diff --git a/manifest b/manifest
index cde71db315..4f22c2b67d 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Replace\ssqlite3_memdb_config()\swith\ssqlite3_deserialize().\s\sRemove\sthe\n"db\smemdb"\scommand\sfrom\sthe\sTCL\sinterface,\sreplacing\sit\swith\s"db\sserialize"\nand\s"db\sdeserialize".
-D 2018-01-03T19:03:31.558
+C Miscellaneous\scode\sand\scomment\scleanup.
+D 2018-01-03T22:48:38.759
 F Makefile.in 892bf253c48f3d2d8d4e4e89b44b71aa548a0eba11b148c338690cfb99822859
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 3b7ee2ebaf579fe7d30bece93e61e52782c3ff836455cba3a192f7a8f6f269d6
@@ -415,7 +415,7 @@ F sqlite3.1 fc7ad8990fc8409983309bb80de8c811a7506786
 F sqlite3.pc.in 48fed132e7cb71ab676105d2a4dc77127d8c1f3a
 F src/alter.c cf7a8af45cb0ace672f47a1b29ab24092a9e8cd8d945a9974e3b5d925f548594
 F src/analyze.c 0d0ccf7520a201d8747ea2f02c92c26e26f801bc161f714f27b9f7630dde0421
-F src/attach.c 52c34c2fb1a8852739aca3c4ae797f02660d826d1e79c067dadac97fe3335b6c
+F src/attach.c af582a55cdb0435dc21da926cfcd5545eadfd99ea201b5b9e067cbeae1077077
 F src/auth.c 6277d63837357549fe14e723490d6dc1a38768d71c795c5eb5c0f8a99f918f73
 F src/backup.c faf17e60b43233c214aae6a8179d24503a61e83b
 F src/bitvec.c 17ea48eff8ba979f1f5b04cc484c7bb2be632f33
@@ -450,7 +450,7 @@ F src/mem1.c c12a42539b1ba105e3707d0e628ad70e611040d8f5e38cf942cee30c867083de
 F src/mem2.c f1940d9e91948dd6a908fbb9ce3835c36b5d83c3
 F src/mem3.c 8768ac94694f31ffaf8b4d0ea5dc08af7010a35a
 F src/mem5.c 9bf955937b07f8c32541c8a9991f33ce3173d944
-F src/memdb.c 67c01e51b9e515721fbb4a27375233c67a8a8e5d66bd3fa6f4f84c85de43c05e
+F src/memdb.c d58bb51e6029a7bd91b2148b98ab00c3a271c6cd2632eb756cfcd91e1252930b
 F src/memjournal.c 6f3d36a0a8f72f48f6c3c722f04301ac64f2515435fa42924293e46fc7994661
 F src/msvc.h 4942752b6a253116baaa8de75256c51a459a5e81
 F src/mutex.c b021263554c8a3995e9d53193b8194b96d1ed28e06c3b532dd7f7d29cf0c7d53
@@ -1690,7 +1690,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 8cf2ed4eff6d2e0958656e23384b05ead2128b678b0b69a591878af4190cd077
-R 752064346b8d3ad9381bcf73633be499
+P 2f6e9df9f0c5a9e5b1acb99cfa9486850cc1822d35b0989e779a7a10f3b1f1ac
+R bb0359f4210b8aee0e32802f6ef52a4c
 U drh
-Z 59a3fb5e3f8eae3c5ea078db9efbd371
+Z c49fae41835e3bd8d0d8eeb0cf1f4a88
diff --git a/manifest.uuid b/manifest.uuid
index 08b82513bb..cf39388ce7 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-2f6e9df9f0c5a9e5b1acb99cfa9486850cc1822d35b0989e779a7a10f3b1f1ac
\ No newline at end of file
+fa6069fb3b0a4411fd6661dec7de40ece3064a2fe4b94ebfbda9e5e524e04e86
\ No newline at end of file
diff --git a/src/attach.c b/src/attach.c
index 151b52e7a4..f177f1a5b5 100644
--- a/src/attach.c
+++ b/src/attach.c
@@ -84,7 +84,13 @@ static void attachFunc(
   if( zFile==0 ) zFile = "";
   if( zName==0 ) zName = "";
 
-  if( db->init.reopenMemdb ){
+#ifdef SQLITE_ENABLE_MEMDB
+# define REOPEN_AS_MEMDB(db)  (db->init.reopenMemdb)
+#else
+# define REOPEN_AS_MEMDB(db)  (0)
+#endif
+
+  if( REOPEN_AS_MEMDB(db) ){
     /* This is not a real ATTACH.  Instead, this routine is being called
     ** from sqlite3_deserialize() to close database db->init.iDb and
     ** reopen it as a MemDB */
@@ -96,9 +102,9 @@ static void attachFunc(
     pNew->pSchema = 0;
     rc = sqlite3BtreeOpen(pVfs, "x", db, &pNew->pBt, 0, SQLITE_OPEN_MAIN_DB);
   }else{
-    /* This is a real ATTACH */
-  
-    /* Check for the following errors:
+    /* This is a real ATTACH
+    **
+    ** Check for the following errors:
     **
     **     * Too many attached databases,
     **     * Transaction currently open
@@ -178,7 +184,7 @@ static void attachFunc(
     sqlite3BtreeLeave(pNew->pBt);
   }
   pNew->safety_level = SQLITE_DEFAULT_SYNCHRONOUS+1;
-  if( !db->init.reopenMemdb ) pNew->zDbSName = sqlite3DbStrDup(db, zName);
+  if( !REOPEN_AS_MEMDB(db) ) pNew->zDbSName = sqlite3DbStrDup(db, zName);
   if( rc==SQLITE_OK && pNew->zDbSName==0 ){
     rc = SQLITE_NOMEM_BKPT;
   }
@@ -235,7 +241,7 @@ static void attachFunc(
     }
   }
 #endif
-  if( rc ){
+  if( rc && !REOPEN_AS_MEMDB(db) ){
     int iDb = db->nDb - 1;
     assert( iDb>=2 );
     if( db->aDb[iDb].pBt ){
diff --git a/src/memdb.c b/src/memdb.c
index 5a1f12dcbb..5aa66f1fde 100644
--- a/src/memdb.c
+++ b/src/memdb.c
@@ -10,8 +10,11 @@
 **
 ******************************************************************************
 **
-** This is an in-memory VFS implementation.  The application supplies
-** a chunk of memory to hold the database file.
+** This file implements in-memory VFS.  A database is held as a contiguous
+** block of memory.
+**
+** This file also implements interface sqlite3_serialize() and
+** sqlite3_deserialize().
 */
 #ifdef SQLITE_ENABLE_MEMDB
 #include "sqliteInt.h"
@@ -52,10 +55,6 @@ static int memdbCheckReservedLock(sqlite3_file*, int *pResOut);
 static int memdbFileControl(sqlite3_file*, int op, void *pArg);
 static int memdbSectorSize(sqlite3_file*);
 static int memdbDeviceCharacteristics(sqlite3_file*);
-static int memdbShmMap(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
-static int memdbShmLock(sqlite3_file*, int offset, int n, int flags);
-static void memdbShmBarrier(sqlite3_file*);
-static int memdbShmUnmap(sqlite3_file*, int deleteFlag);
 static int memdbFetch(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
 static int memdbUnfetch(sqlite3_file*, sqlite3_int64 iOfst, void *p);
 
@@ -112,10 +111,10 @@ static const sqlite3_io_methods memdb_io_methods = {
   memdbFileControl,                /* xFileControl */
   memdbSectorSize,                 /* xSectorSize */
   memdbDeviceCharacteristics,      /* xDeviceCharacteristics */
-  memdbShmMap,                     /* xShmMap */
-  memdbShmLock,                    /* xShmLock */
-  memdbShmBarrier,                 /* xShmBarrier */
-  memdbShmUnmap,                   /* xShmUnmap */
+  0,                               /* xShmMap */
+  0,                               /* xShmLock */
+  0,                               /* xShmBarrier */
+  0,                               /* xShmUnmap */
   memdbFetch,                      /* xFetch */
   memdbUnfetch                     /* xUnfetch */
 };
@@ -264,32 +263,6 @@ static int memdbDeviceCharacteristics(sqlite3_file *pFile){
          SQLITE_IOCAP_SEQUENTIAL;
 }
 
-/* Create a shared memory file mapping */
-static int memdbShmMap(
-  sqlite3_file *pFile,
-  int iPg,
-  int pgsz,
-  int bExtend,
-  void volatile **pp
-){
-  return SQLITE_IOERR_SHMMAP;
-}
-
-/* Perform locking on a shared-memory segment */
-static int memdbShmLock(sqlite3_file *pFile, int offset, int n, int flags){
-  return SQLITE_IOERR_SHMLOCK;
-}
-
-/* Memory barrier operation on shared memory */
-static void memdbShmBarrier(sqlite3_file *pFile){
-  return;
-}
-
-/* Unmap a shared memory segment */
-static int memdbShmUnmap(sqlite3_file *pFile, int deleteFlag){
-  return SQLITE_OK;
-}
-
 /* Fetch a page of a memory-mapped file */
 static int memdbFetch(
   sqlite3_file *pFile,