	rc = (len >= 0); } while(0)
 #endif
 
 	DPUTS("writing new meta page");
 
 	psize = env->me_psize;
 
-	p = calloc(NUM_METAS, psize);
-	if (!p)
-		return ENOMEM;
-
+	p = calloc(2, psize);
 	p->mp_pgno = 0;
 	p->mp_flags = P_META;
 	*(MDB_meta *)METADATA(p) = *meta;
@@ -3701,10 +3603,10 @@ mdb_env_init_meta(MDB_env *env, MDB_meta *meta)
 	q->mp_flags = P_META;
 	*(MDB_meta *)METADATA(q) = *meta;
 
-	DO_PWRITE(rc, env->me_fd, p, psize * NUM_METAS, len, 0);
+	DO_PWRITE(rc, env->me_fd, p, psize * 2, len, 0);
 	if (!rc)
 		rc = ErrCode();
-	else if ((unsigned) len == psize * NUM_METAS)
+	else if ((unsigned) len == psize * 2)
 		rc = MDB_SUCCESS;
 	else
 		rc = ENOSPC;
@@ -3721,7 +3623,6 @@ mdb_env_write_meta(MDB_txn *txn)
 {
 	MDB_env *env;
 	MDB_meta	meta, metab, *mp;
-	unsigned flags;
 	size_t mapsize;
 	off_t off;
 	int rc, len, toggle;
@@ -3738,33 +3639,34 @@ mdb_env_write_meta(MDB_txn *txn)
 		toggle, txn->mt_dbs[MAIN_DBI].md_root));
 
 	env = txn->mt_env;
-	flags = env->me_flags;
 	mp = env->me_metas[toggle];
 	mapsize = env->me_metas[toggle ^ 1]->mm_mapsize;
 	/* Persist any increases of mapsize config */
 	if (mapsize < env->me_mapsize)
 		mapsize = env->me_mapsize;
 
-	if (flags & MDB_WRITEMAP) {
+	if (env->me_flags & MDB_WRITEMAP) {
 		mp->mm_mapsize = mapsize;
-		mp->mm_dbs[FREE_DBI] = txn->mt_dbs[FREE_DBI];
-		mp->mm_dbs[MAIN_DBI] = txn->mt_dbs[MAIN_DBI];
+		mp->mm_dbs[0] = txn->mt_dbs[0];
+		mp->mm_dbs[1] = txn->mt_dbs[1];
 		mp->mm_last_pg = txn->mt_next_pgno - 1;
-#if (__GNUC__ * 100 + __GNUC_MINOR__ >= 404) && /* TODO: portability */	\
-	!(defined(__i386__) || defined(__x86_64__))
+#if !(defined(_MSC_VER) || defined(__i386__) || defined(__x86_64__))
 		/* LY: issue a memory barrier, if not x86. ITS#7969 */
 		__sync_synchronize();
 #endif
 		mp->mm_txnid = txn->mt_txnid;
-		if (!(flags & (MDB_NOMETASYNC|MDB_NOSYNC))) {
+		if (!(env->me_flags & (MDB_NOMETASYNC|MDB_NOSYNC))) {
 			unsigned meta_size = env->me_psize;
 			rc = (env->me_flags & MDB_MAPASYNC) ? MS_ASYNC : MS_SYNC;
-			ptr = (char *)mp - PAGEHDRSZ;
+			ptr = env->me_map;
+			if (toggle) {
 #ifndef _WIN32	/* POSIX msync() requires ptr = start of OS page */
-			r2 = (ptr - env->me_map) & (env->me_os_psize - 1);
-			ptr -= r2;
-			meta_size += r2;
+				if (meta_size < env->me_os_psize)
+					meta_size += meta_size;
+				else
 #endif
+					ptr += meta_size;
+			}
 			if (MDB_MSYNC(ptr, meta_size, rc)) {
 				rc = ErrCode();
 				goto fail;
@@ -3772,22 +3674,25 @@ mdb_env_write_meta(MDB_txn *txn)
 		}
 		goto done;
 	}
-	metab.mm_txnid = mp->mm_txnid;
-	metab.mm_last_pg = mp->mm_last_pg;
+	metab.mm_txnid = env->me_metas[toggle]->mm_txnid;
+	metab.mm_last_pg = env->me_metas[toggle]->mm_last_pg;
 
 	meta.mm_mapsize = mapsize;
-	meta.mm_dbs[FREE_DBI] = txn->mt_dbs[FREE_DBI];
-	meta.mm_dbs[MAIN_DBI] = txn->mt_dbs[MAIN_DBI];
+	meta.mm_dbs[0] = txn->mt_dbs[0];
+	meta.mm_dbs[1] = txn->mt_dbs[1];
 	meta.mm_last_pg = txn->mt_next_pgno - 1;
 	meta.mm_txnid = txn->mt_txnid;
 
 	off = offsetof(MDB_meta, mm_mapsize);
 	ptr = (char *)&meta + off;
 	len = sizeof(MDB_meta) - off;
-	off += (char *)mp - env->me_map;
+	if (toggle)
+		off += env->me_psize;
+	off += PAGEHDRSZ;
 
 	/* Write to the SYNC fd */
-	mfd = (flags & (MDB_NOSYNC|MDB_NOMETASYNC)) ? env->me_fd : env->me_mfd;
+	mfd = env->me_flags & (MDB_NOSYNC|MDB_NOMETASYNC) ?
+		env->me_fd : env->me_mfd;
 #ifdef _WIN32
 	{
 		memset(&ov, 0, sizeof(ov));
@@ -3796,15 +3701,10 @@ mdb_env_write_meta(MDB_txn *txn)
 			rc = -1;
 	}
 #else
-retry_write:
 	rc = pwrite(mfd, ptr, len, off);
 #endif
 	if (rc != len) {
 		rc = rc < 0 ? ErrCode() : EIO;
-#ifndef _WIN32
-		if (rc == EINTR)
-			goto retry_write;
-#endif
 		DPUTS("write failed, disk error?");
 		/* On a failure, the pagecache still contains the new data.
 		 * Write some old data back, to prevent it from being used.
@@ -3841,13 +3741,12 @@ done:
 
 /** Check both meta pages to see which one is newer.
  * @param[in] env the environment handle
- * @return newest #MDB_meta.
+ * @return meta toggle (0 or 1).
  */
-static MDB_meta *
+static int
 mdb_env_pick_meta(const MDB_env *env)
 {
-	MDB_meta *const *metas = env->me_metas;
-	return metas[ metas[0]->mm_txnid < metas[1]->mm_txnid ];
+	return (env->me_metas[0]->mm_txnid < env->me_metas[1]->mm_txnid);
 }
 
 int ESECT
@@ -3860,13 +3759,13 @@ mdb_env_create(MDB_env **env)
 		return ENOMEM;
 
 	e->me_maxreaders = DEFAULT_READERS;
-	e->me_maxdbs = e->me_numdbs = CORE_DBS;
+	e->me_maxdbs = e->me_numdbs = 2;
 	e->me_fd = INVALID_HANDLE_VALUE;
 	e->me_lfd = INVALID_HANDLE_VALUE;
 	e->me_mfd = INVALID_HANDLE_VALUE;
-#ifdef MDB_USE_POSIX_SEM
-	e->me_rmutex = SEM_FAILED;
-	e->me_wmutex = SEM_FAILED;
+#ifdef MDB_USE_SYSV_SEM
+	e->me_rmutex.semid = -1;
+	e->me_wmutex.semid = -1;
 #endif
 	e->me_pid = getpid();
 	GET_PAGESIZE(e->me_os_psize);
@@ -3971,7 +3870,7 @@ mdb_env_set_mapsize(MDB_env *env, size_t size)
 		void *old;
 		if (env->me_txn)
 			return EINVAL;
-		meta = mdb_env_pick_meta(env);
+		meta = env->me_metas[mdb_env_pick_meta(env)];
 		if (!size)
 			size = meta->mm_mapsize;
 		{
@@ -3998,7 +3897,7 @@ mdb_env_set_maxdbs(MDB_env *env, MDB_dbi dbs)
 {
 	if (env->me_map)
 		return EINVAL;
-	env->me_maxdbs = dbs + CORE_DBS;
+	env->me_maxdbs = dbs + 2; /* Named databases + main and free DB */
 	return MDB_SUCCESS;
 }
 
@@ -4178,12 +4077,12 @@ mdb_env_open2(MDB_env *env)
 
 #if MDB_DEBUG
 	{
-		MDB_meta *meta = mdb_env_pick_meta(env);
-		MDB_db *db = &meta->mm_dbs[MAIN_DBI];
+		int toggle = mdb_env_pick_meta(env);
+		MDB_db *db = &env->me_metas[toggle]->mm_dbs[MAIN_DBI];
 
 		DPRINTF(("opened database version %u, pagesize %u",
-			meta->mm_version, env->me_psize));
-		DPRINTF(("using meta page %d",    (int) (meta->mm_txnid & 1)));
+			env->me_metas[0]->mm_version, env->me_psize));
+		DPRINTF(("using meta page %d",    toggle));
 		DPRINTF(("depth: %u",             db->md_depth));
 		DPRINTF(("entries: %"Z"u",        db->md_entries));
 		DPRINTF(("branch pages: %"Z"u",   db->md_branch_pages));
@@ -4270,10 +4169,9 @@ PIMAGE_TLS_CALLBACK mdb_tls_cbp = mdb_tls_callback;
 static int ESECT
 mdb_env_share_locks(MDB_env *env, int *excl)
 {
-	int rc = 0;
-	MDB_meta *meta = mdb_env_pick_meta(env);
+	int rc = 0, toggle = mdb_env_pick_meta(env);
 
-	env->me_txns->mti_txnid = meta->mm_txnid;
+	env->me_txns->mti_txnid = env->me_metas[toggle]->mm_txnid;
 
 #ifdef _WIN32
 	{
@@ -4338,8 +4236,8 @@ mdb_env_excl_lock(MDB_env *env, int *excl)
 	if (!rc) {
 		*excl = 1;
 	} else
-# ifndef MDB_USE_POSIX_MUTEX
-	if (*excl < 0) /* always true when MDB_USE_POSIX_MUTEX */
+# ifdef MDB_USE_SYSV_SEM
+	if (*excl < 0) /* always true when !MDB_USE_SYSV_SEM */
 # endif
 	{
 		lock_info.l_type = F_RDLCK;
@@ -4422,7 +4320,7 @@ mdb_hash_val(MDB_val *val, mdb_hash_t hval)
  */
 static const char mdb_a85[]= "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~";
 
-static void ESECT
+static void
 mdb_pack85(unsigned long l, char *out)
 {
 	int i;
@@ -4433,7 +4331,7 @@ mdb_pack85(unsigned long l, char *out)
 	}
 }
 
-static void ESECT
+static void
 mdb_hash_enc(MDB_val *val, char *encbuf)
 {
 	mdb_hash_t h = mdb_hash_val(val, MDB_HASH_INIT);
@@ -4469,14 +4367,9 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
 	off_t size, rsize;
 
 #ifdef _WIN32
-	wchar_t *wlpath;
-	rc = utf8_to_utf16(lpath, -1, &wlpath, NULL);
-	if (rc)
-		return rc;
-	env->me_lfd = CreateFileW(wlpath, GENERIC_READ|GENERIC_WRITE,
-		FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS,
+	env->me_lfd = CreateFileA(lpath, GENERIC_READ|GENERIC_WRITE,
+		FILE_SHARE_READ, NULL, OPEN_ALWAYS,
 		FILE_ATTRIBUTE_NORMAL, NULL);
-	free(wlpath);
 #else
 	env->me_lfd = open(lpath, O_RDWR|O_CREAT|MDB_CLOEXEC, mode);
 #endif
@@ -4578,45 +4471,27 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
 		mdb_hash_enc(&val, encbuf);
 		sprintf(env->me_txns->mti_rmname, "Global\\MDBr%s", encbuf);
 		sprintf(env->me_txns->mti_wmname, "Global\\MDBw%s", encbuf);
-		env->me_rmutex = CreateMutexA(&mdb_all_sa, FALSE, env->me_txns->mti_rmname);
+		env->me_rmutex = CreateMutex(&mdb_all_sa, FALSE, env->me_txns->mti_rmname);
 		if (!env->me_rmutex) goto fail_errno;
-		env->me_wmutex = CreateMutexA(&mdb_all_sa, FALSE, env->me_txns->mti_wmname);
+		env->me_wmutex = CreateMutex(&mdb_all_sa, FALSE, env->me_txns->mti_wmname);
 		if (!env->me_wmutex) goto fail_errno;
-#elif defined(MDB_USE_POSIX_SEM)
-		struct stat stbuf;
-		struct {
-			dev_t dev;
-			ino_t ino;
-		} idbuf;
-		MDB_val val;
-		char encbuf[11];
+#elif defined(MDB_USE_SYSV_SEM)
+		union semun semu;
+		unsigned short vals[2] = {1, 1};
+		int semid = semget(IPC_PRIVATE, 2, mode);
+		if (semid < 0)
+			goto fail_errno;
 
-#if defined(__NetBSD__)
-#define	MDB_SHORT_SEMNAMES	1	/* limited to 14 chars */
-#endif
-		if (fstat(env->me_lfd, &stbuf)) goto fail_errno;
-		idbuf.dev = stbuf.st_dev;
-		idbuf.ino = stbuf.st_ino;
-		val.mv_data = &idbuf;
-		val.mv_size = sizeof(idbuf);
-		mdb_hash_enc(&val, encbuf);
-#ifdef MDB_SHORT_SEMNAMES
-		encbuf[9] = '\0';	/* drop name from 15 chars to 14 chars */
-#endif
-		sprintf(env->me_txns->mti_rmname, "/MDBr%s", encbuf);
-		sprintf(env->me_txns->mti_wmname, "/MDBw%s", encbuf);
-		/* Clean up after a previous run, if needed:  Try to
-		 * remove both semaphores before doing anything else.
-		 */
-		sem_unlink(env->me_txns->mti_rmname);
-		sem_unlink(env->me_txns->mti_wmname);
-		env->me_rmutex = sem_open(env->me_txns->mti_rmname,
-			O_CREAT|O_EXCL, mode, 1);
-		if (env->me_rmutex == SEM_FAILED) goto fail_errno;
-		env->me_wmutex = sem_open(env->me_txns->mti_wmname,
-			O_CREAT|O_EXCL, mode, 1);
-		if (env->me_wmutex == SEM_FAILED) goto fail_errno;
-#else	/* MDB_USE_POSIX_MUTEX: */
+		env->me_rmutex.semid = semid;
+		env->me_wmutex.semid = semid;
+		env->me_rmutex.semnum = 0;
+		env->me_wmutex.semnum = 1;
+
+		semu.array = vals;
+		if (semctl(semid, 0, SETALL, semu) < 0)
+			goto fail_errno;
+		env->me_txns->mti_semid = semid;
+#else	/* MDB_USE_SYSV_SEM */
 		pthread_mutexattr_t mattr;
 
 		if ((rc = pthread_mutexattr_init(&mattr))
@@ -4624,11 +4499,11 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
 #ifdef MDB_ROBUST_SUPPORTED
 			|| (rc = pthread_mutexattr_setrobust(&mattr, PTHREAD_MUTEX_ROBUST))
 #endif
-			|| (rc = pthread_mutex_init(env->me_txns->mti_rmutex, &mattr))
-			|| (rc = pthread_mutex_init(env->me_txns->mti_wmutex, &mattr)))
+			|| (rc = pthread_mutex_init(&env->me_txns->mti_rmutex, &mattr))
+			|| (rc = pthread_mutex_init(&env->me_txns->mti_wmutex, &mattr)))
 			goto fail;
 		pthread_mutexattr_destroy(&mattr);
-#endif	/* _WIN32 || MDB_USE_POSIX_SEM */
+#endif	/* _WIN32 || MDB_USE_SYSV_SEM */
 
 		env->me_txns->mti_magic = MDB_MAGIC;
 		env->me_txns->mti_format = MDB_LOCK_FORMAT;
@@ -4636,6 +4511,11 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
 		env->me_txns->mti_numreaders = 0;
 
 	} else {
+#ifdef MDB_USE_SYSV_SEM
+		struct semid_ds buf;
+		union semun semu;
+		int semid;
+#endif
 		if (env->me_txns->mti_magic != MDB_MAGIC) {
 			DPUTS("lock region has invalid magic");
 			rc = MDB_INVALID;
@@ -4652,15 +4532,25 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
 			goto fail;
 		}
 #ifdef _WIN32
-		env->me_rmutex = OpenMutexA(SYNCHRONIZE, FALSE, env->me_txns->mti_rmname);
+		env->me_rmutex = OpenMutex(SYNCHRONIZE, FALSE, env->me_txns->mti_rmname);
 		if (!env->me_rmutex) goto fail_errno;
-		env->me_wmutex = OpenMutexA(SYNCHRONIZE, FALSE, env->me_txns->mti_wmname);
+		env->me_wmutex = OpenMutex(SYNCHRONIZE, FALSE, env->me_txns->mti_wmname);
 		if (!env->me_wmutex) goto fail_errno;
-#elif defined(MDB_USE_POSIX_SEM)
-		env->me_rmutex = sem_open(env->me_txns->mti_rmname, 0);
-		if (env->me_rmutex == SEM_FAILED) goto fail_errno;
-		env->me_wmutex = sem_open(env->me_txns->mti_wmname, 0);
-		if (env->me_wmutex == SEM_FAILED) goto fail_errno;
+#elif defined(MDB_USE_SYSV_SEM)
+		semid = env->me_txns->mti_semid;
+		semu.buf = &buf;
+
+		/* check for read access */
+		if (semctl(semid, 0, IPC_STAT, semu) < 0)
+			goto fail_errno;
+		/* check for write access */
+		if (semctl(semid, 0, IPC_SET, semu) < 0)
+			goto fail_errno;
+
+		env->me_rmutex.semid = semid;
+		env->me_wmutex.semid = semid;
+		env->me_rmutex.semnum = 0;
+		env->me_wmutex.semnum = 1;
 #endif
 	}
 	return MDB_SUCCESS;
@@ -4694,9 +4584,6 @@ mdb_env_open(MDB_env *env, const char *path, unsigned int flags, mdb_mode_t mode
 {
 	int		oflags, rc, len, excl = -1;
 	char *lpath, *dpath;
-#ifdef _WIN32
-	wchar_t *wpath;
-#endif
 
 	if (env->me_fd!=INVALID_HANDLE_VALUE || (flags & ~(CHANGEABLE|CHANGELESS)))
 		return EINVAL;
@@ -4742,7 +4629,6 @@ mdb_env_open(MDB_env *env, const char *path, unsigned int flags, mdb_mode_t mode
 		rc = ENOMEM;
 		goto leave;
 	}
-	env->me_dbxs[FREE_DBI].md_cmp = mdb_cmp_long; /* aligned MDB_INTEGERKEY */
 
 	/* For RDONLY, get lockfile after we know datafile exists */
 	if (!(flags & (MDB_RDONLY|MDB_NOLOCK))) {
@@ -4760,12 +4646,7 @@ mdb_env_open(MDB_env *env, const char *path, unsigned int flags, mdb_mode_t mode
 		len = OPEN_ALWAYS;
 	}
 	mode = FILE_ATTRIBUTE_NORMAL;
-	rc = utf8_to_utf16(dpath, -1, &wpath, NULL);
-	if (rc)
-		goto leave;
-	env->me_fd = CreateFileW(wpath, oflags, FILE_SHARE_READ|FILE_SHARE_WRITE,
-		NULL, len, mode, NULL);
-	free(wpath);
+	env->me_fd = CreateFileA(dpath, oflags, FILE_SHARE_READ, NULL, len, mode, NULL);
 #else
 	if (F_ISSET(flags, MDB_RDONLY))
 		oflags = O_RDONLY;
@@ -4794,13 +4675,7 @@ mdb_env_open(MDB_env *env, const char *path, unsigned int flags, mdb_mode_t mode
 			 */
 #ifdef _WIN32
 			len = OPEN_EXISTING;
-			rc = utf8_to_utf16(dpath, -1, &wpath, NULL);
-			if (rc)
-				goto leave;
-			env->me_mfd = CreateFileW(wpath, oflags,
-				FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, len,
-				mode | FILE_FLAG_WRITE_THROUGH, NULL);
-			free(wpath);
+			env->me_mfd = CreateFileA(dpath, oflags, FILE_SHARE_READ, NULL, len, mode | FILE_FLAG_WRITE_THROUGH, NULL);
 #else
 			oflags &= ~O_CREAT;
 			env->me_mfd = open(dpath, oflags | MDB_DSYNC, mode);
@@ -4816,20 +4691,21 @@ mdb_env_open(MDB_env *env, const char *path, unsigned int flags, mdb_mode_t mode
 			if (rc)
 				goto leave;
 		}
+		if (!((flags & MDB_RDONLY) ||
+			  (env->me_pbuf = calloc(1, env->me_psize))))
+			rc = ENOMEM;
 		if (!(flags & MDB_RDONLY)) {
 			MDB_txn *txn;
 			int tsize = sizeof(MDB_txn), size = tsize + env->me_maxdbs *
 				(sizeof(MDB_db)+sizeof(MDB_cursor *)+sizeof(unsigned int)+1);
-			if ((env->me_pbuf = calloc(1, env->me_psize)) &&
-				(txn = calloc(1, size)))
-			{
+			txn = calloc(1, size);
+			if (txn) {
 				txn->mt_dbs = (MDB_db *)((char *)txn + tsize);
 				txn->mt_cursors = (MDB_cursor **)(txn->mt_dbs + env->me_maxdbs);
 				txn->mt_dbiseqs = (unsigned int *)(txn->mt_cursors + env->me_maxdbs);
 				txn->mt_dbflags = (unsigned char *)(txn->mt_dbiseqs + env->me_maxdbs);
 				txn->mt_env = env;
 				txn->mt_dbxs = env->me_dbxs;
-				txn->mt_flags = MDB_TXN_FINISHED;
 				env->me_txn0 = txn;
 			} else {
 				rc = ENOMEM;
@@ -4855,15 +4731,13 @@ mdb_env_close0(MDB_env *env, int excl)
 		return;
 
 	/* Doing this here since me_dbxs may not exist during mdb_env_close */
-	if (env->me_dbxs) {
-		for (i = env->me_maxdbs; --i >= CORE_DBS; )
-			free(env->me_dbxs[i].md_name.mv_data);
-		free(env->me_dbxs);
-	}
+	for (i = env->me_maxdbs; --i > MAIN_DBI; )
+		free(env->me_dbxs[i].md_name.mv_data);
 
 	free(env->me_pbuf);
 	free(env->me_dbiseqs);
 	free(env->me_dbflags);
+	free(env->me_dbxs);
 	free(env->me_path);
 	free(env->me_dirty_list);
 	free(env->me_txn0);
@@ -4893,12 +4767,8 @@ mdb_env_close0(MDB_env *env, int excl)
 		MDB_PID_T pid = env->me_pid;
 		/* Clearing readers is done in this function because
 		 * me_txkey with its destructor must be disabled first.
-		 *
-		 * We skip the the reader mutex, so we touch only
-		 * data owned by this process (me_close_readers and
-		 * our readers), and clear each reader atomically.
 		 */
-		for (i = env->me_close_readers; --i >= 0; )
+		for (i = env->me_numreaders; --i >= 0; )
 			if (env->me_txns->mti_readers[i].mr_pid == pid)
 				env->me_txns->mti_readers[i].mr_pid = 0;
 #ifdef _WIN32
@@ -4909,20 +4779,15 @@ mdb_env_close0(MDB_env *env, int excl)
 		/* Windows automatically destroys the mutexes when
 		 * the last handle closes.
 		 */
-#elif defined(MDB_USE_POSIX_SEM)
-		if (env->me_rmutex != SEM_FAILED) {
-			sem_close(env->me_rmutex);
-			if (env->me_wmutex != SEM_FAILED)
-				sem_close(env->me_wmutex);
+#elif defined(MDB_USE_SYSV_SEM)
+		if (env->me_rmutex.semid != -1) {
 			/* If we have the filelock:  If we are the
 			 * only remaining user, clean up semaphores.
 			 */
 			if (excl == 0)
 				mdb_env_excl_lock(env, &excl);
-			if (excl > 0) {
-				sem_unlink(env->me_txns->mti_rmname);
-				sem_unlink(env->me_txns->mti_wmname);
-			}
+			if (excl > 0)
+				semctl(env->me_rmutex.semid, 0, IPC_RMID);
 		}
 #endif
 		munmap((void *)env->me_txns, (env->me_maxreaders-1)*sizeof(MDB_reader)+sizeof(MDB_txninfo));
@@ -4969,11 +4834,7 @@ mdb_cmp_long(const MDB_val *a, const MDB_val *b)
 		*(size_t *)a->mv_data > *(size_t *)b->mv_data;
 }
 
-/** Compare two items pointing at aligned unsigned int's.
- *
- *	This is also set as #MDB_INTEGERDUP|#MDB_DUPFIXED's #MDB_dbx.%md_dcmp,
- *	but #mdb_cmp_clong() is called instead if the data type is size_t.
- */
+/** Compare two items pointing at aligned unsigned int's */
 static int
 mdb_cmp_int(const MDB_val *a, const MDB_val *b)
 {
@@ -5011,6 +4872,13 @@ mdb_cmp_cint(const MDB_val *a, const MDB_val *b)
 #endif
 }
 
+/** Compare two items pointing at size_t's of unknown alignment. */
+#ifdef MISALIGNED_OK
+# define mdb_cmp_clong mdb_cmp_long
+#else
+# define mdb_cmp_clong mdb_cmp_cint
+#endif
+
 /** Compare two items lexically */
 static int
 mdb_cmp_memn(const MDB_val *a, const MDB_val *b)
@@ -5091,7 +4959,7 @@ mdb_node_search(MDB_cursor *mc, MDB_val *key, int *exactp)
 	if (cmp == mdb_cmp_cint && IS_BRANCH(mp)) {
 		if (NODEPTR(mp, 1)->mn_ksize == sizeof(size_t))
 			cmp = mdb_cmp_long;
-		else
+		else if(NODEPTR(mp, 1)->mn_ksize == sizeof(int))
 			cmp = mdb_cmp_int;
 	}
 
@@ -5173,15 +5041,15 @@ static void
 mdb_cursor_pop(MDB_cursor *mc)
 {
 	if (mc->mc_snum) {
-		DPRINTF(("popping page %"Z"u off db %d cursor %p",
-			mc->mc_pg[mc->mc_top]->mp_pgno, DDBI(mc), (void *) mc));
-
+#if MDB_DEBUG
+		MDB_page	*top = mc->mc_pg[mc->mc_top];
+#endif
 		mc->mc_snum--;
-		if (mc->mc_snum) {
+		if (mc->mc_snum)
 			mc->mc_top--;
-		} else {
-			mc->mc_flags &= ~C_INITIALIZED;
-		}
+
+		DPRINTF(("popped page %"Z"u off db %d cursor %p", top->mp_pgno,
+			DDBI(mc), (void *) mc));
 	}
 }
 
@@ -5218,7 +5086,7 @@ mdb_page_get(MDB_txn *txn, pgno_t pgno, MDB_page **ret, int *lvl)
 	MDB_page *p = NULL;
 	int level;
 
-	if (! (txn->mt_flags & (MDB_TXN_RDONLY|MDB_TXN_WRITEMAP))) {
+	if (!((txn->mt_flags & MDB_TXN_RDONLY) | (env->me_flags & MDB_WRITEMAP))) {
 		MDB_txn *tx2 = txn;
 		level = 1;
 		do {
@@ -5279,11 +5147,7 @@ mdb_page_search_root(MDB_cursor *mc, MDB_val *key, int flags)
 		indx_t		i;
 
 		DPRINTF(("branch page %"Z"u has %u keys", mp->mp_pgno, NUMKEYS(mp)));
-		/* Don't assert on branch pages in the FreeDB. We can get here
-		 * while in the process of rebalancing a FreeDB branch page; we must
-		 * let that proceed. ITS#8336
-		 */
-		mdb_cassert(mc, !mc->mc_dbi || NUMKEYS(mp) > 1);
+		mdb_cassert(mc, NUMKEYS(mp) > 1);
 		DPRINTF(("found index 0 to page %"Z"u", NODEPGNO(NODEPTR(mp, 0))));
 
 		if (flags & (MDB_PS_FIRST|MDB_PS_LAST)) {
@@ -5379,8 +5243,8 @@ mdb_page_search(MDB_cursor *mc, MDB_val *key, int flags)
 	/* Make sure the txn is still viable, then find the root from
 	 * the txn's db table and set it as the root of the cursor's stack.
 	 */
-	if (mc->mc_txn->mt_flags & MDB_TXN_BLOCKED) {
-		DPUTS("transaction may not be used now");
+	if (F_ISSET(mc->mc_txn->mt_flags, MDB_TXN_ERROR)) {
+		DPUTS("transaction has failed, must abort");
 		return MDB_BAD_TXN;
 	} else {
 		/* Make sure we're using an up-to-date root */
@@ -5400,8 +5264,6 @@ mdb_page_search(MDB_cursor *mc, MDB_val *key, int flags)
 						&mc->mc_dbx->md_name, &exact);
 					if (!exact)
 						return MDB_NOTFOUND;
-					if ((leaf->mn_flags & (F_DUPDATA|F_SUBDATA)) != F_SUBDATA)
-						return MDB_INCOMPATIBLE; /* not a named DB */
 					rc = mdb_node_read(mc->mc_txn, leaf, &data);
 					if (rc)
 						return rc;
@@ -5501,7 +5363,6 @@ mdb_ovpage_free(MDB_cursor *mc, MDB_page *mp)
 				return MDB_CORRUPTED;
 			}
 		}
-		txn->mt_dirty_room++;
 		if (!(env->me_flags & MDB_WRITEMAP))
 			mdb_dpage_free(env, mp);
 release:
@@ -5565,10 +5426,10 @@ mdb_get(MDB_txn *txn, MDB_dbi dbi,
 
 	DPRINTF(("===> get db %u key [%s]", dbi, DKEY(key)));
 
-	if (!key || !data || !TXN_DBI_EXIST(txn, dbi, DB_USRVALID))
+	if (!key || !data || dbi == FREE_DBI || !TXN_DBI_EXIST(txn, dbi))
 		return EINVAL;
 
-	if (txn->mt_flags & MDB_TXN_BLOCKED)
+	if (txn->mt_flags & MDB_TXN_ERROR)
 		return MDB_BAD_TXN;
 
 	mdb_cursor_init(&mc, txn, dbi, &mx);
@@ -5668,10 +5529,8 @@ mdb_cursor_next(MDB_cursor *mc, MDB_val *key, MDB_val *data, MDB_cursor_op op)
 
 	DPRINTF(("cursor_next: top page is %"Z"u in cursor %p",
 		mdb_dbg_pgno(mp), (void *) mc));
-	if (mc->mc_flags & C_DEL) {
-		mc->mc_flags ^= C_DEL;
+	if (mc->mc_flags & C_DEL)
 		goto skip;
-	}
 
 	if (mc->mc_ki[mc->mc_top] + 1u >= NUMKEYS(mp)) {
 		DPUTS("=====> move to next sibling page");
@@ -5750,8 +5609,6 @@ mdb_cursor_prev(MDB_cursor *mc, MDB_val *key, MDB_val *data, MDB_cursor_op op)
 	DPRINTF(("cursor_prev: top page is %"Z"u in cursor %p",
 		mdb_dbg_pgno(mp), (void *) mc));
 
-	mc->mc_flags &= ~(C_EOF|C_DEL);
-
 	if (mc->mc_ki[mc->mc_top] == 0)  {
 		DPUTS("=====> move to prev sibling page");
 		if ((rc = mdb_cursor_sibling(mc, 0)) != MDB_SUCCESS) {
@@ -5763,6 +5620,8 @@ mdb_cursor_prev(MDB_cursor *mc, MDB_val *key, MDB_val *data, MDB_cursor_op op)
 	} else
 		mc->mc_ki[mc->mc_top]--;
 
+	mc->mc_flags &= ~C_EOF;
+
 	DPRINTF(("==> cursor points to page %"Z"u with %u keys, key index %u",
 	    mdb_dbg_pgno(mp), NUMKEYS(mp), mc->mc_ki[mc->mc_top]));
 
@@ -5898,8 +5757,6 @@ mdb_cursor_set(MDB_cursor *mc, MDB_val *key, MDB_val *data,
 			} else
 				return MDB_NOTFOUND;
 		}
-	} else {
-		mc->mc_pg[0] = 0;
 	}
 
 	rc = mdb_page_search(mc, key, 0);
@@ -5918,10 +5775,8 @@ set2:
 
 	if (leaf == NULL) {
 		DPUTS("===> inexact leaf not found, goto sibling");
-		if ((rc = mdb_cursor_sibling(mc, 1)) != MDB_SUCCESS) {
-			mc->mc_flags |= C_EOF;
+		if ((rc = mdb_cursor_sibling(mc, 1)) != MDB_SUCCESS)
 			return rc;		/* no entries matched */
-		}
 		mp = mc->mc_pg[mc->mc_top];
 		mdb_cassert(mc, IS_LEAF(mp));
 		leaf = NODEPTR(mp, 0);
@@ -5959,21 +5814,15 @@ set1:
 					return rc;
 			}
 		} else if (op == MDB_GET_BOTH || op == MDB_GET_BOTH_RANGE) {
-			MDB_val olddata;
-			MDB_cmp_func *dcmp;
-			if ((rc = mdb_node_read(mc->mc_txn, leaf, &olddata)) != MDB_SUCCESS)
+			MDB_val d2;
+			if ((rc = mdb_node_read(mc->mc_txn, leaf, &d2)) != MDB_SUCCESS)
 				return rc;
-			dcmp = mc->mc_dbx->md_dcmp;
-#if UINT_MAX < SIZE_MAX
-			if (dcmp == mdb_cmp_int && olddata.mv_size == sizeof(size_t))
-				dcmp = mdb_cmp_clong;
-#endif
-			rc = dcmp(data, &olddata);
+			rc = mc->mc_dbx->md_dcmp(data, &d2);
 			if (rc) {
 				if (op == MDB_GET_BOTH || rc > 0)
 					return MDB_NOTFOUND;
 				rc = 0;
-				*data = olddata;
+				*data = d2;
 			}
 
 		} else {
@@ -6093,7 +5942,7 @@ mdb_cursor_get(MDB_cursor *mc, MDB_val *key, MDB_val *data,
 	if (mc == NULL)
 		return EINVAL;
 
-	if (mc->mc_txn->mt_flags & MDB_TXN_BLOCKED)
+	if (mc->mc_txn->mt_flags & MDB_TXN_ERROR)
 		return MDB_BAD_TXN;
 
 	switch (op) {
@@ -6117,6 +5966,8 @@ mdb_cursor_get(MDB_cursor *mc, MDB_val *key, MDB_val *data,
 				MDB_GET_KEY(leaf, key);
 				if (data) {
 					if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+						if (mc->mc_flags & C_DEL)
+							mdb_xcursor_init1(mc, leaf);
 						rc = mdb_cursor_get(&mc->mc_xcursor->mx_cursor, data, NULL, MDB_GET_CURRENT);
 					} else {
 						rc = mdb_node_read(mc->mc_txn, leaf, data);
@@ -6262,7 +6113,7 @@ mdb_cursor_touch(MDB_cursor *mc)
 {
 	int rc = MDB_SUCCESS;
 
-	if (mc->mc_dbi >= CORE_DBS && !(*mc->mc_dbflag & DB_DIRTY)) {
+	if (mc->mc_dbi > MAIN_DBI && !(*mc->mc_dbflag & DB_DIRTY)) {
 		MDB_cursor mc2;
 		MDB_xcursor mcx;
 		if (TXN_DBI_CHANGED(mc->mc_txn, mc->mc_dbi))
@@ -6290,9 +6141,10 @@ int
 mdb_cursor_put(MDB_cursor *mc, MDB_val *key, MDB_val *data,
     unsigned int flags)
 {
+	enum { MDB_NO_ROOT = MDB_LAST_ERRCODE+10 }; /* internal code */
 	MDB_env		*env;
 	MDB_node	*leaf = NULL;
-	MDB_page	*fp, *mp, *sub_root = NULL;
+	MDB_page	*fp, *mp;
 	uint16_t	fp_flags;
 	MDB_val		xdata, *rdata, dkey, olddata;
 	MDB_db dummy;
@@ -6321,7 +6173,7 @@ mdb_cursor_put(MDB_cursor *mc, MDB_val *key, MDB_val *data,
 	nospill = flags & MDB_NOSPILL;
 	flags &= ~MDB_NOSPILL;
 
-	if (mc->mc_txn->mt_flags & (MDB_TXN_RDONLY|MDB_TXN_BLOCKED))
+	if (mc->mc_txn->mt_flags & (MDB_TXN_RDONLY|MDB_TXN_ERROR))
 		return (mc->mc_txn->mt_flags & MDB_TXN_RDONLY) ? EACCES : MDB_BAD_TXN;
 
 	if (key->mv_size-1 >= ENV_MAXKEY(env))
@@ -6446,18 +6298,16 @@ fix_parent:
 			 * update branch key if there is a parent page
 			 */
 			if (mc->mc_top && !mc->mc_ki[mc->mc_top]) {
-				unsigned short dtop = 1;
+				unsigned short top = mc->mc_top;
 				mc->mc_top--;
 				/* slot 0 is always an empty key, find real slot */
-				while (mc->mc_top && !mc->mc_ki[mc->mc_top]) {
+				while (mc->mc_top && !mc->mc_ki[mc->mc_top])
 					mc->mc_top--;
-					dtop++;
-				}
 				if (mc->mc_ki[mc->mc_top])
 					rc2 = mdb_update_key(mc, key);
 				else
 					rc2 = MDB_SUCCESS;
-				mc->mc_top += dtop;
+				mc->mc_top = top;
 				if (rc2)
 					return rc2;
 			}
@@ -6482,18 +6332,17 @@ more:
 
 			/* Was a single item before, must convert now */
 			if (!F_ISSET(leaf->mn_flags, F_DUPDATA)) {
-				MDB_cmp_func *dcmp;
 				/* Just overwrite the current item */
 				if (flags == MDB_CURRENT)
 					goto current;
-				dcmp = mc->mc_dbx->md_dcmp;
+
 #if UINT_MAX < SIZE_MAX
-				if (dcmp == mdb_cmp_int && olddata.mv_size == sizeof(size_t))
-					dcmp = mdb_cmp_clong;
+				if (mc->mc_dbx->md_dcmp == mdb_cmp_int && olddata.mv_size == sizeof(size_t))
+					mc->mc_dbx->md_dcmp = mdb_cmp_clong;
 #endif
 				/* does data match? */
-				if (!dcmp(data, &olddata)) {
-					if (flags & (MDB_NODUPDATA|MDB_APPENDDUP))
+				if (!mc->mc_dbx->md_dcmp(data, &olddata)) {
+					if (flags & MDB_NODUPDATA)
 						return MDB_KEYEXIST;
 					/* overwrite it */
 					goto current;
@@ -6574,7 +6423,6 @@ prep_subDB:
 					offset = env->me_psize - olddata.mv_size;
 					flags |= F_DUPDATA|F_SUBDATA;
 					dummy.md_root = mp->mp_pgno;
-					sub_root = mp;
 			}
 			if (mp != fp) {
 				mp->mp_flags = fp_flags | P_DIRTY;
@@ -6599,9 +6447,6 @@ prep_subDB:
 			goto new_sub;
 		}
 current:
-		/* LMDB passes F_SUBDATA in 'flags' to write a DB record */
-		if ((leaf->mn_flags ^ flags) & F_SUBDATA)
-			return MDB_INCOMPATIBLE;
 		/* overflow page overwrites need special handling */
 		if (F_ISSET(leaf->mn_flags, F_BIGDATA)) {
 			MDB_page *omp;
@@ -6638,7 +6483,6 @@ current:
 						return ENOMEM;
 					id2.mid = pg;
 					id2.mptr = np;
-					/* Note - this page is already counted in parent's dirty_room */
 					rc2 = mdb_mid2l_insert(mc->mc_txn->mt_u.dirty_list, &id2);
 					mdb_cassert(mc, rc2 == 0);
 					if (!(flags & MDB_RESERVE)) {
@@ -6695,7 +6539,7 @@ new_sub:
 	} else {
 		/* There is room already in this leaf page. */
 		rc = mdb_node_add(mc, mc->mc_ki[mc->mc_top], key, rdata, 0, nflags);
-		if (rc == 0) {
+		if (rc == 0 && insert_key) {
 			/* Adjust other cursors pointing to mp */
 			MDB_cursor *m2, *m3;
 			MDB_dbi dbi = mc->mc_dbi;
@@ -6707,15 +6551,10 @@ new_sub:
 					m3 = &m2->mc_xcursor->mx_cursor;
 				else
 					m3 = m2;
-				if (m3 == mc || m3->mc_snum < mc->mc_snum || m3->mc_pg[i] != mp) continue;
-				if (m3->mc_ki[i] >= mc->mc_ki[i] && insert_key) {
+				if (m3 == mc || m3->mc_snum < mc->mc_snum) continue;
+				if (m3->mc_pg[i] == mp && m3->mc_ki[i] >= mc->mc_ki[i]) {
 					m3->mc_ki[i]++;
 				}
-				if (m3->mc_xcursor && (m3->mc_xcursor->mx_cursor.mc_flags & C_INITIALIZED)) {
-					MDB_node *n2 = NODEPTR(mp, m3->mc_ki[i]);
-					if ((n2->mn_flags & (F_SUBDATA|F_DUPDATA)) == F_DUPDATA)
-						m3->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(n2);
-				}
 			}
 		}
 	}
@@ -6727,7 +6566,7 @@ new_sub:
 		 * DB are all zero size.
 		 */
 		if (do_sub) {
-			int xflags, new_dupdata;
+			int xflags;
 			size_t ecount;
 put_sub:
 			xdata.mv_size = 0;
@@ -6740,38 +6579,27 @@ put_sub:
 				xflags = (flags & MDB_NODUPDATA) ?
 					MDB_NOOVERWRITE|MDB_NOSPILL : MDB_NOSPILL;
 			}
-			if (sub_root)
-				mc->mc_xcursor->mx_cursor.mc_pg[0] = sub_root;
-			new_dupdata = (int)dkey.mv_size;
 			/* converted, write the original data first */
 			if (dkey.mv_size) {
 				rc = mdb_cursor_put(&mc->mc_xcursor->mx_cursor, &dkey, &xdata, xflags);
 				if (rc)
 					goto bad_sub;
-				/* we've done our job */
-				dkey.mv_size = 0;
-			}
-			if (!(leaf->mn_flags & F_SUBDATA) || sub_root) {
-				/* Adjust other cursors pointing to mp */
-				MDB_cursor *m2;
-				MDB_xcursor *mx = mc->mc_xcursor;
-				unsigned i = mc->mc_top;
-				MDB_page *mp = mc->mc_pg[i];
-				int nkeys = NUMKEYS(mp);
-
-				for (m2 = mc->mc_txn->mt_cursors[mc->mc_dbi]; m2; m2=m2->mc_next) {
-					if (m2 == mc || m2->mc_snum < mc->mc_snum) continue;
-					if (!(m2->mc_flags & C_INITIALIZED)) continue;
-					if (m2->mc_pg[i] == mp) {
-						if (m2->mc_ki[i] == mc->mc_ki[i]) {
-							mdb_xcursor_init2(m2, mx, new_dupdata);
-						} else if (!insert_key && m2->mc_ki[i] < nkeys) {
-							MDB_node *n2 = NODEPTR(mp, m2->mc_ki[i]);
-							if ((n2->mn_flags & (F_SUBDATA|F_DUPDATA)) == F_DUPDATA)
-								m2->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(n2);
+				{
+					/* Adjust other cursors pointing to mp */
+					MDB_cursor *m2;
+					unsigned i = mc->mc_top;
+					MDB_page *mp = mc->mc_pg[i];
+
+					for (m2 = mc->mc_txn->mt_cursors[mc->mc_dbi]; m2; m2=m2->mc_next) {
+						if (m2 == mc || m2->mc_snum < mc->mc_snum) continue;
+						if (!(m2->mc_flags & C_INITIALIZED)) continue;
+						if (m2->mc_pg[i] == mp && m2->mc_ki[i] == mc->mc_ki[i]) {
+							mdb_xcursor_init1(m2, leaf);
 						}
 					}
 				}
+				/* we've done our job */
+				dkey.mv_size = 0;
 			}
 			ecount = mc->mc_xcursor->mx_db.md_entries;
 			if (flags & MDB_APPENDDUP)
@@ -6823,7 +6651,7 @@ mdb_cursor_del(MDB_cursor *mc, unsigned int flags)
 	MDB_page	*mp;
 	int rc;
 
-	if (mc->mc_txn->mt_flags & (MDB_TXN_RDONLY|MDB_TXN_BLOCKED))
+	if (mc->mc_txn->mt_flags & (MDB_TXN_RDONLY|MDB_TXN_ERROR))
 		return (mc->mc_txn->mt_flags & MDB_TXN_RDONLY) ? EACCES : MDB_BAD_TXN;
 
 	if (!(mc->mc_flags & C_INITIALIZED))
@@ -6848,7 +6676,6 @@ mdb_cursor_del(MDB_cursor *mc, unsigned int flags)
 		if (flags & MDB_NODUPDATA) {
 			/* mdb_cursor_del0() will subtract the final entry */
 			mc->mc_db->md_entries -= mc->mc_xcursor->mx_db.md_entries - 1;
-			mc->mc_xcursor->mx_cursor.mc_flags &= ~C_INITIALIZED;
 		} else {
 			if (!F_ISSET(leaf->mn_flags, F_SUBDATA)) {
 				mc->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
@@ -6868,25 +6695,17 @@ mdb_cursor_del(MDB_cursor *mc, unsigned int flags)
 					mdb_node_shrink(mp, mc->mc_ki[mc->mc_top]);
 					leaf = NODEPTR(mp, mc->mc_ki[mc->mc_top]);
 					mc->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
-					/* fix other sub-DB cursors pointed at fake pages on this page */
+					/* fix other sub-DB cursors pointed at this fake page */
 					for (m2 = mc->mc_txn->mt_cursors[mc->mc_dbi]; m2; m2=m2->mc_next) {
 						if (m2 == mc || m2->mc_snum < mc->mc_snum) continue;
-						if (!(m2->mc_flags & C_INITIALIZED)) continue;
-						if (m2->mc_pg[mc->mc_top] == mp) {
-							if (m2->mc_ki[mc->mc_top] == mc->mc_ki[mc->mc_top]) {
-								m2->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
-							} else {
-								MDB_node *n2 = NODEPTR(mp, m2->mc_ki[mc->mc_top]);
-								if (!(n2->mn_flags & F_SUBDATA))
-									m2->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(n2);
-							}
-						}
+						if (m2->mc_pg[mc->mc_top] == mp &&
+							m2->mc_ki[mc->mc_top] == mc->mc_ki[mc->mc_top])
+							m2->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
 					}
 				}
 				mc->mc_db->md_entries--;
+				mc->mc_flags |= C_DEL;
 				return rc;
-			} else {
-				mc->mc_xcursor->mx_cursor.mc_flags &= ~C_INITIALIZED;
 			}
 			/* otherwise fall thru and delete the sub-DB */
 		}
@@ -6898,11 +6717,6 @@ mdb_cursor_del(MDB_cursor *mc, unsigned int flags)
 				goto fail;
 		}
 	}
-	/* LMDB passes F_SUBDATA in 'flags' to delete a DB record */
-	else if ((leaf->mn_flags ^ flags) & F_SUBDATA) {
-		rc = MDB_INCOMPATIBLE;
-		goto fail;
-	}
 
 	/* add overflow pages to free list */
 	if (F_ISSET(leaf->mn_flags, F_BIGDATA)) {
@@ -7034,7 +6848,6 @@ mdb_node_add(MDB_cursor *mc, indx_t indx,
 	MDB_node	*node;
 	MDB_page	*mp = mc->mc_pg[mc->mc_top];
 	MDB_page	*ofp = NULL;		/* overflow page */
-	void		*ndata;
 	DKBUF;
 
 	mdb_cassert(mc, mp->mp_upper >= mp->mp_lower);
@@ -7065,7 +6878,7 @@ mdb_node_add(MDB_cursor *mc, indx_t indx,
 	if (key != NULL)
 		node_size += key->mv_size;
 	if (IS_LEAF(mp)) {
-		mdb_cassert(mc, key && data);
+		mdb_cassert(mc, data);
 		if (F_ISSET(flags, F_BIGDATA)) {
 			/* Data already on overflow page. */
 			node_size += sizeof(pgno_t);
@@ -7116,21 +6929,23 @@ update:
 		memcpy(NODEKEY(node), key->mv_data, key->mv_size);
 
 	if (IS_LEAF(mp)) {
-		ndata = NODEDATA(node);
+		mdb_cassert(mc, key);
 		if (ofp == NULL) {
 			if (F_ISSET(flags, F_BIGDATA))
-				memcpy(ndata, data->mv_data, sizeof(pgno_t));
+				memcpy(node->mn_data + key->mv_size, data->mv_data,
+				    sizeof(pgno_t));
 			else if (F_ISSET(flags, MDB_RESERVE))
-				data->mv_data = ndata;
+				data->mv_data = node->mn_data + key->mv_size;
 			else
-				memcpy(ndata, data->mv_data, data->mv_size);
+				memcpy(node->mn_data + key->mv_size, data->mv_data,
+				    data->mv_size);
 		} else {
-			memcpy(ndata, &ofp->mp_pgno, sizeof(pgno_t));
-			ndata = METADATA(ofp);
+			memcpy(node->mn_data + key->mv_size, &ofp->mp_pgno,
+			    sizeof(pgno_t));
 			if (F_ISSET(flags, MDB_RESERVE))
-				data->mv_data = ndata;
+				data->mv_data = METADATA(ofp);
 			else
-				memcpy(ndata, data->mv_data, data->mv_size);
+				memcpy(METADATA(ofp), data->mv_data, data->mv_size);
 		}
 	}
 
@@ -7212,38 +7027,45 @@ mdb_node_shrink(MDB_page *mp, indx_t indx)
 	MDB_node *node;
 	MDB_page *sp, *xp;
 	char *base;
-	indx_t delta, nsize, len, ptr;
-	int i;
+	int nsize, delta;
+	indx_t		 i, numkeys, ptr;
 
 	node = NODEPTR(mp, indx);
 	sp = (MDB_page *)NODEDATA(node);
 	delta = SIZELEFT(sp);
-	nsize = NODEDSZ(node) - delta;
+	xp = (MDB_page *)((char *)sp + delta);
 
-	/* Prepare to shift upward, set len = length(subpage part to shift) */
+	/* shift subpage upward */
 	if (IS_LEAF2(sp)) {
-		len = nsize;
+		nsize = NUMKEYS(sp) * sp->mp_pad;
 		if (nsize & 1)
 			return;		/* do not make the node uneven-sized */
+		memmove(METADATA(xp), METADATA(sp), nsize);
 	} else {
-		xp = (MDB_page *)((char *)sp + delta); /* destination subpage */
-		for (i = NUMKEYS(sp); --i >= 0; )
+		int i;
+		numkeys = NUMKEYS(sp);
+		for (i=numkeys-1; i>=0; i--)
 			xp->mp_ptrs[i] = sp->mp_ptrs[i] - delta;
-		len = PAGEHDRSZ;
 	}
-	sp->mp_upper = sp->mp_lower;
-	COPY_PGNO(sp->mp_pgno, mp->mp_pgno);
-	SETDSZ(node, nsize);
+	xp->mp_upper = sp->mp_lower;
+	xp->mp_lower = sp->mp_lower;
+	xp->mp_flags = sp->mp_flags;
+	xp->mp_pad = sp->mp_pad;
+	COPY_PGNO(xp->mp_pgno, mp->mp_pgno);
 
-	/* Shift <lower nodes...initial part of subpage> upward */
-	base = (char *)mp + mp->mp_upper + PAGEBASE;
-	memmove(base + delta, base, (char *)sp + len - base);
+	nsize = NODEDSZ(node) - delta;
+	SETDSZ(node, nsize);
 
+	/* shift lower nodes upward */
 	ptr = mp->mp_ptrs[indx];
-	for (i = NUMKEYS(mp); --i >= 0; ) {
+	numkeys = NUMKEYS(mp);
+	for (i = 0; i < numkeys; i++) {
 		if (mp->mp_ptrs[i] <= ptr)
 			mp->mp_ptrs[i] += delta;
 	}
+
+	base = (char *)mp + mp->mp_upper + PAGEBASE;
+	memmove(base + delta, base, ptr - mp->mp_upper + NODESIZE + NODEKSZ(node));
 	mp->mp_upper += delta;
 }
 
@@ -7296,7 +7118,7 @@ mdb_xcursor_init1(MDB_cursor *mc, MDB_node *node)
 		mx->mx_cursor.mc_flags = C_SUB;
 	} else {
 		MDB_page *fp = NODEDATA(node);
-		mx->mx_db.md_pad = 0;
+		mx->mx_db.md_pad = mc->mc_pg[mc->mc_top]->mp_pad;
 		mx->mx_db.md_flags = 0;
 		mx->mx_db.md_depth = 1;
 		mx->mx_db.md_branch_pages = 0;
@@ -7318,45 +7140,13 @@ mdb_xcursor_init1(MDB_cursor *mc, MDB_node *node)
 	}
 	DPRINTF(("Sub-db -%u root page %"Z"u", mx->mx_cursor.mc_dbi,
 		mx->mx_db.md_root));
-	mx->mx_dbflag = DB_VALID|DB_USRVALID|DB_DIRTY; /* DB_DIRTY guides mdb_cursor_touch */
+	mx->mx_dbflag = DB_VALID|DB_DIRTY; /* DB_DIRTY guides mdb_cursor_touch */
 #if UINT_MAX < SIZE_MAX
 	if (mx->mx_dbx.md_cmp == mdb_cmp_int && mx->mx_db.md_pad == sizeof(size_t))
 		mx->mx_dbx.md_cmp = mdb_cmp_clong;
 #endif
 }
 
-
-/** Fixup a sorted-dups cursor due to underlying update.
- *	Sets up some fields that depend on the data from the main cursor.
- *	Almost the same as init1, but skips initialization steps if the
- *	xcursor had already been used.
- * @param[in] mc The main cursor whose sorted-dups cursor is to be fixed up.
- * @param[in] src_mx The xcursor of an up-to-date cursor.
- * @param[in] new_dupdata True if converting from a non-#F_DUPDATA item.
- */
-static void
-mdb_xcursor_init2(MDB_cursor *mc, MDB_xcursor *src_mx, int new_dupdata)
-{
-	MDB_xcursor *mx = mc->mc_xcursor;
-
-	if (new_dupdata) {
-		mx->mx_cursor.mc_snum = 1;
-		mx->mx_cursor.mc_top = 0;
-		mx->mx_cursor.mc_flags |= C_INITIALIZED;
-		mx->mx_cursor.mc_ki[0] = 0;
-		mx->mx_dbflag = DB_VALID|DB_USRVALID|DB_DIRTY; /* DB_DIRTY guides mdb_cursor_touch */
-#if UINT_MAX < SIZE_MAX
-		mx->mx_dbx.md_cmp = src_mx->mx_dbx.md_cmp;
-#endif
-	} else if (!(mx->mx_cursor.mc_flags & C_INITIALIZED)) {
-		return;
-	}
-	mx->mx_db = src_mx->mx_db;
-	mx->mx_cursor.mc_pg[0] = src_mx->mx_cursor.mc_pg[0];
-	DPRINTF(("Sub-db -%u root page %"Z"u", mx->mx_cursor.mc_dbi,
-		mx->mx_db.md_root));
-}
-
 /** Initialize a cursor for a given transaction and database. */
 static void
 mdb_cursor_init(MDB_cursor *mc, MDB_txn *txn, MDB_dbi dbi, MDB_xcursor *mx)
@@ -7371,7 +7161,6 @@ mdb_cursor_init(MDB_cursor *mc, MDB_txn *txn, MDB_dbi dbi, MDB_xcursor *mx)
 	mc->mc_snum = 0;
 	mc->mc_top = 0;
 	mc->mc_pg[0] = 0;
-	mc->mc_ki[0] = 0;
 	mc->mc_flags = 0;
 	if (txn->mt_dbs[dbi].md_flags & MDB_DUPSORT) {
 		mdb_tassert(txn, mx != NULL);
@@ -7391,13 +7180,14 @@ mdb_cursor_open(MDB_txn *txn, MDB_dbi dbi, MDB_cursor **ret)
 	MDB_cursor	*mc;
 	size_t size = sizeof(MDB_cursor);
 
-	if (!ret || !TXN_DBI_EXIST(txn, dbi, DB_VALID))
+	if (!ret || !TXN_DBI_EXIST(txn, dbi))
 		return EINVAL;
 
-	if (txn->mt_flags & MDB_TXN_BLOCKED)
+	if (txn->mt_flags & MDB_TXN_ERROR)
 		return MDB_BAD_TXN;
 
-	if (dbi == FREE_DBI && !F_ISSET(txn->mt_flags, MDB_TXN_RDONLY))
+	/* Allow read access to the freelist */
+	if (!dbi && !F_ISSET(txn->mt_flags, MDB_TXN_RDONLY))
 		return EINVAL;
 
 	if (txn->mt_dbs[dbi].md_flags & MDB_DUPSORT)
@@ -7422,13 +7212,13 @@ mdb_cursor_open(MDB_txn *txn, MDB_dbi dbi, MDB_cursor **ret)
 int
 mdb_cursor_renew(MDB_txn *txn, MDB_cursor *mc)
 {
-	if (!mc || !TXN_DBI_EXIST(txn, mc->mc_dbi, DB_VALID))
+	if (!mc || !TXN_DBI_EXIST(txn, mc->mc_dbi))
 		return EINVAL;
 
 	if ((mc->mc_flags & C_UNTRACK) || txn->mt_cursors)
 		return EINVAL;
 
-	if (txn->mt_flags & MDB_TXN_BLOCKED)
+	if (txn->mt_flags & MDB_TXN_ERROR)
 		return MDB_BAD_TXN;
 
 	mdb_cursor_init(mc, txn, mc->mc_dbi, mc->mc_xcursor);
@@ -7447,7 +7237,7 @@ mdb_cursor_count(MDB_cursor *mc, size_t *countp)
 	if (mc->mc_xcursor == NULL)
 		return MDB_INCOMPATIBLE;
 
-	if (mc->mc_txn->mt_flags & MDB_TXN_BLOCKED)
+	if (mc->mc_txn->mt_flags & MDB_TXN_ERROR)
 		return MDB_BAD_TXN;
 
 	if (!(mc->mc_flags & C_INITIALIZED))
@@ -7573,26 +7363,10 @@ mdb_update_key(MDB_cursor *mc, MDB_val *key)
 static void
 mdb_cursor_copy(const MDB_cursor *csrc, MDB_cursor *cdst);
 
-/** Perform \b act while tracking temporary cursor \b mn */
-#define WITH_CURSOR_TRACKING(mn, act) do { \
-	MDB_cursor dummy, *tracked, **tp = &(mn).mc_txn->mt_cursors[mn.mc_dbi]; \
-	if ((mn).mc_flags & C_SUB) { \
-		dummy.mc_flags =  C_INITIALIZED; \
-		dummy.mc_xcursor = (MDB_xcursor *)&(mn);	\
-		tracked = &dummy; \
-	} else { \
-		tracked = &(mn); \
-	} \
-	tracked->mc_next = *tp; \
-	*tp = tracked; \
-	{ act; } \
-	*tp = tracked->mc_next; \
-} while (0)
-
 /** Move a node from csrc to cdst.
  */
 static int
-mdb_node_move(MDB_cursor *csrc, MDB_cursor *cdst, int fromleft)
+mdb_node_move(MDB_cursor *csrc, MDB_cursor *cdst)
 {
 	MDB_node		*srcnode;
 	MDB_val		 key, data;
@@ -7644,7 +7418,6 @@ mdb_node_move(MDB_cursor *csrc, MDB_cursor *cdst, int fromleft)
 		data.mv_size = NODEDSZ(srcnode);
 		data.mv_data = NODEDATA(srcnode);
 	}
-	mn.mc_xcursor = NULL;
 	if (IS_BRANCH(cdst->mc_pg[cdst->mc_top]) && cdst->mc_ki[cdst->mc_top] == 0) {
 		unsigned int snum = cdst->mc_snum;
 		MDB_node *s2;
@@ -7691,64 +7464,18 @@ mdb_node_move(MDB_cursor *csrc, MDB_cursor *cdst, int fromleft)
 		/* Adjust other cursors pointing to mp */
 		MDB_cursor *m2, *m3;
 		MDB_dbi dbi = csrc->mc_dbi;
-		MDB_page *mpd, *mps;
-
-		mps = csrc->mc_pg[csrc->mc_top];
-		/* If we're adding on the left, bump others up */
-		if (fromleft) {
-			mpd = cdst->mc_pg[csrc->mc_top];
-			for (m2 = csrc->mc_txn->mt_cursors[dbi]; m2; m2=m2->mc_next) {
-				if (csrc->mc_flags & C_SUB)
-					m3 = &m2->mc_xcursor->mx_cursor;
-				else
-					m3 = m2;
-				if (!(m3->mc_flags & C_INITIALIZED) || m3->mc_top < csrc->mc_top)
-					continue;
-				if (m3 != cdst &&
-					m3->mc_pg[csrc->mc_top] == mpd &&
-					m3->mc_ki[csrc->mc_top] >= cdst->mc_ki[csrc->mc_top]) {
-					m3->mc_ki[csrc->mc_top]++;
-				}
-				if (m3 !=csrc &&
-					m3->mc_pg[csrc->mc_top] == mps &&
-					m3->mc_ki[csrc->mc_top] == csrc->mc_ki[csrc->mc_top]) {
-					m3->mc_pg[csrc->mc_top] = cdst->mc_pg[cdst->mc_top];
-					m3->mc_ki[csrc->mc_top] = cdst->mc_ki[cdst->mc_top];
-					m3->mc_ki[csrc->mc_top-1]++;
-				}
-				if (m3->mc_xcursor && (m3->mc_xcursor->mx_cursor.mc_flags & C_INITIALIZED) &&
-					IS_LEAF(mps)) {
-					MDB_node *node = NODEPTR(m3->mc_pg[csrc->mc_top], m3->mc_ki[csrc->mc_top]);
-					if ((node->mn_flags & (F_DUPDATA|F_SUBDATA)) == F_DUPDATA)
-						m3->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(node);
-				}
-			}
-		} else
-		/* Adding on the right, bump others down */
-		{
-			for (m2 = csrc->mc_txn->mt_cursors[dbi]; m2; m2=m2->mc_next) {
-				if (csrc->mc_flags & C_SUB)
-					m3 = &m2->mc_xcursor->mx_cursor;
-				else
-					m3 = m2;
-				if (m3 == csrc) continue;
-				if (!(m3->mc_flags & C_INITIALIZED) || m3->mc_top < csrc->mc_top)
-					continue;
-				if (m3->mc_pg[csrc->mc_top] == mps) {
-					if (!m3->mc_ki[csrc->mc_top]) {
-						m3->mc_pg[csrc->mc_top] = cdst->mc_pg[cdst->mc_top];
-						m3->mc_ki[csrc->mc_top] = cdst->mc_ki[cdst->mc_top];
-						m3->mc_ki[csrc->mc_top-1]--;
-					} else {
-						m3->mc_ki[csrc->mc_top]--;
-					}
-					if (m3->mc_xcursor && (m3->mc_xcursor->mx_cursor.mc_flags & C_INITIALIZED) &&
-						IS_LEAF(mps)) {
-						MDB_node *node = NODEPTR(m3->mc_pg[csrc->mc_top], m3->mc_ki[csrc->mc_top]);
-						if ((node->mn_flags & (F_DUPDATA|F_SUBDATA)) == F_DUPDATA)
-							m3->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(node);
-					}
-				}
+		MDB_page *mp = csrc->mc_pg[csrc->mc_top];
+
+		for (m2 = csrc->mc_txn->mt_cursors[dbi]; m2; m2=m2->mc_next) {
+			if (csrc->mc_flags & C_SUB)
+				m3 = &m2->mc_xcursor->mx_cursor;
+			else
+				m3 = m2;
+			if (m3 == csrc) continue;
+			if (m3->mc_pg[csrc->mc_top] == mp && m3->mc_ki[csrc->mc_top] ==
+				csrc->mc_ki[csrc->mc_top]) {
+				m3->mc_pg[csrc->mc_top] = cdst->mc_pg[cdst->mc_top];
+				m3->mc_ki[csrc->mc_top] = cdst->mc_ki[cdst->mc_top];
 			}
 		}
 	}
@@ -7769,10 +7496,7 @@ mdb_node_move(MDB_cursor *csrc, MDB_cursor *cdst, int fromleft)
 			mdb_cursor_copy(csrc, &mn);
 			mn.mc_snum--;
 			mn.mc_top--;
-			/* We want mdb_rebalance to find mn when doing fixups */
-			WITH_CURSOR_TRACKING(mn,
-				rc = mdb_update_key(&mn, &key));
-			if (rc)
+			if ((rc = mdb_update_key(&mn, &key)) != MDB_SUCCESS)
 				return rc;
 		}
 		if (IS_BRANCH(csrc->mc_pg[csrc->mc_top])) {
@@ -7800,10 +7524,7 @@ mdb_node_move(MDB_cursor *csrc, MDB_cursor *cdst, int fromleft)
 			mdb_cursor_copy(cdst, &mn);
 			mn.mc_snum--;
 			mn.mc_top--;
-			/* We want mdb_rebalance to find mn when doing fixups */
-			WITH_CURSOR_TRACKING(mn,
-				rc = mdb_update_key(&mn, &key));
-			if (rc)
+			if ((rc = mdb_update_key(&mn, &key)) != MDB_SUCCESS)
 				return rc;
 		}
 		if (IS_BRANCH(cdst->mc_pg[cdst->mc_top])) {
@@ -7813,7 +7534,7 @@ mdb_node_move(MDB_cursor *csrc, MDB_cursor *cdst, int fromleft)
 			cdst->mc_ki[cdst->mc_top] = 0;
 			rc = mdb_update_key(cdst, &nullkey);
 			cdst->mc_ki[cdst->mc_top] = ix;
-			mdb_cassert(cdst, rc == MDB_SUCCESS);
+			mdb_cassert(csrc, rc == MDB_SUCCESS);
 		}
 	}
 
@@ -7850,9 +7571,6 @@ mdb_page_merge(MDB_cursor *csrc, MDB_cursor *cdst)
 	if ((rc = mdb_page_touch(cdst)))
 		return rc;
 
-	/* get dst page again now that we've touched it. */
-	pdst = cdst->mc_pg[cdst->mc_top];
-
 	/* Move all nodes from src to dst.
 	 */
 	j = nkeys = NUMKEYS(pdst);
@@ -7872,7 +7590,6 @@ mdb_page_merge(MDB_cursor *csrc, MDB_cursor *cdst)
 				MDB_cursor mn;
 				MDB_node *s2;
 				mdb_cursor_copy(csrc, &mn);
-				mn.mc_xcursor = NULL;
 				/* must find the lowest key below src */
 				rc = mdb_page_search_lowest(&mn);
 				if (rc)
@@ -7931,7 +7648,6 @@ mdb_page_merge(MDB_cursor *csrc, MDB_cursor *cdst)
 		/* Adjust other cursors pointing to mp */
 		MDB_cursor *m2, *m3;
 		MDB_dbi dbi = csrc->mc_dbi;
-		unsigned int top = csrc->mc_top;
 
 		for (m2 = csrc->mc_txn->mt_cursors[dbi]; m2; m2=m2->mc_next) {
 			if (csrc->mc_flags & C_SUB)
@@ -7940,19 +7656,9 @@ mdb_page_merge(MDB_cursor *csrc, MDB_cursor *cdst)
 				m3 = m2;
 			if (m3 == csrc) continue;
 			if (m3->mc_snum < csrc->mc_snum) continue;
-			if (m3->mc_pg[top] == psrc) {
-				m3->mc_pg[top] = pdst;
-				m3->mc_ki[top] += nkeys;
-				m3->mc_ki[top-1] = cdst->mc_ki[top-1];
-			} else if (m3->mc_pg[top-1] == csrc->mc_pg[top-1] &&
-				m3->mc_ki[top-1] > csrc->mc_ki[top-1]) {
-				m3->mc_ki[top-1]--;
-			}
-			if (m3->mc_xcursor && (m3->mc_xcursor->mx_cursor.mc_flags & C_INITIALIZED) &&
-				IS_LEAF(psrc)) {
-				MDB_node *node = NODEPTR(m3->mc_pg[top], m3->mc_ki[top]);
-				if ((node->mn_flags & (F_DUPDATA|F_SUBDATA)) == F_DUPDATA)
-					m3->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(node);
+			if (m3->mc_pg[csrc->mc_top] == psrc) {
+				m3->mc_pg[csrc->mc_top] = pdst;
+				m3->mc_ki[csrc->mc_top] += nkeys;
 			}
 		}
 	}
@@ -7961,9 +7667,9 @@ mdb_page_merge(MDB_cursor *csrc, MDB_cursor *cdst)
 		uint16_t depth = cdst->mc_db->md_depth;
 		mdb_cursor_pop(cdst);
 		rc = mdb_rebalance(cdst);
-		/* Did the tree height change? */
-		if (depth != cdst->mc_db->md_depth)
-			snum += cdst->mc_db->md_depth - depth;
+		/* Did the tree shrink? */
+		if (depth > cdst->mc_db->md_depth)
+			snum--;
 		cdst->mc_snum = snum;
 		cdst->mc_top = snum-1;
 	}
@@ -8002,24 +7708,18 @@ static int
 mdb_rebalance(MDB_cursor *mc)
 {
 	MDB_node	*node;
-	int rc, fromleft;
-	unsigned int ptop, minkeys, thresh;
+	int rc;
+	unsigned int ptop, minkeys;
 	MDB_cursor	mn;
 	indx_t oldki;
 
-	if (IS_BRANCH(mc->mc_pg[mc->mc_top])) {
-		minkeys = 2;
-		thresh = 1;
-	} else {
-		minkeys = 1;
-		thresh = FILL_THRESHOLD;
-	}
+	minkeys = 1 + (IS_BRANCH(mc->mc_pg[mc->mc_top]));
 	DPRINTF(("rebalancing %s page %"Z"u (has %u keys, %.1f%% full)",
 	    IS_LEAF(mc->mc_pg[mc->mc_top]) ? "leaf" : "branch",
 	    mdb_dbg_pgno(mc->mc_pg[mc->mc_top]), NUMKEYS(mc->mc_pg[mc->mc_top]),
 		(float)PAGEFILL(mc->mc_txn->mt_env, mc->mc_pg[mc->mc_top]) / 10));
 
-	if (PAGEFILL(mc->mc_txn->mt_env, mc->mc_pg[mc->mc_top]) >= thresh &&
+	if (PAGEFILL(mc->mc_txn->mt_env, mc->mc_pg[mc->mc_top]) >= FILL_THRESHOLD &&
 		NUMKEYS(mc->mc_pg[mc->mc_top]) >= minkeys) {
 		DPRINTF(("no need to rebalance page %"Z"u, above fill threshold",
 		    mdb_dbg_pgno(mc->mc_pg[mc->mc_top])));
@@ -8053,8 +7753,7 @@ mdb_rebalance(MDB_cursor *mc)
 						m3 = &m2->mc_xcursor->mx_cursor;
 					else
 						m3 = m2;
-					if (!(m3->mc_flags & C_INITIALIZED) || (m3->mc_snum < mc->mc_snum))
-						continue;
+					if (m3->mc_snum < mc->mc_snum) continue;
 					if (m3->mc_pg[0] == mp) {
 						m3->mc_snum = 0;
 						m3->mc_top = 0;
@@ -8089,16 +7788,14 @@ mdb_rebalance(MDB_cursor *mc)
 						m3 = &m2->mc_xcursor->mx_cursor;
 					else
 						m3 = m2;
-					if (m3 == mc) continue;
-					if (!(m3->mc_flags & C_INITIALIZED))
-						continue;
+					if (m3 == mc || m3->mc_snum < mc->mc_snum) continue;
 					if (m3->mc_pg[0] == mp) {
-						for (i=0; i<mc->mc_db->md_depth; i++) {
+						m3->mc_snum--;
+						m3->mc_top--;
+						for (i=0; i<m3->mc_snum; i++) {
 							m3->mc_pg[i] = m3->mc_pg[i+1];
 							m3->mc_ki[i] = m3->mc_ki[i+1];
 						}
-						m3->mc_snum--;
-						m3->mc_top--;
 					}
 				}
 			}
@@ -8135,7 +7832,6 @@ mdb_rebalance(MDB_cursor *mc)
 			return rc;
 		mn.mc_ki[mn.mc_top] = 0;
 		mc->mc_ki[mc->mc_top] = NUMKEYS(mc->mc_pg[mc->mc_top]);
-		fromleft = 0;
 	} else {
 		/* There is at least one neighbor to the left.
 		 */
@@ -8147,7 +7843,6 @@ mdb_rebalance(MDB_cursor *mc)
 			return rc;
 		mn.mc_ki[mn.mc_top] = NUMKEYS(mn.mc_pg[mn.mc_top]) - 1;
 		mc->mc_ki[mc->mc_top] = 0;
-		fromleft = 1;
 	}
 
 	DPRINTF(("found neighbor page %"Z"u (%u keys, %.1f%% full)",
@@ -8158,21 +7853,19 @@ mdb_rebalance(MDB_cursor *mc)
 	 * move one key from it. Otherwise we should try to merge them.
 	 * (A branch page must never have less than 2 keys.)
 	 */
-	if (PAGEFILL(mc->mc_txn->mt_env, mn.mc_pg[mn.mc_top]) >= thresh && NUMKEYS(mn.mc_pg[mn.mc_top]) > minkeys) {
-		rc = mdb_node_move(&mn, mc, fromleft);
-		if (fromleft) {
-			/* if we inserted on left, bump position up */
+	minkeys = 1 + (IS_BRANCH(mn.mc_pg[mn.mc_top]));
+	if (PAGEFILL(mc->mc_txn->mt_env, mn.mc_pg[mn.mc_top]) >= FILL_THRESHOLD && NUMKEYS(mn.mc_pg[mn.mc_top]) > minkeys) {
+		rc = mdb_node_move(&mn, mc);
+		if (mc->mc_ki[ptop]) {
 			oldki++;
 		}
 	} else {
-		if (!fromleft) {
+		if (mc->mc_ki[ptop] == 0) {
 			rc = mdb_page_merge(&mn, mc);
 		} else {
 			oldki += NUMKEYS(mn.mc_pg[mn.mc_top]);
 			mn.mc_ki[mn.mc_top] += mc->mc_ki[mn.mc_top] + 1;
-			/* We want mdb_rebalance to find mn when doing fixups */
-			WITH_CURSOR_TRACKING(mn,
-				rc = mdb_page_merge(mc, &mn));
+			rc = mdb_page_merge(mc, &mn);
 			mdb_cursor_copy(&mn, mc);
 		}
 		mc->mc_flags &= ~C_EOF;
@@ -8189,59 +7882,43 @@ mdb_cursor_del0(MDB_cursor *mc)
 	MDB_page *mp;
 	indx_t ki;
 	unsigned int nkeys;
-	MDB_cursor *m2, *m3;
-	MDB_dbi dbi = mc->mc_dbi;
 
 	ki = mc->mc_ki[mc->mc_top];
-	mp = mc->mc_pg[mc->mc_top];
 	mdb_node_del(mc, mc->mc_db->md_pad);
 	mc->mc_db->md_entries--;
-	{
-		/* Adjust other cursors pointing to mp */
-		for (m2 = mc->mc_txn->mt_cursors[dbi]; m2; m2=m2->mc_next) {
-			m3 = (mc->mc_flags & C_SUB) ? &m2->mc_xcursor->mx_cursor : m2;
-			if (! (m2->mc_flags & m3->mc_flags & C_INITIALIZED))
-				continue;
-			if (m3 == mc || m3->mc_snum < mc->mc_snum)
-				continue;
-			if (m3->mc_pg[mc->mc_top] == mp) {
-				if (m3->mc_ki[mc->mc_top] == ki) {
-					m3->mc_flags |= C_DEL;
-					if (mc->mc_db->md_flags & MDB_DUPSORT)
-						m3->mc_xcursor->mx_cursor.mc_flags &= ~C_INITIALIZED;
-				} else if (m3->mc_ki[mc->mc_top] > ki) {
-					m3->mc_ki[mc->mc_top]--;
-				}
-				if (m3->mc_xcursor && (m3->mc_xcursor->mx_cursor.mc_flags & C_INITIALIZED)) {
-					MDB_node *node = NODEPTR(m3->mc_pg[mc->mc_top], m3->mc_ki[mc->mc_top]);
-					if ((node->mn_flags & (F_DUPDATA|F_SUBDATA)) == F_DUPDATA)
-						m3->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(node);
-				}
-			}
-		}
-	}
 	rc = mdb_rebalance(mc);
 
 	if (rc == MDB_SUCCESS) {
-		/* DB is totally empty now, just bail out.
-		 * Other cursors adjustments were already done
-		 * by mdb_rebalance and aren't needed here.
-		 */
-		if (!mc->mc_snum)
-			return rc;
+		MDB_cursor *m2, *m3;
+		MDB_dbi dbi = mc->mc_dbi;
 
 		mp = mc->mc_pg[mc->mc_top];
 		nkeys = NUMKEYS(mp);
 
+		/* if mc points past last node in page, find next sibling */
+		if (mc->mc_ki[mc->mc_top] >= nkeys) {
+			rc = mdb_cursor_sibling(mc, 1);
+			if (rc == MDB_NOTFOUND) {
+				mc->mc_flags |= C_EOF;
+				rc = MDB_SUCCESS;
+			}
+		}
+
 		/* Adjust other cursors pointing to mp */
 		for (m2 = mc->mc_txn->mt_cursors[dbi]; !rc && m2; m2=m2->mc_next) {
 			m3 = (mc->mc_flags & C_SUB) ? &m2->mc_xcursor->mx_cursor : m2;
 			if (! (m2->mc_flags & m3->mc_flags & C_INITIALIZED))
 				continue;
-			if (m3->mc_snum < mc->mc_snum)
+			if (m3 == mc || m3->mc_snum < mc->mc_snum)
 				continue;
 			if (m3->mc_pg[mc->mc_top] == mp) {
-				/* if m3 points past last node in page, find next sibling */
+				if (m3->mc_ki[mc->mc_top] >= ki) {
+					m3->mc_flags |= C_DEL;
+					if (m3->mc_ki[mc->mc_top] > ki)
+						m3->mc_ki[mc->mc_top]--;
+					else if (mc->mc_db->md_flags & MDB_DUPSORT)
+						m3->mc_xcursor->mx_cursor.mc_flags |= C_EOF;
+				}
 				if (m3->mc_ki[mc->mc_top] >= nkeys) {
 					rc = mdb_cursor_sibling(m3, 1);
 					if (rc == MDB_NOTFOUND) {
@@ -8263,10 +7940,10 @@ int
 mdb_del(MDB_txn *txn, MDB_dbi dbi,
     MDB_val *key, MDB_val *data)
 {
-	if (!key || !TXN_DBI_EXIST(txn, dbi, DB_USRVALID))
+	if (!key || dbi == FREE_DBI || !TXN_DBI_EXIST(txn, dbi))
 		return EINVAL;
 
-	if (txn->mt_flags & (MDB_TXN_RDONLY|MDB_TXN_BLOCKED))
+	if (txn->mt_flags & (MDB_TXN_RDONLY|MDB_TXN_ERROR))
 		return (txn->mt_flags & MDB_TXN_RDONLY) ? EACCES : MDB_BAD_TXN;
 
 	if (!F_ISSET(txn->mt_dbs[dbi].md_flags, MDB_DUPSORT)) {
@@ -8359,27 +8036,20 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
 	/* Create a right sibling. */
 	if ((rc = mdb_page_new(mc, mp->mp_flags, 1, &rp)))
 		return rc;
-	rp->mp_pad = mp->mp_pad;
 	DPRINTF(("new right sibling: page %"Z"u", rp->mp_pgno));
 
-	/* Usually when splitting the root page, the cursor
-	 * height is 1. But when called from mdb_update_key,
-	 * the cursor height may be greater because it walks
-	 * up the stack while finding the branch slot to update.
-	 */
-	if (mc->mc_top < 1) {
+	if (mc->mc_snum < 2) {
 		if ((rc = mdb_page_new(mc, P_BRANCH, 1, &pp)))
 			goto done;
 		/* shift current top to make room for new parent */
-		for (i=mc->mc_snum; i>0; i--) {
-			mc->mc_pg[i] = mc->mc_pg[i-1];
-			mc->mc_ki[i] = mc->mc_ki[i-1];
-		}
+		mc->mc_pg[1] = mc->mc_pg[0];
+		mc->mc_ki[1] = mc->mc_ki[0];
 		mc->mc_pg[0] = pp;
 		mc->mc_ki[0] = 0;
 		mc->mc_db->md_root = pp->mp_pgno;
 		DPRINTF(("root split! new root = %"Z"u", pp->mp_pgno));
-		new_root = mc->mc_db->md_depth++;
+		mc->mc_db->md_depth++;
+		new_root = 1;
 
 		/* Add left (implicit) pointer. */
 		if ((rc = mdb_node_add(mc, 0, NULL, NULL, mp->mp_pgno, 0)) != MDB_SUCCESS) {
@@ -8390,16 +8060,16 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
 			mc->mc_db->md_depth--;
 			goto done;
 		}
-		mc->mc_snum++;
-		mc->mc_top++;
+		mc->mc_snum = 2;
+		mc->mc_top = 1;
 		ptop = 0;
 	} else {
 		ptop = mc->mc_top-1;
 		DPRINTF(("parent branch page is %"Z"u", mc->mc_pg[ptop]->mp_pgno));
 	}
 
+	mc->mc_flags |= C_SPLITTING;
 	mdb_cursor_copy(mc, &mn);
-	mn.mc_xcursor = NULL;
 	mn.mc_pg[mn.mc_top] = rp;
 	mn.mc_ki[ptop] = mc->mc_ki[ptop]+1;
 
@@ -8449,6 +8119,7 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
 				rp->mp_lower += sizeof(indx_t);
 				rp->mp_upper -= ksize - sizeof(indx_t);
 				mc->mc_ki[mc->mc_top] = x;
+				mc->mc_pg[mc->mc_top] = rp;
 			}
 		} else {
 			int psize, nsize, k;
@@ -8499,7 +8170,7 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
 				psize = 0;
 				if (newindx <= split_indx || newindx >= nkeys) {
 					i = 0; j = 1;
-					k = newindx >= nkeys ? nkeys : split_indx+1+IS_LEAF(mp);
+					k = newindx >= nkeys ? nkeys : split_indx+2;
 				} else {
 					i = nkeys; j = -1;
 					k = split_indx-1;
@@ -8541,18 +8212,21 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
 	/* Copy separator key to the parent.
 	 */
 	if (SIZELEFT(mn.mc_pg[ptop]) < mdb_branch_size(env, &sepkey)) {
-		int snum = mc->mc_snum;
 		mn.mc_snum--;
 		mn.mc_top--;
 		did_split = 1;
-		/* We want other splits to find mn when doing fixups */
-		WITH_CURSOR_TRACKING(mn,
-			rc = mdb_page_split(&mn, &sepkey, NULL, rp->mp_pgno, 0));
+		rc = mdb_page_split(&mn, &sepkey, NULL, rp->mp_pgno, 0);
 		if (rc)
 			goto done;
 
 		/* root split? */
-		if (mc->mc_snum > snum) {
+		if (mn.mc_snum == mc->mc_snum) {
+			mc->mc_pg[mc->mc_snum] = mc->mc_pg[mc->mc_top];
+			mc->mc_ki[mc->mc_snum] = mc->mc_ki[mc->mc_top];
+			mc->mc_pg[mc->mc_top] = mc->mc_pg[ptop];
+			mc->mc_ki[mc->mc_top] = mc->mc_ki[ptop];
+			mc->mc_snum++;
+			mc->mc_top++;
 			ptop++;
 		}
 		/* Right page might now have changed parent.
@@ -8578,6 +8252,7 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
 		rc = mdb_node_add(&mn, mn.mc_ki[ptop], &sepkey, NULL, rp->mp_pgno, 0);
 		mn.mc_top++;
 	}
+	mc->mc_flags ^= C_SPLITTING;
 	if (rc != MDB_SUCCESS) {
 		goto done;
 	}
@@ -8647,26 +8322,12 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
 		/* reset back to original page */
 		if (newindx < split_indx) {
 			mc->mc_pg[mc->mc_top] = mp;
-		} else {
-			mc->mc_pg[mc->mc_top] = rp;
-			mc->mc_ki[ptop]++;
-			/* Make sure mc_ki is still valid.
-			 */
-			if (mn.mc_pg[ptop] != mc->mc_pg[ptop] &&
-				mc->mc_ki[ptop] >= NUMKEYS(mc->mc_pg[ptop])) {
-				for (i=0; i<=ptop; i++) {
-					mc->mc_pg[i] = mn.mc_pg[i];
-					mc->mc_ki[i] = mn.mc_ki[i];
-				}
+			if (nflags & MDB_RESERVE) {
+				node = NODEPTR(mp, mc->mc_ki[mc->mc_top]);
+				if (!(node->mn_flags & F_BIGDATA))
+					newdata->mv_data = NODEDATA(node);
 			}
-		}
-		if (nflags & MDB_RESERVE) {
-			node = NODEPTR(mc->mc_pg[mc->mc_top], mc->mc_ki[mc->mc_top]);
-			if (!(node->mn_flags & F_BIGDATA))
-				newdata->mv_data = NODEDATA(node);
-		}
-	} else {
-		if (newindx >= split_indx) {
+		} else {
 			mc->mc_pg[mc->mc_top] = rp;
 			mc->mc_ki[ptop]++;
 			/* Make sure mc_ki is still valid.
@@ -8685,7 +8346,7 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
 		/* Adjust other cursors pointing to mp */
 		MDB_cursor *m2, *m3;
 		MDB_dbi dbi = mc->mc_dbi;
-		nkeys = NUMKEYS(mp);
+		int fixup = NUMKEYS(mp);
 
 		for (m2 = mc->mc_txn->mt_cursors[dbi]; m2; m2=m2->mc_next) {
 			if (mc->mc_flags & C_SUB)
@@ -8696,17 +8357,16 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
 				continue;
 			if (!(m2->mc_flags & m3->mc_flags & C_INITIALIZED))
 				continue;
+			if (m3->mc_flags & C_SPLITTING)
+				continue;
 			if (new_root) {
 				int k;
-				/* sub cursors may be on different DB */
-				if (m3->mc_pg[0] != mp)
-					continue;
 				/* root split */
-				for (k=new_root; k>=0; k--) {
+				for (k=m3->mc_top; k>=0; k--) {
 					m3->mc_ki[k+1] = m3->mc_ki[k];
 					m3->mc_pg[k+1] = m3->mc_pg[k];
 				}
-				if (m3->mc_ki[0] >= nkeys) {
+				if (m3->mc_ki[0] >= split_indx) {
 					m3->mc_ki[0] = 1;
 				} else {
 					m3->mc_ki[0] = 0;
@@ -8718,24 +8378,15 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
 			if (m3->mc_top >= mc->mc_top && m3->mc_pg[mc->mc_top] == mp) {
 				if (m3->mc_ki[mc->mc_top] >= newindx && !(nflags & MDB_SPLIT_REPLACE))
 					m3->mc_ki[mc->mc_top]++;
-				if (m3->mc_ki[mc->mc_top] >= nkeys) {
+				if (m3->mc_ki[mc->mc_top] >= fixup) {
 					m3->mc_pg[mc->mc_top] = rp;
-					m3->mc_ki[mc->mc_top] -= nkeys;
-					for (i=0; i<mc->mc_top; i++) {
-						m3->mc_ki[i] = mn.mc_ki[i];
-						m3->mc_pg[i] = mn.mc_pg[i];
-					}
+					m3->mc_ki[mc->mc_top] -= fixup;
+					m3->mc_ki[ptop] = mn.mc_ki[ptop];
 				}
 			} else if (!did_split && m3->mc_top >= ptop && m3->mc_pg[ptop] == mc->mc_pg[ptop] &&
 				m3->mc_ki[ptop] >= mc->mc_ki[ptop]) {
 				m3->mc_ki[ptop]++;
 			}
-			if (m3->mc_xcursor && (m3->mc_xcursor->mx_cursor.mc_flags & C_INITIALIZED) &&
-				IS_LEAF(mp)) {
-				MDB_node *node = NODEPTR(m3->mc_pg[mc->mc_top], m3->mc_ki[mc->mc_top]);
-				if ((node->mn_flags & (F_DUPDATA|F_SUBDATA)) == F_DUPDATA)
-					m3->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(node);
-			}
 		}
 	}
 	DPRINTF(("mp left: %d, rp left: %d", SIZELEFT(mp), SIZELEFT(rp)));
@@ -8754,23 +8405,15 @@ mdb_put(MDB_txn *txn, MDB_dbi dbi,
 {
 	MDB_cursor mc;
 	MDB_xcursor mx;
-	int rc;
 
-	if (!key || !data || !TXN_DBI_EXIST(txn, dbi, DB_USRVALID))
+	if (!key || !data || dbi == FREE_DBI || !TXN_DBI_EXIST(txn, dbi))
 		return EINVAL;
 
-	if (flags & ~(MDB_NOOVERWRITE|MDB_NODUPDATA|MDB_RESERVE|MDB_APPEND|MDB_APPENDDUP))
+	if ((flags & (MDB_NOOVERWRITE|MDB_NODUPDATA|MDB_RESERVE|MDB_APPEND|MDB_APPENDDUP)) != flags)
 		return EINVAL;
 
-	if (txn->mt_flags & (MDB_TXN_RDONLY|MDB_TXN_BLOCKED))
-		return (txn->mt_flags & MDB_TXN_RDONLY) ? EACCES : MDB_BAD_TXN;
-
 	mdb_cursor_init(&mc, txn, dbi, &mx);
-	mc.mc_next = txn->mt_cursors[dbi];
-	txn->mt_cursors[dbi] = &mc;
-	rc = mdb_cursor_put(&mc, key, data, flags);
-	txn->mt_cursors[dbi] = mc.mc_next;
-	return rc;
+	return mdb_cursor_put(&mc, key, data, flags);
 }
 
 #ifndef MDB_WBUF
@@ -8796,7 +8439,7 @@ typedef struct mdb_copy {
 } mdb_copy;
 
 	/** Dedicated writer thread for compacting copy. */
-static THREAD_RET ESECT CALL_CONV
+static THREAD_RET ESECT
 mdb_env_copythr(void *arg)
 {
 	mdb_copy *my = arg;
@@ -9073,7 +8716,7 @@ mdb_env_copyfd1(MDB_env *env, HANDLE fd)
 	my.mc_wlen[1] = 0;
 	my.mc_olen[0] = 0;
 	my.mc_olen[1] = 0;
-	my.mc_next_pgno = NUM_METAS;
+	my.mc_next_pgno = 2;
 	my.mc_status = 0;
 	my.mc_new = 1;
 	my.mc_toggle = 0;
@@ -9086,7 +8729,7 @@ mdb_env_copyfd1(MDB_env *env, HANDLE fd)
 		return rc;
 
 	mp = (MDB_page *)my.mc_wbuf[0];
-	memset(mp, 0, NUM_METAS * env->me_psize);
+	memset(mp, 0, 2*env->me_psize);
 	mp->mp_pgno = 0;
 	mp->mp_flags = P_META;
 	mm = (MDB_meta *)METADATA(mp);
@@ -9109,27 +8752,27 @@ mdb_env_copyfd1(MDB_env *env, HANDLE fd)
 		mdb_cursor_init(&mc, txn, FREE_DBI, NULL);
 		while ((rc = mdb_cursor_get(&mc, &key, &data, MDB_NEXT)) == 0)
 			freecount += *(MDB_ID *)data.mv_data;
-		freecount += txn->mt_dbs[FREE_DBI].md_branch_pages +
-			txn->mt_dbs[FREE_DBI].md_leaf_pages +
-			txn->mt_dbs[FREE_DBI].md_overflow_pages;
+		freecount += txn->mt_dbs[0].md_branch_pages +
+			txn->mt_dbs[0].md_leaf_pages +
+			txn->mt_dbs[0].md_overflow_pages;
 
 		/* Set metapage 1 */
 		mm->mm_last_pg = txn->mt_next_pgno - freecount - 1;
-		mm->mm_dbs[MAIN_DBI] = txn->mt_dbs[MAIN_DBI];
-		if (mm->mm_last_pg > NUM_METAS-1) {
-			mm->mm_dbs[MAIN_DBI].md_root = mm->mm_last_pg;
+		mm->mm_dbs[1] = txn->mt_dbs[1];
+		if (mm->mm_last_pg > 1) {
+			mm->mm_dbs[1].md_root = mm->mm_last_pg;
 			mm->mm_txnid = 1;
 		} else {
-			mm->mm_dbs[MAIN_DBI].md_root = P_INVALID;
+			mm->mm_dbs[1].md_root = P_INVALID;
 		}
 	}
-	my.mc_wlen[0] = env->me_psize * NUM_METAS;
+	my.mc_wlen[0] = env->me_psize * 2;
 	my.mc_txn = txn;
 	pthread_mutex_lock(&my.mc_mutex);
 	while(my.mc_new)
 		pthread_cond_wait(&my.mc_cond, &my.mc_mutex);
 	pthread_mutex_unlock(&my.mc_mutex);
-	rc = mdb_env_cwalk(&my, &txn->mt_dbs[MAIN_DBI].md_root, 0);
+	rc = mdb_env_cwalk(&my, &txn->mt_dbs[1].md_root, 0);
 	if (rc == MDB_SUCCESS && my.mc_wlen[my.mc_toggle])
 		rc = mdb_env_cthr_toggle(&my, 1);
 	mdb_env_cthr_toggle(&my, -1);
@@ -9157,9 +8800,9 @@ static int ESECT
 mdb_env_copyfd0(MDB_env *env, HANDLE fd)
 {
 	MDB_txn *txn = NULL;
-	mdb_mutexref_t wmutex = NULL;
+	mdb_mutex_t *wmutex = NULL;
 	int rc;
-	size_t wsize, w3;
+	size_t wsize;
 	char *ptr;
 #ifdef _WIN32
 	DWORD len, w2;
@@ -9179,10 +8822,10 @@ mdb_env_copyfd0(MDB_env *env, HANDLE fd)
 
 	if (env->me_txns) {
 		/* We must start the actual read txn after blocking writers */
-		mdb_txn_end(txn, MDB_END_RESET_TMP);
+		mdb_txn_reset0(txn, "reset-stage1");
 
 		/* Temporarily block writers until we snapshot the meta pages */
-		wmutex = env->me_wmutex;
+		wmutex = MDB_MUTEX(env, w);
 		if (LOCK_MUTEX(rc, env, wmutex))
 			goto leave;
 
@@ -9193,7 +8836,7 @@ mdb_env_copyfd0(MDB_env *env, HANDLE fd)
 		}
 	}
 
-	wsize = env->me_psize * NUM_METAS;
+	wsize = env->me_psize * 2;
 	ptr = env->me_map;
 	w2 = wsize;
 	while (w2 > 0) {
@@ -9218,15 +8861,15 @@ mdb_env_copyfd0(MDB_env *env, HANDLE fd)
 	if (rc)
 		goto leave;
 
-	w3 = txn->mt_next_pgno * env->me_psize;
+	w2 = txn->mt_next_pgno * env->me_psize;
 	{
 		size_t fsize = 0;
 		if ((rc = mdb_fsize(env->me_fd, &fsize)))
 			goto leave;
-		if (w3 > fsize)
-			w3 = fsize;
+		if (w2 > fsize)
+			w2 = fsize;
 	}
-	wsize = w3 - wsize;
+	wsize = w2 - wsize;
 	while (wsize > 0) {
 		if (wsize > MAX_WRITE)
 			w2 = MAX_WRITE;
@@ -9273,9 +8916,6 @@ mdb_env_copy2(MDB_env *env, const char *path, unsigned int flags)
 	int rc, len;
 	char *lpath;
 	HANDLE newfd = INVALID_HANDLE_VALUE;
-#ifdef _WIN32
-	wchar_t *wpath;
-#endif
 
 	if (env->me_flags & MDB_NOSUBDIR) {
 		lpath = (char *)path;
@@ -9293,12 +8933,8 @@ mdb_env_copy2(MDB_env *env, const char *path, unsigned int flags)
 	 * already in the OS cache.
 	 */
 #ifdef _WIN32
-	rc = utf8_to_utf16(lpath, -1, &wpath, NULL);
-	if (rc)
-		goto leave;
-	newfd = CreateFileW(wpath, GENERIC_WRITE, 0, NULL, CREATE_NEW,
+	newfd = CreateFileA(lpath, GENERIC_WRITE, 0, NULL, CREATE_NEW,
 				FILE_FLAG_NO_BUFFERING|FILE_FLAG_WRITE_THROUGH, NULL);
-	free(wpath);
 #else
 	newfd = open(lpath, O_WRONLY|O_CREAT|O_EXCL, 0666);
 #endif
@@ -9343,7 +8979,7 @@ mdb_env_copy(MDB_env *env, const char *path)
 int ESECT
 mdb_env_set_flags(MDB_env *env, unsigned int flag, int onoff)
 {
-	if (flag & ~CHANGEABLE)
+	if (flag & (env->me_map ? ~CHANGEABLE : ~(CHANGEABLE|CHANGELESS)))
 		return EINVAL;
 	if (onoff)
 		env->me_flags |= flag;
@@ -9358,7 +8994,7 @@ mdb_env_get_flags(MDB_env *env, unsigned int *arg)
 	if (!env || !arg)
 		return EINVAL;
 
-	*arg = env->me_flags & (CHANGEABLE|CHANGELESS);
+	*arg = env->me_flags;
 	return MDB_SUCCESS;
 }
 
@@ -9430,32 +9066,36 @@ mdb_stat0(MDB_env *env, MDB_db *db, MDB_stat *arg)
 int ESECT
 mdb_env_stat(MDB_env *env, MDB_stat *arg)
 {
-	MDB_meta *meta;
+	int toggle;
 
 	if (env == NULL || arg == NULL)
 		return EINVAL;
 
-	meta = mdb_env_pick_meta(env);
+	toggle = mdb_env_pick_meta(env);
 
-	return mdb_stat0(env, &meta->mm_dbs[MAIN_DBI], arg);
+	return mdb_stat0(env, &env->me_metas[toggle]->mm_dbs[MAIN_DBI], arg);
 }
 
 int ESECT
 mdb_env_info(MDB_env *env, MDB_envinfo *arg)
 {
-	MDB_meta *meta;
+	int toggle;
 
 	if (env == NULL || arg == NULL)
 		return EINVAL;
 
-	meta = mdb_env_pick_meta(env);
-	arg->me_mapaddr = meta->mm_address;
-	arg->me_last_pgno = meta->mm_last_pg;
-	arg->me_last_txnid = meta->mm_txnid;
-
+	toggle = mdb_env_pick_meta(env);
+	arg->me_mapaddr = env->me_metas[toggle]->mm_address;
 	arg->me_mapsize = env->me_mapsize;
 	arg->me_maxreaders = env->me_maxreaders;
-	arg->me_numreaders = env->me_txns ? env->me_txns->mti_numreaders : 0;
+
+	/* me_numreaders may be zero if this process never used any readers. Use
+	 * the shared numreader count if it exists.
+	 */
+	arg->me_numreaders = env->me_txns ? env->me_txns->mti_numreaders : env->me_numreaders;
+
+	arg->me_last_pgno = env->me_metas[toggle]->mm_last_pg;
+	arg->me_last_txnid = env->me_metas[toggle]->mm_txnid;
 	return MDB_SUCCESS;
 }
 
@@ -9490,12 +9130,15 @@ int mdb_dbi_open(MDB_txn *txn, const char *name, unsigned int flags, MDB_dbi *db
 	MDB_db dummy;
 	int rc, dbflag, exact;
 	unsigned int unused = 0, seq;
-	char *namedup;
 	size_t len;
 
-	if (flags & ~VALID_FLAGS)
+	if (txn->mt_dbxs[FREE_DBI].md_cmp == NULL) {
+		mdb_default_cmp(txn, FREE_DBI);
+	}
+
+	if ((flags & VALID_FLAGS) != flags)
 		return EINVAL;
-	if (txn->mt_flags & MDB_TXN_BLOCKED)
+	if (txn->mt_flags & MDB_TXN_ERROR)
 		return MDB_BAD_TXN;
 
 	/* main DB? */
@@ -9519,7 +9162,7 @@ int mdb_dbi_open(MDB_txn *txn, const char *name, unsigned int flags, MDB_dbi *db
 
 	/* Is the DB already open? */
 	len = strlen(name);
-	for (i=CORE_DBS; i<txn->mt_numdbs; i++) {
+	for (i=2; i<txn->mt_numdbs; i++) {
 		if (!txn->mt_dbxs[i].md_name.mv_size) {
 			/* Remember this free slot */
 			if (!unused) unused = i;
@@ -9541,7 +9184,7 @@ int mdb_dbi_open(MDB_txn *txn, const char *name, unsigned int flags, MDB_dbi *db
 		return (flags & MDB_CREATE) ? MDB_INCOMPATIBLE : MDB_NOTFOUND;
 
 	/* Find the DB info */
-	dbflag = DB_NEW|DB_VALID|DB_USRVALID;
+	dbflag = DB_NEW|DB_VALID;
 	exact = 0;
 	key.mv_size = len;
 	key.mv_data = (void *)name;
@@ -9550,18 +9193,10 @@ int mdb_dbi_open(MDB_txn *txn, const char *name, unsigned int flags, MDB_dbi *db
 	if (rc == MDB_SUCCESS) {
 		/* make sure this is actually a DB */
 		MDB_node *node = NODEPTR(mc.mc_pg[mc.mc_top], mc.mc_ki[mc.mc_top]);
-		if ((node->mn_flags & (F_DUPDATA|F_SUBDATA)) != F_SUBDATA)
+		if (!(node->mn_flags & F_SUBDATA))
 			return MDB_INCOMPATIBLE;
-	} else if (! (rc == MDB_NOTFOUND && (flags & MDB_CREATE))) {
-		return rc;
-	}
-
-	/* Done here so we cannot fail after creating a new DB */
-	if ((namedup = strdup(name)) == NULL)
-		return ENOMEM;
-
-	if (rc) {
-		/* MDB_NOTFOUND and MDB_CREATE: Create new DB */
+	} else if (rc == MDB_NOTFOUND && (flags & MDB_CREATE)) {
+		/* Create if requested */
 		data.mv_size = sizeof(MDB_db);
 		data.mv_data = &dummy;
 		memset(&dummy, 0, sizeof(dummy));
@@ -9571,12 +9206,10 @@ int mdb_dbi_open(MDB_txn *txn, const char *name, unsigned int flags, MDB_dbi *db
 		dbflag |= DB_DIRTY;
 	}
 
-	if (rc) {
-		free(namedup);
-	} else {
-		/* Got info, register DBI in this txn */
+	/* OK, got info, add to table */
+	if (rc == MDB_SUCCESS) {
 		unsigned int slot = unused ? unused : txn->mt_numdbs;
-		txn->mt_dbxs[slot].md_name.mv_data = namedup;
+		txn->mt_dbxs[slot].md_name.mv_data = strdup(name);
 		txn->mt_dbxs[slot].md_name.mv_size = len;
 		txn->mt_dbxs[slot].md_rel = NULL;
 		txn->mt_dbflags[slot] = dbflag;
@@ -9597,13 +9230,12 @@ int mdb_dbi_open(MDB_txn *txn, const char *name, unsigned int flags, MDB_dbi *db
 	return rc;
 }
 
-int ESECT
-mdb_stat(MDB_txn *txn, MDB_dbi dbi, MDB_stat *arg)
+int mdb_stat(MDB_txn *txn, MDB_dbi dbi, MDB_stat *arg)
 {
-	if (!arg || !TXN_DBI_EXIST(txn, dbi, DB_VALID))
+	if (!arg || !TXN_DBI_EXIST(txn, dbi))
 		return EINVAL;
 
-	if (txn->mt_flags & MDB_TXN_BLOCKED)
+	if (txn->mt_flags & MDB_TXN_ERROR)
 		return MDB_BAD_TXN;
 
 	if (txn->mt_dbflags[dbi] & DB_STALE) {
@@ -9618,7 +9250,7 @@ mdb_stat(MDB_txn *txn, MDB_dbi dbi, MDB_stat *arg)
 void mdb_dbi_close(MDB_env *env, MDB_dbi dbi)
 {
 	char *ptr;
-	if (dbi < CORE_DBS || dbi >= env->me_maxdbs)
+	if (dbi <= MAIN_DBI || dbi >= env->me_maxdbs)
 		return;
 	ptr = env->me_dbxs[dbi].md_name.mv_data;
 	/* If there was no name, this was already closed */
@@ -9634,7 +9266,7 @@ void mdb_dbi_close(MDB_env *env, MDB_dbi dbi)
 int mdb_dbi_flags(MDB_txn *txn, MDB_dbi dbi, unsigned int *flags)
 {
 	/* We could return the flags for the FREE_DBI too but what's the point? */
-	if (!TXN_DBI_EXIST(txn, dbi, DB_USRVALID))
+	if (dbi == FREE_DBI || !TXN_DBI_EXIST(txn, dbi))
 		return EINVAL;
 	*flags = txn->mt_dbs[dbi].md_flags & PERSISTENT_FLAGS;
 	return MDB_SUCCESS;
@@ -9657,10 +9289,8 @@ mdb_drop0(MDB_cursor *mc, int subs)
 		MDB_cursor mx;
 		unsigned int i;
 
-		/* DUPSORT sub-DBs have no ovpages/DBs. Omit scanning leaves.
-		 * This also avoids any P_LEAF2 pages, which have no nodes.
-		 */
-		if (mc->mc_flags & C_SUB)
+		/* LEAF2 pages have no nodes, cannot have sub-DBs */
+		if (IS_LEAF2(mc->mc_pg[mc->mc_top]))
 			mdb_cursor_pop(mc);
 
 		mdb_cursor_copy(mc, &mx);
@@ -9726,7 +9356,6 @@ done:
 	} else if (rc == MDB_NOTFOUND) {
 		rc = MDB_SUCCESS;
 	}
-	mc->mc_flags &= ~C_INITIALIZED;
 	return rc;
 }
 
@@ -9735,13 +9364,13 @@ int mdb_drop(MDB_txn *txn, MDB_dbi dbi, int del)
 	MDB_cursor *mc, *m2;
 	int rc;
 
-	if ((unsigned)del > 1 || !TXN_DBI_EXIST(txn, dbi, DB_USRVALID))
+	if ((unsigned)del > 1 || dbi == FREE_DBI || !TXN_DBI_EXIST(txn, dbi))
 		return EINVAL;
 
 	if (F_ISSET(txn->mt_flags, MDB_TXN_RDONLY))
 		return EACCES;
 
-	if (TXN_DBI_CHANGED(txn, dbi))
+	if (dbi > MAIN_DBI && TXN_DBI_CHANGED(txn, dbi))
 		return MDB_BAD_DBI;
 
 	rc = mdb_cursor_open(txn, dbi, &mc);
@@ -9756,8 +9385,8 @@ int mdb_drop(MDB_txn *txn, MDB_dbi dbi, int del)
 		goto leave;
 
 	/* Can't delete the main DB */
-	if (del && dbi >= CORE_DBS) {
-		rc = mdb_del0(txn, MAIN_DBI, &mc->mc_dbx->md_name, NULL, F_SUBDATA);
+	if (del && dbi > MAIN_DBI) {
+		rc = mdb_del0(txn, MAIN_DBI, &mc->mc_dbx->md_name, NULL, 0);
 		if (!rc) {
 			txn->mt_dbflags[dbi] = DB_STALE;
 			mdb_dbi_close(txn->mt_env, dbi);
@@ -9783,7 +9412,7 @@ leave:
 
 int mdb_set_compare(MDB_txn *txn, MDB_dbi dbi, MDB_cmp_func *cmp)
 {
-	if (!TXN_DBI_EXIST(txn, dbi, DB_USRVALID))
+	if (dbi == FREE_DBI || !TXN_DBI_EXIST(txn, dbi))
 		return EINVAL;
 
 	txn->mt_dbxs[dbi].md_cmp = cmp;
@@ -9792,7 +9421,7 @@ int mdb_set_compare(MDB_txn *txn, MDB_dbi dbi, MDB_cmp_func *cmp)
 
 int mdb_set_dupsort(MDB_txn *txn, MDB_dbi dbi, MDB_cmp_func *cmp)
 {
-	if (!TXN_DBI_EXIST(txn, dbi, DB_USRVALID))
+	if (dbi == FREE_DBI || !TXN_DBI_EXIST(txn, dbi))
 		return EINVAL;
 
 	txn->mt_dbxs[dbi].md_dcmp = cmp;
@@ -9801,7 +9430,7 @@ int mdb_set_dupsort(MDB_txn *txn, MDB_dbi dbi, MDB_cmp_func *cmp)
 
 int mdb_set_relfunc(MDB_txn *txn, MDB_dbi dbi, MDB_rel_func *rel)
 {
-	if (!TXN_DBI_EXIST(txn, dbi, DB_USRVALID))
+	if (dbi == FREE_DBI || !TXN_DBI_EXIST(txn, dbi))
 		return EINVAL;
 
 	txn->mt_dbxs[dbi].md_rel = rel;
@@ -9810,7 +9439,7 @@ int mdb_set_relfunc(MDB_txn *txn, MDB_dbi dbi, MDB_rel_func *rel)
 
 int mdb_set_relctx(MDB_txn *txn, MDB_dbi dbi, void *ctx)
 {
-	if (!TXN_DBI_EXIST(txn, dbi, DB_USRVALID))
+	if (dbi == FREE_DBI || !TXN_DBI_EXIST(txn, dbi))
 		return EINVAL;
 
 	txn->mt_dbxs[dbi].md_relctx = ctx;
@@ -9912,10 +9541,9 @@ mdb_reader_check(MDB_env *env, int *dead)
 }
 
 /** As #mdb_reader_check(). rlocked = <caller locked the reader mutex>. */
-static int ESECT
-mdb_reader_check0(MDB_env *env, int rlocked, int *dead)
+static int mdb_reader_check0(MDB_env *env, int rlocked, int *dead)
 {
-	mdb_mutexref_t rmutex = rlocked ? NULL : env->me_rmutex;
+	mdb_mutex_t *rmutex = rlocked ? NULL : MDB_MUTEX(env, r);
 	unsigned int i, j, rdrs;
 	MDB_reader *mr;
 	MDB_PID_T *pids, pid;
@@ -9966,28 +9594,29 @@ mdb_reader_check0(MDB_env *env, int rlocked, int *dead)
 
 #ifdef MDB_ROBUST_SUPPORTED
 /** Handle #LOCK_MUTEX0() failure.
- * Try to repair the lock file if the mutex owner died.
+ * With #MDB_ROBUST, try to repair the lock file if the mutex owner died.
  * @param[in] env	the environment handle
  * @param[in] mutex	LOCK_MUTEX0() mutex
  * @param[in] rc	LOCK_MUTEX0() error (nonzero)
  * @return 0 on success with the mutex locked, or an error code on failure.
  */
-static int ESECT
-mdb_mutex_failed(MDB_env *env, mdb_mutexref_t mutex, int rc)
+static int mdb_mutex_failed(MDB_env *env, mdb_mutex_t *mutex, int rc)
 {
-	int rlocked, rc2;
-	MDB_meta *meta;
+	int toggle, rlocked, rc2;
+#ifndef _WIN32
+	enum { WAIT_ABANDONED = EOWNERDEAD };
+#endif
 
-	if (rc == MDB_OWNERDEAD) {
+	if (rc == (int) WAIT_ABANDONED) {
 		/* We own the mutex. Clean up after dead previous owner. */
 		rc = MDB_SUCCESS;
-		rlocked = (mutex == env->me_rmutex);
+		rlocked = (mutex == MDB_MUTEX(env, r));
 		if (!rlocked) {
 			/* Keep mti_txnid updated, otherwise next writer can
 			 * overwrite data which latest meta page refers to.
 			 */
-			meta = mdb_env_pick_meta(env);
-			env->me_txns->mti_txnid = meta->mm_txnid;
+			toggle = mdb_env_pick_meta(env);
+			env->me_txns->mti_txnid = env->me_metas[toggle]->mm_txnid;
 			/* env is hosed if the dead thread was ours */
 			if (env->me_txn) {
 				env->me_flags |= MDB_FATAL_ERROR;
@@ -9999,7 +9628,7 @@ mdb_mutex_failed(MDB_env *env, mdb_mutexref_t mutex, int rc)
 			(rc ? "this process' env is hosed" : "recovering")));
 		rc2 = mdb_reader_check0(env, rlocked, NULL);
 		if (rc2 == 0)
-			rc2 = mdb_mutex_consistent(mutex);
+			rc2 = pthread_mutex_consistent(mutex);
 		if (rc || (rc = rc2)) {
 			DPRINTF(("LOCK_MUTEX recovery failed, %s", mdb_strerror(rc)));
 			UNLOCK_MUTEX(mutex);
@@ -10015,24 +9644,3 @@ mdb_mutex_failed(MDB_env *env, mdb_mutexref_t mutex, int rc)
 }
 #endif	/* MDB_ROBUST_SUPPORTED */
 /** @} */
-
-#if defined(_WIN32)
-static int utf8_to_utf16(const char *src, int srcsize, wchar_t **dst, int *dstsize)
-{
-	int need;
-	wchar_t *result;
-	need = MultiByteToWideChar(CP_UTF8, 0, src, srcsize, NULL, 0);
-	if (need == 0xFFFD)
-		return EILSEQ;
-	if (need == 0)
-		return EINVAL;
-	result = malloc(sizeof(wchar_t) * need);
-	if (!result)
-		return ENOMEM;
-	MultiByteToWideChar(CP_UTF8, 0, src, srcsize, result, need);
-	if (dstsize)
-		*dstsize = need;
-	*dst = result;
-	return 0;
-}
-#endif /* defined(_WIN32) */
diff --git a/plugins/Dbx_mdb/src/lmdb/midl.c b/plugins/Dbx_mdb/src/lmdb/midl.c
index 5c6d841a7a..88a3aff10c 100644
--- a/plugins/Dbx_mdb/src/lmdb/midl.c
+++ b/plugins/Dbx_mdb/src/lmdb/midl.c
@@ -3,7 +3,7 @@
 /* $OpenLDAP$ */
 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
  *
- * Copyright 2000-2015 The OpenLDAP Foundation.
+ * Copyright 2000-2014 The OpenLDAP Foundation.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -116,15 +116,17 @@ void mdb_midl_free(MDB_IDL ids)
 		free(ids-1);
 }
 
-void mdb_midl_shrink( MDB_IDL *idp )
+int mdb_midl_shrink( MDB_IDL *idp )
 {
 	MDB_IDL ids = *idp;
 	if (*(--ids) > MDB_IDL_UM_MAX &&
-		(ids = realloc(ids, (MDB_IDL_UM_MAX+2) * sizeof(MDB_ID))))
+		(ids = realloc(ids, (MDB_IDL_UM_MAX+1) * sizeof(MDB_ID))))
 	{
 		*ids++ = MDB_IDL_UM_MAX;
 		*idp = ids;
+		return 1;
 	}
+	return 0;
 }
 
 static int mdb_midl_grow( MDB_IDL *idp, int num )
diff --git a/plugins/Dbx_mdb/src/lmdb/midl.h b/plugins/Dbx_mdb/src/lmdb/midl.h
index 2331e78398..3d0e774406 100644
--- a/plugins/Dbx_mdb/src/lmdb/midl.h
+++ b/plugins/Dbx_mdb/src/lmdb/midl.h
@@ -11,7 +11,7 @@
 /* $OpenLDAP$ */
 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
  *
- * Copyright 2000-2015 The OpenLDAP Foundation.
+ * Copyright 2000-2014 The OpenLDAP Foundation.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -27,6 +27,7 @@
 #define _MDB_MIDL_H_
 
 #include <stddef.h>
+#include <stdint.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -42,7 +43,7 @@ extern "C" {
 	/** A generic unsigned ID number. These were entryIDs in back-bdb.
 	 *	Preferably it should have the same size as a pointer.
 	 */
-typedef size_t MDB_ID;
+typedef uint64_t MDB_ID;
 
 	/** An IDL is an ID List, a sorted array of IDs. The first
 	 * element of the array is a counter for how many actual
@@ -98,8 +99,9 @@ void mdb_midl_free(MDB_IDL ids);
 	/** Shrink an IDL.
 	 * Return the IDL to the default size if it has grown larger.
 	 * @param[in,out] idp	Address of the IDL to shrink.
+	 * @return	0 on no change, non-zero if shrunk.
 	 */
-void mdb_midl_shrink(MDB_IDL *idp);
+int mdb_midl_shrink(MDB_IDL *idp);
 
 	/** Make room for num additional elements in an IDL.
 	 * @param[in,out] idp	Address of the IDL.