diff --git a/Makefile.linux-gcc b/Makefile.linux-gcc
index ad5d4dd093..fe7349ad46 100644
--- a/Makefile.linux-gcc
+++ b/Makefile.linux-gcc
@@ -22,12 +22,6 @@ TOP = ../sqlite
 BCC = gcc -g -O0
 #BCC = /opt/ancic/bin/c89 -0
 
-#### If the target operating system supports the "usleep()" system
-#    call, then define the HAVE_USLEEP macro for all C modules.
-#
-#USLEEP = 
-USLEEP = -DHAVE_USLEEP=1
-
 #### If you want the SQLite library to be safe for use within a 
 #    multi-threaded program, then define the following macro
 #    appropriately:
diff --git a/ext/fts5/fts5_index.c b/ext/fts5/fts5_index.c
index e46840c2e8..9d80e79e56 100644
--- a/ext/fts5/fts5_index.c
+++ b/ext/fts5/fts5_index.c
@@ -4752,7 +4752,7 @@ static int fts5IndexFindDeleteMerge(Fts5Index *p, Fts5Structure *pStruct){
         nEntry += pLvl->aSeg[iSeg].nEntry;
         nTomb += pLvl->aSeg[iSeg].nEntryTombstone;
       }
-      assert( nEntry>0 || pLvl->nSeg==0 );
+      assert_nc( nEntry>0 || pLvl->nSeg==0 );
       if( nEntry>0 ){
         int nPercent = (nTomb * 100) / nEntry;
         if( nPercent>=pConfig->nDeleteMerge && nPercent>nBest ){
@@ -8092,15 +8092,16 @@ static int fts5structCloseMethod(sqlite3_vtab_cursor *cur){
 */
 static int fts5structNextMethod(sqlite3_vtab_cursor *cur){
   Fts5StructVcsr *pCsr = (Fts5StructVcsr*)cur;
+  Fts5Structure *p = pCsr->pStruct;
 
   assert( pCsr->pStruct );
   pCsr->iSeg++;
   pCsr->iRowid++;
-  while( pCsr->iSeg>=pCsr->pStruct->aLevel[pCsr->iLevel].nSeg ){
+  while( pCsr->iLevel<p->nLevel && pCsr->iSeg>=p->aLevel[pCsr->iLevel].nSeg ){
     pCsr->iLevel++;
     pCsr->iSeg = 0;
   }
-  if( pCsr->iLevel>=pCsr->pStruct->nLevel ){
+  if( pCsr->iLevel>=p->nLevel ){
     fts5StructureRelease(pCsr->pStruct);
     pCsr->pStruct = 0;
   }
diff --git a/ext/wasm/api/extern-post-js.c-pp.js b/ext/wasm/api/extern-post-js.c-pp.js
index 00cb3fab90..63e55051c6 100644
--- a/ext/wasm/api/extern-post-js.c-pp.js
+++ b/ext/wasm/api/extern-post-js.c-pp.js
@@ -62,6 +62,7 @@ const toExportForESM =
   globalThis.sqlite3InitModule = function ff(...args){
     //console.warn("Using replaced sqlite3InitModule()",globalThis.location);
     return originalInit(...args).then((EmscriptenModule)=>{
+//#if wasmfs
       if('undefined'!==typeof WorkerGlobalScope &&
          EmscriptenModule['ENVIRONMENT_IS_PTHREAD']){
         /** Workaround for wasmfs-generated worker, which calls this
@@ -72,6 +73,7 @@ const toExportForESM =
         //console.warn("sqlite3InitModule() returning E-module.",EmscriptenModule);
         return EmscriptenModule;
       }
+//#endif
       //console.warn("sqlite3InitModule() returning sqlite3 object.");
       const s = EmscriptenModule.sqlite3;
       s.scriptInfo = initModuleState;
diff --git a/ext/wasm/api/sqlite3-api-prologue.js b/ext/wasm/api/sqlite3-api-prologue.js
index 0179091c02..3b29041c37 100644
--- a/ext/wasm/api/sqlite3-api-prologue.js
+++ b/ext/wasm/api/sqlite3-api-prologue.js
@@ -1645,7 +1645,8 @@ globalThis.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
          do not.
       */
       tgt.push(capi.sqlite3_value_to_js(
-        wasm.peekPtr(pArgv + (wasm.ptrSizeof * i))
+        wasm.peekPtr(pArgv + (wasm.ptrSizeof * i)),
+        throwIfCannotConvert
       ));
     }
     return tgt;
diff --git a/ext/wasm/api/sqlite3-vfs-opfs-sahpool.c-pp.js b/ext/wasm/api/sqlite3-vfs-opfs-sahpool.c-pp.js
index ee8d1a5d68..3ba889c393 100644
--- a/ext/wasm/api/sqlite3-vfs-opfs-sahpool.c-pp.js
+++ b/ext/wasm/api/sqlite3-vfs-opfs-sahpool.c-pp.js
@@ -865,6 +865,7 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
 
     //! Documented elsewhere in this file.
     importDb(name, bytes){
+      if(bytes instanceof ArrayBuffer) bytes = new Uint8Array(bytes);
       const n = bytes.byteLength;
       if(n<512 || n%512!=0){
         toss("Byte array size is invalid for an SQLite db.");
@@ -1074,16 +1075,17 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
      Returns an array of the names of the files currently allocated to
      slots. This list is the same length as getFileCount().
 
-     - void importDb(name, byteArray)
+     - void importDb(name, bytes)
 
      Imports the contents of an SQLite database, provided as a byte
-     array, under the given name, overwriting any existing
-     content. Throws if the pool has no available file slots, on I/O
-     error, or if the input does not appear to be a database. In the
-     latter case, only a cursory examination is made.  Note that this
-     routine is _only_ for importing database files, not arbitrary files,
-     the reason being that this VFS will automatically clean up any
-     non-database files so importing them is pointless.
+     array or ArrayBuffer, under the given name, overwriting any
+     existing content. Throws if the pool has no available file slots,
+     on I/O error, or if the input does not appear to be a
+     database. In the latter case, only a cursory examination is made.
+     Note that this routine is _only_ for importing database files,
+     not arbitrary files, the reason being that this VFS will
+     automatically clean up any non-database files so importing them
+     is pointless.
 
      - [async] number reduceCapacity(n)
 
diff --git a/ext/wasm/fiddle.make b/ext/wasm/fiddle.make
index cbe6ab3518..57141d7e2b 100644
--- a/ext/wasm/fiddle.make
+++ b/ext/wasm/fiddle.make
@@ -18,7 +18,7 @@ endif
 ifeq (,$(SHELL_SRC))
 $(error Could not parse SHELL_SRC from $(dir.top)/Makefile.)
 endif
-$(dir.top)/shell.c: $(SHELL_SRC) $(dir.top)/tool/mkshellc.tcl
+$(dir.top)/shell.c: $(SHELL_SRC) $(dir.top)/tool/mkshellc.tcl $(sqlite3.c)
 	$(MAKE) -C $(dir.top) shell.c
 # /shell.c
 ########################################################################
@@ -61,9 +61,9 @@ $(fiddle.SOAP.js): $(SOAP.js)
 $(eval $(call call-make-pre-post,fiddle-module,vanilla))
 $(fiddle-module.js): $(MAKEFILE) $(MAKEFILE.fiddle) \
     $(EXPORTED_FUNCTIONS.fiddle) \
-    $(fiddle.cses) $(pre-post-fiddle-module.deps.vanilla) $(fiddle.SOAP.js)
+    $(fiddle.cses) $(pre-post-fiddle-module-vanilla.deps) $(fiddle.SOAP.js)
 	$(emcc.bin) -o $@ $(fiddle.emcc-flags) \
-    $(pre-post-fiddle-module.flags.vanilla) \
+    $(pre-post-fiddle-module-vanilla.flags) \
     $(fiddle.cses)
 	$(maybe-wasm-strip) $(fiddle-module.wasm)
 	gzip < $@ > $@.gz
diff --git a/ext/wasm/fiddle/fiddle-worker.js b/ext/wasm/fiddle/fiddle-worker.js
index e239cbf51e..67f61008fb 100644
--- a/ext/wasm/fiddle/fiddle-worker.js
+++ b/ext/wasm/fiddle/fiddle-worker.js
@@ -221,7 +221,7 @@
       f._();
     }
   };
-  
+
   self.onmessage = function f(ev){
     ev = ev.data;
     if(!f.cache){
@@ -371,12 +371,14 @@
   sqlite3InitModule(fiddleModule).then((_sqlite3)=>{
     sqlite3 = _sqlite3;
     console.warn("Installing sqlite3 module globally (in Worker)",
-                 "for use in the dev console.");
-    self.sqlite3 = sqlite3;
+                 "for use in the dev console.", sqlite3);
+    globalThis.sqlite3 = sqlite3;
     const dbVfs = sqlite3.wasm.xWrap('fiddle_db_vfs', "*", ['string']);
     fiddleModule.fsUnlink = (fn)=>{
       return sqlite3.wasm.sqlite3_wasm_vfs_unlink(dbVfs(0), fn);
     };
     wMsg('fiddle-ready');
-  })/*then()*/;
+  }).catch(e=>{
+    console.error("Fiddle worker init failed:",e);
+  });
 })();
diff --git a/ext/wasm/tester1.c-pp.js b/ext/wasm/tester1.c-pp.js
index db4b50f4b6..c1b16d5e81 100644
--- a/ext/wasm/tester1.c-pp.js
+++ b/ext/wasm/tester1.c-pp.js
@@ -353,7 +353,7 @@ globalThis.sqlite3InitModule = sqlite3InitModule;
   const sahPoolConfig = {
     name: 'opfs-sahpool-tester1',
     clearOnInit: true,
-    initialCapacity: 3
+    initialCapacity: 6
   };
   ////////////////////////////////////////////////////////////////////////
   // End of infrastructure setup. Now define the tests...
@@ -3076,7 +3076,24 @@ globalThis.sqlite3InitModule = sqlite3InitModule;
         T.assert(1 === fileNames.length)
           .assert(dbName === fileNames[0])
           .assert(1 === u1.getFileCount())
-          .assert(true === u1.unlink(dbName))
+
+        if(1){ // test exportFile() and importDb()
+          const dbytes = u1.exportFile(dbName);
+          T.assert(dbytes.length >= 4096);
+          const dbName2 = '/exported.db';
+          u1.importDb(dbName2, dbytes);
+          T.assert( 2 == u1.getFileCount() );
+          let db2 = new u1.OpfsSAHPoolDb(dbName2);
+          T.assert(db2 instanceof sqlite3.oo1.DB)
+            .assert(3 === db2.selectValue('select count(*) from t'));
+          db2.close();
+          T.assert(true === u1.unlink(dbName2))
+            .assert(false === u1.unlink(dbName2))
+            .assert(1 === u1.getFileCount())
+            .assert(1 === u1.getFileNames().length);
+        }
+
+        T.assert(true === u1.unlink(dbName))
           .assert(false === u1.unlink(dbName))
           .assert(0 === u1.getFileCount())
           .assert(0 === u1.getFileNames().length);
@@ -3089,6 +3106,7 @@ globalThis.sqlite3InitModule = sqlite3InitModule;
         log("Installed second SAH instance as",conf2.name);
         T.assert(0 === POther.getFileCount())
           .assert(true === await POther.removeVfs());
+
         if(0){
            /* Enable this block to inspect vfs's contents via the dev
               console or OPFS Explorer browser extension.  The
diff --git a/manifest b/manifest
index fb3b812441..b5e978aaf9 100644
--- a/manifest
+++ b/manifest
@@ -1,10 +1,10 @@
 C Merge\sthe\slatest\strunk\senhancements\sinto\sthe\sbedrock\sbranch.
-D 2023-07-28T18:52:09.247
+D 2023-08-03T23:26:39.123
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
 F Makefile.in 0423d5a97be582884ffdb228216790f5bb10678bed50f359cce6f0745107bf32
-F Makefile.linux-gcc f609543700659711fbd230eced1f01353117621dccae7b9fb70daa64236c5241
+F Makefile.linux-gcc f3842a0b1efbfbb74ac0ef60e56b301836d05b4d867d014f714fa750048f1ab6
 F Makefile.msc 97f9b14ef0418943c315db08f4961932f2fc839603c13ab646079840b0d83329
 F README.md c1c4218efcc4071a6e26db2b517fdbc1035696a29b370edd655faddbef02b224
 F VERSION c6366dc72582d3144ce87b013cc35fe48d62f6d07d5be0c9716ea33c862144aa
@@ -94,7 +94,7 @@ F ext/fts5/fts5_buffer.c 3001fbabb585d6de52947b44b455235072b741038391f830d6b7292
 F ext/fts5/fts5_config.c 054359543566cbff1ba65a188330660a5457299513ac71c53b3a07d934c7b081
 F ext/fts5/fts5_expr.c 2473c13542f463cae4b938c498d6193c90d38ea1a2a4f9849c0479736e50d24d
 F ext/fts5/fts5_hash.c 65e7707bc8774706574346d18c20218facf87de3599b995963c3e6d6809f203d
-F ext/fts5/fts5_index.c a4e35cd126c19df66887801db15ccae7290b51129add3d4cdd31e2d9ea240398
+F ext/fts5/fts5_index.c 93b4cd116b76b6adf224cd3d213f1e06cfe10ae0eb21d6372b1c53b8f0c382a3
 F ext/fts5/fts5_main.c 08a60103dd5bc1b58c5f83f92ec40e2c1d369c8525a943545379e43d18c973a6
 F ext/fts5/fts5_storage.c 3c9b41fce41b6410f2e8f82eb035c6a29b2560483f773e6dc98cf3cb2e4ddbb5
 F ext/fts5/fts5_tcl.c b1445cbe69908c411df8084a10b2485500ac70a9c747cdc8cda175a3da59d8ae
@@ -502,7 +502,7 @@ F ext/wasm/api/EXPORTED_FUNCTIONS.sqlite3-api c5eaceabb9e759aaae7d3101a4a3e542f9
 F ext/wasm/api/EXPORTED_FUNCTIONS.sqlite3-see fb29e62082a658f0d81102488414d422c393c4b20cc2f685b216bc566237957b
 F ext/wasm/api/EXPORTED_RUNTIME_METHODS.sqlite3-api 1ec3c73e7d66e95529c3c64ac3de2470b0e9e7fbf7a5b41261c367cf4f1b7287
 F ext/wasm/api/README.md 5eb44fa02e9c693a1884a3692428647894b0380b24bca120866b7a24c8786134
-F ext/wasm/api/extern-post-js.c-pp.js e7257ea56d4077d0773d7537fcb8eade59aad0c118dab92497c27939edca41cb
+F ext/wasm/api/extern-post-js.c-pp.js c4154a7f90c2d7e51fd6738273908152036c3457fdc0b6523f1be3ef51105aac
 F ext/wasm/api/extern-pre-js.js cc61c09c7a24a07dbecb4c352453c3985170cec12b4e7e7e7a4d11d43c5c8f41
 F ext/wasm/api/post-js-footer.js cd0a8ec768501d9bd45d325ab0442037fb0e33d1f3b4f08902f15c34720ee4a1
 F ext/wasm/api/post-js-header.js 47b6b281f39ad59fa6e8b658308cd98ea292c286a68407b35ff3ed9cfd281a62
@@ -510,12 +510,12 @@ F ext/wasm/api/pre-js.c-pp.js ad906703f7429590f2fbf5e6498513bf727a1a4f0ebfa057af
 F ext/wasm/api/sqlite3-api-cleanup.js d235ad237df6954145404305040991c72ef8b1881715d2a650dda7b3c2576d0e
 F ext/wasm/api/sqlite3-api-glue.js cc6b0bb093bdb6279d4af259200b7b9e150e3796a8a3a4cd09a4928c43d25e56
 F ext/wasm/api/sqlite3-api-oo1.js 9678dc4d9a5d39632b6ffe6ea94a023119260815bf32f265bf5f6c36c9516db8
-F ext/wasm/api/sqlite3-api-prologue.js cbd7d6ba185f3a844a8b0020e954b49bbc2ca78b305d117bec2ceca21431795a
+F ext/wasm/api/sqlite3-api-prologue.js 76258e160bf6a89cc75a7d3c05646a054c8cab7219cd1e10bc20cacaad022131
 F ext/wasm/api/sqlite3-api-worker1.js 9f32af64df1a031071912eea7a201557fe39b1738645c0134562bb84e88e2fec
 F ext/wasm/api/sqlite3-license-version-header.js 0c807a421f0187e778dc1078f10d2994b915123c1223fe752b60afdcd1263f89
 F ext/wasm/api/sqlite3-opfs-async-proxy.js 8cf8a897726f14071fae6be6648125162b256dfb4f96555b865dbb7a6b65e379
 F ext/wasm/api/sqlite3-v-helper.js 7daa0eab0a513a25b05e9abae7b5beaaa39209b3ed12f86aeae9ef8d2719ed25
-F ext/wasm/api/sqlite3-vfs-opfs-sahpool.c-pp.js 44740935f6eeab3a0c6dc9f0ca93aebb6339f8d8365f03ea6d7808c134dbfe46
+F ext/wasm/api/sqlite3-vfs-opfs-sahpool.c-pp.js 54cee22aacadb9dfaea438d72ac0882249d028c37903208d48c52871290ceff7
 F ext/wasm/api/sqlite3-vfs-opfs.c-pp.js e7a690e0e78ff4d563f2eca468f91db69f001ff4b79c6d2304cbb6f62dca437d
 F ext/wasm/api/sqlite3-wasm.c 8867f1d41c112fb4a2cfe22ff224eccaf309fcdea266cee0ec554f85db72ef0f
 F ext/wasm/api/sqlite3-worker1-promiser.c-pp.js f10c3ecd9df06f6320073c2ce230a7ed7c56034d8b88c1e57095f2a97faf423a
@@ -538,9 +538,9 @@ F ext/wasm/demo-worker1.html 2c178c1890a2beb5a5fecb1453e796d067a4b8d3d2a04d65ca2
 F ext/wasm/demo-worker1.js 836bece8615b17b1b572584f7b15912236a5947fe8c68b98d2737d7e287447ef
 F ext/wasm/dist.make 3a851858aad72e246a5d9c5aaf6b6a144305f1bf898ac1846760ea7bab95c9a3
 F ext/wasm/example_extra_init.c 2347cd69d19d839ef4e5e77b7855103a7fe3ef2af86f2e8c95839afd8b05862f
-F ext/wasm/fiddle.make dbe36b90b8907ae28ecb9c0e9fd8389dbdaecf117ea4fb2ea33864bdfa498a94
+F ext/wasm/fiddle.make fa2ba6e90457ba2a71cb745f200d409caf773076df75ae5b177cc225d7627a11
 F ext/wasm/fiddle/emscripten.css 3d253a6fdb8983a2ac983855bfbdd4b6fa1ff267c28d69513dd6ef1f289ada3f
-F ext/wasm/fiddle/fiddle-worker.js 163d6139a93fab4bcb72064923df050d4e7c0ff0d8aa061ce8776a6e75da8a10
+F ext/wasm/fiddle/fiddle-worker.js e0153f9af6500805c6f09c0b3cfdb7d857e9d6863dbee9d50d1628fccf5f4b4d
 F ext/wasm/fiddle/fiddle.html 550c5aafce40bd218de9bf26192749f69f9b10bc379423ecd2e162bcef885c08
 F ext/wasm/fiddle/fiddle.js 974b995119ac443685d7d94d3b3c58c6a36540e9eb3fed7069d5653284071715
 F ext/wasm/index-dist.html 22379774f0ad4edcaaa8cf9c674c82e794cc557719a8addabed74eb8069d412e
@@ -562,7 +562,7 @@ F ext/wasm/test-opfs-vfs.html 1f2d672f3f3fce810dfd48a8d56914aba22e45c6834e262555
 F ext/wasm/test-opfs-vfs.js f09266873e1a34d9bdb6d3981ec8c9e382f31f215c9fd2f9016d2394b8ae9b7b
 F ext/wasm/tester1-worker.html ebc4b820a128963afce328ecf63ab200bd923309eb939f4110510ab449e9814c
 F ext/wasm/tester1.c-pp.html 1c1bc78b858af2019e663b1a31e76657b73dc24bede28ca92fbe917c3a972af2
-F ext/wasm/tester1.c-pp.js b9a493a764f2113f6a8205d4e5573a25731d6f965338005460920389ac0693e0
+F ext/wasm/tester1.c-pp.js b88dcad5424a652e8204c44a71bbc3deb22a4922c97ba792aedbabb7a6827b91
 F ext/wasm/tests/opfs/concurrency/index.html 0802373d57034d51835ff6041cda438c7a982deea6079efd98098d3e42fbcbc1
 F ext/wasm/tests/opfs/concurrency/test.js a98016113eaf71e81ddbf71655aa29b0fed9a8b79a3cdd3620d1658eb1cc9a5d
 F ext/wasm/tests/opfs/concurrency/worker.js 0a8c1a3e6ebb38aabbee24f122693f1fb29d599948915c76906681bb7da1d3d2
@@ -592,7 +592,7 @@ F src/bitvec.c 501daeef838fa82a9fb53540d72f29e3d9172c8867f1e19f94f681e2e20b966e
 F src/btmutex.c 79a43670447eacc651519a429f6ece9fd638563cf95b469d6891185ddae2b522
 F src/btree.c 728b0fa125e113553489389ffb6992ce2e0bda0431a1e9f2f8baac952bd07e01
 F src/btree.h d906e4d53f483c83d471d99479fa73fcdf20696305d578876f46ee283f3507cb
-F src/btreeInt.h c99c2c6b29c1d36f2a6cc67dcf220b080c8817cb2812e6d5ca27e158a14e1e68
+F src/btreeInt.h 9c6d726acb6357b12683908530073836d9eb515bdeda3e32ee998edc3542a750
 F src/build.c d1f3d6478799b6eef9bb39214fc5495c8ee940fe2e70bf0b65ad8b6984bf0db9
 F src/callback.c db3a45e376deff6a16c0058163fe0ae2b73a2945f3f408ca32cf74960b28d490
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
@@ -600,7 +600,7 @@ F src/ctime.c f439c21d439aaf4706950a2597474f1a796b557a0750666308202c0f601ef0fd
 F src/date.c f73f203b3877cef866c60ab402aec2bf89597219b60635cf50cbe3c5e4533e94
 F src/dbpage.c f3eea5f7ec47e09ee7da40f42b25092ecbe961fc59566b8e5f705f34335b2387
 F src/dbstat.c ec92074baa61d883de58c945162d9e666c13cd7cf3a23bc38b4d1c4d0b2c2bef
-F src/delete.c cd5f5cd06ed0b6a882ec1a8c2a0d73b3cecb28479ad19e9931c4706c5e2182be
+F src/delete.c cb766727c78e715f9fb7ec8a7d03658ed2a3016343ca687acfcec9083cdca500
 F src/expr.c ef4a81822da6f767696bd7f4b9983328af061158958138540142285a5b1181b7
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c a7fcbf7e66d14dbb73cf49f31489ebf66d0e6006c62b95246924a3bae9f37b36
@@ -611,10 +611,10 @@ F src/hash.h 3340ab6e1d13e725571d7cee6d3e3135f0779a7d8e76a9ce0a85971fa3953c51
 F src/hwtime.h f9c2dfb84dce7acf95ce6d289e46f5f9d3d1afd328e53da8f8e9008e3b3caae6
 F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
 F src/insert.c 3f0a94082d978bbdd33c38fefea15346c6c6bffb70bc645a71dc0f1f87dd3276
-F src/json.c 60b6b0815ddaf546396e3c7328065a114b581721dc1fa20697a52610fb2259aa
+F src/json.c d2b7f613a1792043f8e758fdcfe9469f9b81f522999b508f436517752a5d7071
 F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
 F src/loadext.c 176d6b2cb18a6ad73b133db17f6fc351c4d9a2d510deebdb76c22bde9cfd1465
-F src/main.c 429a1a25752edd6afa97de4b8ac10b98f557bbd93f01e39fcd2fa2204a8f54bb
+F src/main.c e56843b488ead74369eeffc64cd5b9d3a7ffbf8621bb0cd695272d9b9ce53afa
 F src/malloc.c 47b82c5daad557d9b963e3873e99c22570fb470719082c6658bf64e3012f7d23
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c 3bb59158c38e05f6270e761a9f435bf19827a264c13d1631c58b84bdc96d73b2
@@ -635,7 +635,7 @@ F src/os.h 1ff5ae51d339d0e30d8a9d814f4b8f8e448169304d83a7ed9db66a65732f3e63
 F src/os_common.h 6c0eb8dd40ef3e12fe585a13e709710267a258e2c8dd1c40b1948a1d14582e06
 F src/os_kv.c 4d39e1f1c180b11162c6dc4aa8ad34053873a639bac6baae23272fc03349986a
 F src/os_setup.h 6011ad7af5db4e05155f385eb3a9b4470688de6f65d6166b8956e58a3d872107
-F src/os_unix.c c2c3b93b716194a2115b282c37f828438e071e6f2fc4e38c5d6f24d5ba822e7a
+F src/os_unix.c c8003dfe6502315cf930160b6cf1b93f82211bed5ab9226509faa6324030c8ea
 F src/os_win.c 7038223a1cda0a47e2ab4db47f63bf1833fe53ba0542f0f283a062ea13894103
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
 F src/pager.c 71f3c8b45890d35156518ffeb71e422274557793cbedff80585b4e292feed234
@@ -651,17 +651,17 @@ F src/printf.c e3ba080e2f409f9bfcc8d34724e6fc160e9c718dc92d0548f6b71b8b6f860ce2
 F src/random.c 9bd018738ec450bf35d28050b4b33fa9a6eebf3aaefb1a1cff42dc14a7725673
 F src/resolve.c 37953a5f36c60bea413c3c04efcd433b6177009f508ef2ace0494728912fe2e9
 F src/rowset.c 8432130e6c344b3401a8874c3cb49fefe6873fec593294de077afea2dce5ec97
-F src/select.c 0b7c7b89576c39a5e6c166a12d1f377fd58bd26da16db0a580bbfa74d7b9e140
+F src/select.c 0945ea9f5bb57efda1156b69c3d1f2d41f7fe0ad1cd5f79142fd145791e6f4fd
 F src/shell.c.in 694aaf751f00610381533d4a31c83d142cfc83ef91ef65e2aa6912ace7c39b40
-F src/sqlite.h.in cadea2f657e69e715e4a2e501cd0139c2a613e00ad771957b4bd9cc5a8a628ff
+F src/sqlite.h.in bc5d3d1776a3681ab552590c60589e0e93cbdfb66c7ed1615d649a180a62805f
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h da473ce2b3d0ae407a6300c4a164589b9a6bfdbec9462688a8593ff16f3bb6e4
-F src/sqliteInt.h 3f9fcac18b13d70e3098d2a3e630e8e5a72f528b30cc66a6c5fe50dbbf26d2fe
+F src/sqliteInt.h c6d007de03ed2f9e74cbf31b6ecea0fd7fdd2cf5aa68ca4a0f5ea1df46b09c17
 F src/sqliteLimit.h 33b1c9baba578d34efe7dfdb43193b366111cdf41476b1e82699e14c11ee1fb6
 F src/status.c 160c445d7d28c984a0eae38c144f6419311ed3eace59b44ac6dafc20db4af749
 F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
 F src/tclsqlite.c ecbc3c99c0d0c3ed122a913f143026c26d38d57f33e06bb71185dd5c1efe37cd
-F src/test1.c 60804113ea9fdbd2dff1c711f4c7d7f41eaac3f3bf1dabfdbc997ac1b14d4f38
+F src/test1.c 91addc5c30c1389d257380b6e42ae0681d32d24553b9938d798a47ff96fa75ca
 F src/test2.c 827446e259a3b7ab949da1542953edda7b5117982576d3e6f1c24a0dd20a5cef
 F src/test3.c e5178558c41ff53236ae0271e9acb3d6885a94981d2eb939536ee6474598840e
 F src/test4.c 4533b76419e7feb41b40582554663ed3cd77aaa54e135cf76b3205098cd6e664
@@ -716,18 +716,18 @@ F src/threads.c 4ae07fa022a3dc7c5beb373cf744a85d3c5c6c3c
 F src/tokenize.c 0fb405f9adf3f757c26bfc1ae6d58ac5dccbb918917ba9e5ef0e6673a06563d3
 F src/treeview.c 1d52fbc4e97161e65858d36e3424ea6e3fc045dd8a679c82b4b9593dc30de3bd
 F src/trigger.c ad6ab9452715fa9a8075442e15196022275b414b9141b566af8cdb7a1605f2b0
-F src/update.c 94a803cf0e45208d12952250500c4210f9ca1b6401fc822033009484f2d39331
+F src/update.c 9a3fc67079371bf9c21b38926f87d812cb0888df6ec0cc00f17117ba44f23519
 F src/upsert.c 5303dc6c518fa7d4b280ec65170f465c7a70b7ac2b22491598f6d0b4875b3145
 F src/utf.c ee39565f0843775cc2c81135751ddd93eceb91a673ea2c57f61c76f288b041a0
-F src/util.c c2aa170f2eb429235b1dddce8952770787ffa5124dc89d405bfbe8ebad8e7ebd
+F src/util.c b3532a95ad56db67b3acd3955e688e4cb80ebec6fd1f459a8eb51cceedd6de69
 F src/vacuum.c b1dd6d73869229b6e08bac910ac011dc9da42e3120ec2b7241accc5a752bd419
-F src/vdbe.c 017239fcce6f09ce356353ceb7cd2ef142a537433055dd35a231480ba73295c7
+F src/vdbe.c 6db2c0f04ffff4e26524b18e3f3c8f50a39aae2fee16cbfb4cd5a420ddecfe48
 F src/vdbe.h 41485521f68e9437fdb7ec4a90f9d86ab294e9bb8281e33b235915e29122cfc0
-F src/vdbeInt.h cd829ff67fc18aff2476fe3209262ba8671cb43d51cb6913de4a670e37d2fbe3
-F src/vdbeapi.c 0cba9fe6e860e46bfb5e45a76a8c2c6ccd5ebc8f954319e4288e7793c2eca88c
+F src/vdbeInt.h 949669dfd8a41550d27dcb905b494f2ccde9a2e6c1b0b04daa1227e2e74c2b2c
+F src/vdbeapi.c f37822f215740ede2a8fcae99bc13f2cc3a72dd0e1d22b81b9298c5ca67dbc38
 F src/vdbeaux.c e4ff54897dca508b3c3726973a1cb08f09d81cbe13c0c36012d9c2572402327c
 F src/vdbeblob.c 2516697b3ee8154eb8915f29466fb5d4f1ae39ee8b755ea909cefaf57ec5e2ce
-F src/vdbemem.c adb5877dc54330865e45e0fba50f6455c1d9d8b83434c59f0e3d2d2a0b9f0e58
+F src/vdbemem.c 317b9f48708139db6239ade40c7980b4bc8233168383690d588dad6d8437f722
 F src/vdbesort.c 0d40dca073c94e158ead752ef4225f4fee22dee84145e8c00ca2309afb489015
 F src/vdbetrace.c fe0bc29ebd4e02c8bc5c1945f1d2e6be5927ec12c06d89b03ef2a4def34bf823
 F src/vdbevtab.c 57fa8f56478e5b5cb558cb425e7878515e0a105c54f96f1d1bbf4b9433529254
@@ -736,7 +736,7 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c 6e1705125b58635ce9ed534f4d26942e4a5e8b5a33219c88f436a9e4691026d4
 F src/wal.h dd2cd9880f308a1bda0a72f36a29c3d4388d47db45f321ebe936a378ac845e32
 F src/walker.c 7c7ea0115345851c3da4e04e2e239a29983b61fb5b038b94eede6aba462640e2
-F src/where.c 477fcc5e561ef169e6002499602af6b805156c2aae6b2f5c2c93ef8c1cd64768
+F src/where.c b8917792f1e0dbfa28fb29e6cd3d560060d69667be0ba4c491cbc772363264f5
 F src/whereInt.h c7d19902863beadec1d04e66aca39c0bcd60b74f05f0eaa7422c7005dfc5d51a
 F src/wherecode.c 5d77db30a2a3dd532492ae882de114edba2fae672622056b1c7fd61f5917a8f1
 F src/whereexpr.c dc5096eca5ed503999be3bdee8a90c51361289a678d396a220912e9cb73b3c00
@@ -930,7 +930,7 @@ F test/corruptH.test 79801d97ec5c2f9f3c87739aa1ec2eb786f96454
 F test/corruptI.test 9d8cbf6214e492abe9e822e759b9751ae336cec0a6fe3ff3b37bfbd8ff9c22ca
 F test/corruptJ.test 4d5ccc4bf959464229a836d60142831ef76a5aa4
 F test/corruptK.test 5b4212fe346699831c5ad559a62c54e11c0611bdde1ea8423a091f9c01aa32af
-F test/corruptL.test b42978028afc5eefc8b51d8d7cd6a9344ba7362d7ed4511ee2070f56e06d5a1c
+F test/corruptL.test 504d90502d9993440226edc355d2275524b89064ea3df5ee5c27f7028ec59d07
 F test/corruptM.test 7d574320e08c1b36caa3e47262061f186367d593a7e305d35f15289cc2c3e067
 F test/corruptN.test 57985a0737f5e008283a91c24630cd3c7003d3c7b62824edaa21258e46da9455
 F test/cost.test b11cdbf9f11ffe8ef99c9881bf390e61fe92baf2182bad1dbe6de59a7295c576
@@ -1159,7 +1159,7 @@ F test/fuzzdata4.db b502c7d5498261715812dd8b3c2005bad08b3a26e6489414bd13926cd3e4
 F test/fuzzdata5.db e35f64af17ec48926481cfaf3b3855e436bd40d1cfe2d59a9474cb4b748a52a5
 F test/fuzzdata6.db b8725a5f5cf7a3b7241a9038e57ca7e7cc8c3f4d86b44bd770617bda245ab2b0
 F test/fuzzdata7.db 0166b56fd7a6b9636a1d60ef0a060f86ddaecf99400a666bb6e5bbd7199ad1f2
-F test/fuzzdata8.db f6c2f2af4deaaae0ddb3310d509c2659990794aa653dc501b80a0534c3493f80
+F test/fuzzdata8.db 40c85daae47da64387c3dab7bbd99c21e425c0bfdb4b149cb685b1ab474a2cb4
 F test/fuzzer1.test 3d4c4b7e547aba5e5511a2991e3e3d07166cfbb8
 F test/fuzzer2.test a85ef814ce071293bce1ad8dffa217cbbaad4c14
 F test/fuzzerfault.test f64c4aef4c9e9edf1d6dc0d3f1e65dcc81e67c996403c88d14f09b74807a42bc
@@ -1792,7 +1792,7 @@ F test/unique.test 93f8b2ef5ea51b9495f8d6493429b1fd0f465264
 F test/unique2.test 3674e9f2a3f1fbbfd4772ac74b7a97090d0f77d2
 F test/unixexcl.test d936ba2b06794018e136418addd59a2354eeae97
 F test/unordered.test 0edaf3411d300693bca595897c5201421c6c5ec787990a1dfe2f7f60ae93f1e2
-F test/update.test 90772ede84cfc779fc3d31884a84ec4c74deb501eeb09a1c6c91c03d8e94c0d8
+F test/update.test 85d3f46d0863033370bd881b1097f5694369a8730e53c5f85d96f32b7b310b47
 F test/update2.test 67455bc61fcbcf96923c45b3bc4f87bc72be7d67575ad35f134906148c7b06d3
 F test/upfrom1.tcl 8859d9d437f03b44174c4524a7a734a391fd4526fcff65be08285dafc9dc9041
 F test/upfrom1.test 8cb06689e99cd707d884faa16da0e8eb26ff658bb01c47ddf72fadade666e6e1
@@ -1906,7 +1906,7 @@ F test/where3.test 5b4ffc0ac2ea0fe92f02b1244b7531522fe4d7bccf6fa8741d54e82c10e67
 F test/where4.test 4a371bfcc607f41d233701bdec33ac2972908ba8
 F test/where5.test fdf66f96d29a064b63eb543e28da4dfdccd81ad2
 F test/where6.test 5da5a98cec820d488e82708301b96cb8c18a258b
-F test/where7.test 1c1bf436bf31b913d4764a2b62ac6e98b9681e5c7ae2b562605592a56b7e946b
+F test/where7.test 15041c7a5838f3bac98f3fb933709674a0b59367664e88fafaf105ff7416eb07
 F test/where8.test 461ca40265ed996a6305da99bb024b0e41602bb586acf544c08f95922358e49f
 F test/where9.test 2db942671a002621eff4f713e347bb25243295f79d8990297cd160bebcfde3f7
 F test/whereA.test 9d1077b117f1b68d5f739d94f36956c36cf995eb87bb19b77b2e81af020edd20
@@ -1980,7 +1980,7 @@ F tool/GetFile.cs 47852aa0d806fe47ed1ac5138bdce7f000fe87aaa7f28107d0cb1e26682aeb
 F tool/GetTclKit.bat d84033c6a93dfe735d247f48ba00292a1cc284dcf69963e5e672444e04534bbf
 F tool/Replace.cs 02c67258801c2fb5f63231e0ac0f220b4b36ba91
 F tool/build-all-msvc.bat c817b716e0edeecaf265a6775b63e5f45c34a6544f1d4114a222701ed5ac79ab x
-F tool/build-shell.sh 950f47c6174f1eea171319438b93ba67ff5bf367
+F tool/build-shell.sh f193b5e3eb4afcb4abbf96bf1475be6cfb74763ee2e50c82bc7ca105e8a136c5
 F tool/cg_anno.tcl c1f875f5a4c9caca3d59937b16aff716f8b1883935f1b4c9ae23124705bc8099 x
 F tool/checkSpacing.c 810e51703529a204fc4e1eb060e9ab663e3c06d2
 F tool/custom.txt 6cdf298f43e1db4bb91406d14777669b8fb1df790837823fa6754c4308decc27
@@ -2063,7 +2063,7 @@ F tool/varint.c 5d94cb5003db9dbbcbcc5df08d66f16071aee003
 F tool/vdbe-compress.tcl 1dcb7632e57cf57105248029e6e162fddaf6c0fccb3bb9e6215603752c5a2d4a
 F tool/vdbe_profile.tcl 3ac5a4a9449f4baf77059358ea050db3e34395ccf59c5464d29b91746d5b961e
 F tool/warnings-clang.sh bbf6a1e685e534c92ec2bfba5b1745f34fb6f0bc2a362850723a9ee87c1b31a7
-F tool/warnings.sh ab651bb82586c43ff8b560beceac959735bf917b44c5e0f67ba3426e474f29f8
+F tool/warnings.sh 49a486c5069de041aedcbde4de178293e0463ae9918ecad7539eedf0ec77a139
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
 F vsixtest/App.xaml b76d3b48860e7454775c47ea38ffea9c4abe3e85
 F vsixtest/App.xaml.cpp 41158ee43269820136fa3bba00c0bd91b26cc38b650ee392aec2a8d823e54318
@@ -2086,8 +2086,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P a6f344399472e211941dffa6586a83fc1740c60e807e85387080a88c9c54658d c1fa1cb5e0c420614481636f3ce2dd9ad2142274bb7b37d39e5c26228317f992
-R ca3ad5620f1225e6ce92f51709515fd0
+P 1d6ded3234bbfa3226ef718eec8d0ce06ae2844628866cb6197383c9bf06267c 6fa71e11197111ab52d1983b35190899a5881dcb9ed822488c92bc839c72cb55
+R b9c55641cb16099f76bc77535273a425
 U drh
-Z 026c14fcd8a2733b517841db43bd86ef
+Z 640d187b55e31c3095d500eb8d395e77
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index d83b2d819b..2272f288bb 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-1d6ded3234bbfa3226ef718eec8d0ce06ae2844628866cb6197383c9bf06267c
\ No newline at end of file
+877ffece0531054f24410c9e4c0b89599a9506689cc97233d33c18b9a15e6308
\ No newline at end of file
diff --git a/src/btreeInt.h b/src/btreeInt.h
index 6c19d09899..6973f86861 100644
--- a/src/btreeInt.h
+++ b/src/btreeInt.h
@@ -180,7 +180,7 @@
 **    0x81 0x00                 becomes  0x00000080
 **    0x82 0x00                 becomes  0x00000100
 **    0x80 0x7f                 becomes  0x0000007f
-**    0x8a 0x91 0xd1 0xac 0x78  becomes  0x12345678
+**    0x81 0x91 0xd1 0xac 0x78  becomes  0x12345678
 **    0x81 0x81 0x81 0x81 0x01  becomes  0x10204081
 **
 ** Variable length integers are used for rowids and to hold the number of
diff --git a/src/delete.c b/src/delete.c
index 641d1ae589..2baff5b3d4 100644
--- a/src/delete.c
+++ b/src/delete.c
@@ -525,7 +525,8 @@ void sqlite3DeleteFrom(
     if( pWInfo==0 ) goto delete_from_cleanup;
     eOnePass = sqlite3WhereOkOnePass(pWInfo, aiCurOnePass);
     assert( IsVirtual(pTab)==0 || eOnePass!=ONEPASS_MULTI );
-    assert( IsVirtual(pTab) || bComplex || eOnePass!=ONEPASS_OFF );
+    assert( IsVirtual(pTab) || bComplex || eOnePass!=ONEPASS_OFF
+            || OptimizationDisabled(db, SQLITE_OnePass) );
     if( eOnePass!=ONEPASS_SINGLE ) sqlite3MultiWrite(pParse);
     if( sqlite3WhereUsesDeferredSeek(pWInfo) ){
       sqlite3VdbeAddOp1(v, OP_FinishSeek, iTabCur);
diff --git a/src/json.c b/src/json.c
index cc39264c05..1e4b94e7aa 100644
--- a/src/json.c
+++ b/src/json.c
@@ -30,25 +30,51 @@
 ** increase for the parser.  (Ubuntu14.10 gcc 4.8.4 x64 with -Os).
 */
 static const char jsonIsSpace[] = {
-  0, 0, 0, 0, 0, 0, 0, 0,     0, 1, 1, 0, 0, 1, 0, 0,
-  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
-  1, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
-  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
-  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
-  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
-  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
-  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
-  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
-  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
-  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
-  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
-  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
-  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
-  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
-  0, 0, 0, 0, 0, 0, 0, 0,     0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 1, 1, 0, 0, 1, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
+  1, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
+
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
 };
 #define fast_isspace(x) (jsonIsSpace[(unsigned char)x])
 
+/*
+** Characters that are special to JSON.  Control charaters,
+** '"' and '\\'.
+*/
+static const char jsonIsOk[256] = {
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
+  1, 1, 0, 1, 1, 1, 1, 0,  1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 0, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
+
+  1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
+  1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1
+};
+
+
 #if !defined(SQLITE_DEBUG) && !defined(SQLITE_COVERAGE_TEST)
 #  define VVA(X)
 #else
@@ -357,11 +383,16 @@ static void jsonAppendString(JsonString *p, const char *zIn, u32 N){
   p->zBuf[p->nUsed++] = '"';
   for(i=0; i<N; i++){
     unsigned char c = ((unsigned const char*)zIn)[i];
-    if( c=='"' || c=='\\' ){
+    if( jsonIsOk[c] ){
+      p->zBuf[p->nUsed++] = c;
+    }else if( c=='"' || c=='\\' ){
       json_simple_escape:
       if( (p->nUsed+N+3-i > p->nAlloc) && jsonGrow(p,N+3-i)!=0 ) return;
       p->zBuf[p->nUsed++] = '\\';
-    }else if( c<=0x1f ){
+      p->zBuf[p->nUsed++] = c;
+    }else if( c=='\'' ){
+      p->zBuf[p->nUsed++] = c;
+    }else{
       static const char aSpecial[] = {
          0, 0, 0, 0, 0, 0, 0, 0, 'b', 't', 'n', 0, 'f', 'r', 0, 0,
          0, 0, 0, 0, 0, 0, 0, 0,   0,   0,   0, 0,   0,   0, 0, 0
@@ -372,6 +403,7 @@ static void jsonAppendString(JsonString *p, const char *zIn, u32 N){
       assert( aSpecial['\n']=='n' );
       assert( aSpecial['\r']=='r' );
       assert( aSpecial['\t']=='t' );
+      assert( c>=0 && c<sizeof(aSpecial) );
       if( aSpecial[c] ){
         c = aSpecial[c];
         goto json_simple_escape;
@@ -381,10 +413,9 @@ static void jsonAppendString(JsonString *p, const char *zIn, u32 N){
       p->zBuf[p->nUsed++] = 'u';
       p->zBuf[p->nUsed++] = '0';
       p->zBuf[p->nUsed++] = '0';
-      p->zBuf[p->nUsed++] = '0' + (c>>4);
-      c = "0123456789abcdef"[c&0xf];
+      p->zBuf[p->nUsed++] = "0123456789abcdef"[c>>4];
+      p->zBuf[p->nUsed++] = "0123456789abcdef"[c&0xf];
     }
-    p->zBuf[p->nUsed++] = c;
   }
   p->zBuf[p->nUsed++] = '"';
   assert( p->nUsed<p->nAlloc );
@@ -1070,7 +1101,9 @@ static int jsonParseAddNode(
   if( pParse->nNode>=pParse->nAlloc ){
     return jsonParseAddNodeExpand(pParse, eType, n, zContent);
   }
+  assert( pParse->aNode!=0 );
   p = &pParse->aNode[pParse->nNode];
+  assert( p!=0 );
   p->eType = (u8)(eType & 0xff);
   p->jnFlags = (u8)(eType >> 8);
   VVA( p->eU = zContent ? 1 : 0 );
@@ -1090,6 +1123,8 @@ static void jsonParseAddNodeArray(
   JsonNode *aNode,          /* Array of nodes to add */
   u32 nNode                 /* Number of elements in aNew */
 ){
+  assert( aNode!=0 );
+  assert( nNode>=1 );
   if( pParse->nNode + nNode > pParse->nAlloc ){
     u32 nNew = pParse->nNode + nNode;
     JsonNode *aNew = sqlite3_realloc64(pParse->aNode, nNew*sizeof(JsonNode));
@@ -1465,26 +1500,7 @@ json_parse_restart:
   parse_string:
     cDelim = z[i];
     for(j=i+1; 1; j++){
-      static const char aOk[256] = {
-          0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
-          0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
-          1, 1, 0, 1, 1, 1, 1, 0,  1, 1, 1, 1, 1, 1, 1, 1,
-          1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
-          1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
-          1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 0, 1, 1, 1,
-          1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
-          1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
-
-          1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
-          1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
-          1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
-          1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
-          1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
-          1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
-          1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
-          1, 1, 1, 1, 1, 1, 1, 1,  1, 1, 1, 1, 1, 1, 1, 1,
-      };
-      if( aOk[(unsigned char)z[j]] ) continue;
+      if( jsonIsOk[(unsigned char)z[j]] ) continue;
       c = z[j];
       if( c==cDelim ){
         break;
@@ -2672,10 +2688,11 @@ static void jsonPatchFunc(
   UNUSED_PARAMETER(argc);
   pX = jsonParseCached(ctx, argv[0], ctx, 1);
   if( pX==0 ) return;
+  assert( pX->hasMod==0 );
+  pX->hasMod = 1;
   pY = jsonParseCached(ctx, argv[1], ctx, 1);
   if( pY==0 ) return;
   pX->useMod = 1;
-  pX->hasMod = 1;
   pY->useMod = 1;
   pResult = jsonMergePatch(pX, 0, pY->aNode);
   assert( pResult!=0 || pX->oom );
diff --git a/src/main.c b/src/main.c
index 8345923219..7630ed0fc2 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1665,9 +1665,9 @@ static int sqliteDefaultBusyCallback(
   void *ptr,               /* Database connection */
   int count                /* Number of times table has been busy */
 ){
-#if SQLITE_OS_WIN || HAVE_USLEEP
+#if SQLITE_OS_WIN || !defined(HAVE_NANOSLEEP) || HAVE_NANOSLEEP
   /* This case is for systems that have support for sleeping for fractions of
-  ** a second.  Examples:  All windows systems, unix systems with usleep() */
+  ** a second.  Examples:  All windows systems, unix systems with nanosleep() */
   static const u8 delays[] =
      { 1, 2, 5, 10, 15, 20, 25, 25,  25,  50,  50, 100 };
   static const u8 totals[] =
@@ -4160,10 +4160,12 @@ int sqlite3_test_control(int op, ...){
         sqlite3ShowSrcList(0);
         sqlite3ShowWith(0);
         sqlite3ShowUpsert(0);
+#ifndef SQLITE_OMIT_TRIGGER
         sqlite3ShowTriggerStep(0);
         sqlite3ShowTriggerStepList(0);
         sqlite3ShowTrigger(0);
         sqlite3ShowTriggerList(0);
+#endif
 #ifndef SQLITE_OMIT_WINDOWFUNC
         sqlite3ShowWindow(0);
         sqlite3ShowWinFunc(0);
@@ -4470,6 +4472,7 @@ int sqlite3_test_control(int op, ...){
       break;
     }
 
+#if !defined(SQLITE_OMIT_WSD)
     /* sqlite3_test_control(SQLITE_TESTCTRL_USELONGDOUBLE, int X);
     **
     **   X<0     Make no changes to the bUseLongDouble.  Just report value.
@@ -4484,6 +4487,7 @@ int sqlite3_test_control(int op, ...){
       rc = sqlite3Config.bUseLongDouble!=0;
       break;
     }
+#endif
 
 
 #if defined(SQLITE_DEBUG) && !defined(SQLITE_OMIT_WSD)
diff --git a/src/os_unix.c b/src/os_unix.c
index 16be92635d..73be4c97ea 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -6901,12 +6901,17 @@ static int unixRandomness(sqlite3_vfs *NotUsed, int nBuf, char *zBuf){
 ** than the argument.
 */
 static int unixSleep(sqlite3_vfs *NotUsed, int microseconds){
-#if OS_VXWORKS || _POSIX_C_SOURCE >= 199309L
+#if !defined(HAVE_NANOSLEEP) || HAVE_NANOSLEEP+0
   struct timespec sp;
-
   sp.tv_sec = microseconds / 1000000;
   sp.tv_nsec = (microseconds % 1000000) * 1000;
+
+  /* Almost all modern unix systems support nanosleep().  But if you are
+  ** compiling for one of the rare exceptions, you can use
+  ** -DHAVE_NANOSLEEP=0 (perhaps in conjuction with -DHAVE_USLEEP if
+  ** usleep() is available) in order to bypass the use of nanosleep() */
   nanosleep(&sp, NULL);
+
   UNUSED_PARAMETER(NotUsed);
   return microseconds;
 #elif defined(HAVE_USLEEP) && HAVE_USLEEP
diff --git a/src/select.c b/src/select.c
index ce688663da..5dce50e543 100644
--- a/src/select.c
+++ b/src/select.c
@@ -4292,7 +4292,8 @@ static int compoundHasDifferentAffinities(Select *p){
 **        (27b) the subquery is a compound query and the RIGHT JOIN occurs
 **              in any arm of the compound query.  (See also (17g).)
 **
-**  (28)  The subquery is not a MATERIALIZED CTE.
+**  (28)  The subquery is not a MATERIALIZED CTE.  (This is handled
+**        in the caller before ever reaching this routine.)
 **
 **
 ** In this routine, the "p" parameter is a pointer to the outer query.
@@ -4402,9 +4403,9 @@ static int flattenSubquery(
   if( iFrom>0 && (pSubSrc->a[0].fg.jointype & JT_LTORJ)!=0 ){
     return 0;   /* Restriction (27a) */
   }
-  if( pSubitem->fg.isCte && pSubitem->u2.pCteUse->eM10d==M10d_Yes ){
-    return 0;       /* (28) */
-  }
+
+  /* Condition (28) is blocked by the caller */
+  assert( !pSubitem->fg.isCte || pSubitem->u2.pCteUse->eM10d!=M10d_Yes );
 
   /* Restriction (17): If the sub-query is a compound SELECT, then it must
   ** use only the UNION ALL operator. And none of the simple select queries
@@ -7285,6 +7286,14 @@ int sqlite3Select(
       goto select_end;
     }
 
+    /* Do not attempt the usual optimizations (flattening and ORDER BY
+    ** elimination) on a MATERIALIZED common table expression because
+    ** a MATERIALIZED common table expression is an optimization fence.
+    */
+    if( pItem->fg.isCte && pItem->u2.pCteUse->eM10d==M10d_Yes ){
+      continue;
+    }
+
     /* Do not try to flatten an aggregate subquery.
     **
     ** Flattening an aggregate subquery is only possible if the outer query
@@ -7314,6 +7323,8 @@ int sqlite3Select(
     **            (a)  The outer query has a different ORDER BY clause
     **            (b)  The subquery is part of a join
     **          See forum post 062d576715d277c8
+    **
+    ** Also retain the ORDER BY if the OmitOrderBy optimization is disabled.
     */
     if( pSub->pOrderBy!=0
      && (p->pOrderBy!=0 || pTabList->nSrc>1)      /* Condition (5) */
diff --git a/src/sqlite.h.in b/src/sqlite.h.in
index d6f7f4178d..819f775d6b 100644
--- a/src/sqlite.h.in
+++ b/src/sqlite.h.in
@@ -4426,10 +4426,10 @@ int sqlite3_stmt_isexplain(sqlite3_stmt *pStmt);
 ** METHOD: sqlite3_stmt
 **
 ** The sqlite3_stmt_explain(S,E) interface changes the EXPLAIN
-** setting for prepared statement S.  If E is zero, then S becomes
+** setting for [prepared statement] S.  If E is zero, then S becomes
 ** a normal prepared statement.  If E is 1, then S behaves as if
-** its SQL text began with "EXPLAIN".  If E is 2, then S behaves as if
-** its SQL text began with "EXPLAIN QUERY PLAN".
+** its SQL text began with "[EXPLAIN]".  If E is 2, then S behaves as if
+** its SQL text began with "[EXPLAIN QUERY PLAN]".
 **
 ** Calling sqlite3_stmt_explain(S,E) might cause S to be reprepared.
 ** SQLite tries to avoid a reprepare, but a reprepare might be necessary
@@ -4437,8 +4437,8 @@ int sqlite3_stmt_isexplain(sqlite3_stmt *pStmt);
 **
 ** Because of the potential need to reprepare, a call to
 ** sqlite3_stmt_explain(S,E) will fail with SQLITE_ERROR if S cannot be
-** reprepared because it was created using sqlite3_prepare() instead of
-** the newer sqlite_prepare_v2() or sqlite3_prepare_v3() interfaces and
+** reprepared because it was created using [sqlite3_prepare()] instead of
+** the newer [sqlite3_prepare_v2()] or [sqlite3_prepare_v3()] interfaces and
 ** hence has no saved SQL text with which to reprepare.
 **
 ** Changing the explain setting for a prepared statement does not change
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index c80322ad08..5eb036044b 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -1899,6 +1899,7 @@ struct sqlite3 {
 #define SQLITE_IndexedExpr    0x01000000 /* Pull exprs from index when able */
 #define SQLITE_Coroutines     0x02000000 /* Co-routines for subqueries */
 #define SQLITE_NullUnusedCols 0x04000000 /* NULL unused columns in subqueries */
+#define SQLITE_OnePass        0x08000000 /* Single-pass DELETE and UPDATE */
 #define SQLITE_AllOpts        0xffffffff /* All optimizations */
 
 /*
@@ -3815,7 +3816,7 @@ struct Parse {
     int addrCrTab;         /* Address of OP_CreateBtree on CREATE TABLE */
     Returning *pReturning; /* The RETURNING clause */
   } u1;
-  u32 nQueryLoop;      /* Est number of iterations of a query (10*log2(N)) */
+  LogEst nQueryLoop;   /* Est number of iterations of a query (10*log2(N)) */
   u32 oldmask;         /* Mask of old.* columns referenced */
   u32 newmask;         /* Mask of new.* columns referenced */
 #ifndef SQLITE_OMIT_PROGRESS_CALLBACK
diff --git a/src/test1.c b/src/test1.c
index 453a6b3631..237c61b39e 100644
--- a/src/test1.c
+++ b/src/test1.c
@@ -8060,6 +8060,7 @@ static int SQLITE_TCLAPI optimization_control(
     { "push-down",           SQLITE_PushDown       },
     { "balanced-merge",      SQLITE_BalancedMerge  },
     { "propagate-const",     SQLITE_PropagateConst },
+    { "one-pass",            SQLITE_OnePass        },
   };
 
   if( objc!=4 ){
diff --git a/src/update.c b/src/update.c
index 7d0afa69bf..c2d8f0fffb 100644
--- a/src/update.c
+++ b/src/update.c
@@ -752,7 +752,7 @@ void sqlite3Update(
        && !hasFK
        && !chngKey
        && !bReplace
-       && (sNC.ncFlags & NC_Subquery)==0
+       && (pWhere==0 || !ExprHasProperty(pWhere, EP_Subquery))
       ){
         flags |= WHERE_ONEPASS_MULTIROW;
       }
diff --git a/src/util.c b/src/util.c
index 1200aef0e3..25fd6ff597 100644
--- a/src/util.c
+++ b/src/util.c
@@ -591,7 +591,12 @@ do_atof_calc:
       while( e<=-10  ){ e+=10;  r *= 1.0e-10L;  }
       while( e<=-1   ){ e+=1;   r *= 1.0e-01L;  }
     }
-    *pResult = r;
+    assert( r>=0.0 );
+    if( r>+1.7976931348623157081452742373e+308L ){
+      *pResult = +INFINITY;
+    }else{
+      *pResult = (double)r;
+    }
   }else{
     double rr[2];
     u64 s2;
diff --git a/src/vdbe.c b/src/vdbe.c
index 4c43cc95b5..68d6604052 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -708,6 +708,8 @@ static SQLITE_NOINLINE int vdbeColumnFromOverflow(
   int iCol,             /* The column to read */
   int t,                /* The serial-type code for the column value */
   i64 iOffset,          /* Offset to the start of the content value */
+  u32 cacheStatus,      /* Current Vdbe.cacheCtr value */
+  u32 colCacheCtr,      /* Current value of the column cache counter */
   Mem *pDest            /* Store the value into this register. */
 ){
   int rc;
@@ -716,12 +718,16 @@ static SQLITE_NOINLINE int vdbeColumnFromOverflow(
   int len = sqlite3VdbeSerialTypeLen(t);
   assert( pC->eCurType==CURTYPE_BTREE );
   if( len>db->aLimit[SQLITE_LIMIT_LENGTH] ) return SQLITE_TOOBIG;
-  if( len > 4000 ){
+  if( len > 4000 && pC->pKeyInfo==0 ){
     /* Cache large column values that are on overflow pages using
     ** an RCStr (reference counted string) so that if they are reloaded,
     ** that do not have to be copied a second time.  The overhead of
     ** creating and managing the cache is such that this is only
     ** profitable for larger TEXT and BLOB values.
+    **
+    ** Only do this on table-btrees so that writes to index-btrees do not
+    ** need to clear the cache.  This buys performance in the common case
+    ** in exchange for generality.
     */
     VdbeTxtBlbCache *pCache;
     char *pBuf;
@@ -733,6 +739,8 @@ static SQLITE_NOINLINE int vdbeColumnFromOverflow(
     pCache = pC->pCache;
     if( pCache->pCValue==0
      || pCache->iCol!=iCol
+     || pCache->cacheStatus!=cacheStatus
+     || pCache->colCacheCtr!=colCacheCtr
      || pCache->iOffset!=sqlite3BtreeOffset(pC->uc.pCursor)
     ){
       if( pCache->pCValue ) sqlite3RCStrUnref(pCache->pCValue);
@@ -744,6 +752,8 @@ static SQLITE_NOINLINE int vdbeColumnFromOverflow(
       pBuf[len+1] = 0;
       pBuf[len+2] = 0;
       pCache->iCol = iCol;
+      pCache->cacheStatus = cacheStatus;
+      pCache->colCacheCtr = colCacheCtr;
       pCache->iOffset = sqlite3BtreeOffset(pC->uc.pCursor);
     }else{
       pBuf = pCache->pCValue;
@@ -814,6 +824,7 @@ int sqlite3VdbeExec(
   Mem *pIn2 = 0;             /* 2nd input operand */
   Mem *pIn3 = 0;             /* 3rd input operand */
   Mem *pOut = 0;             /* Output operand */
+  u32 colCacheCtr = 0;       /* Column cache counter */
 #if defined(SQLITE_ENABLE_STMT_SCANSTATUS) || defined(VDBE_PROFILE)
   u64 *pnCycle = 0;
   int bStmtScanStatus = IS_STMT_SCANSTATUS(db)!=0;
@@ -3145,7 +3156,7 @@ op_column_restart:
               || (t>=12 && ((t&1)==0 || p5==OPFLAG_BYTELENARG))
              )
         )
-     || (len = sqlite3VdbeSerialTypeLen(t))==0
+     || sqlite3VdbeSerialTypeLen(t)==0
     ){
       /* Content is irrelevant for
       **    1. the typeof() function,
@@ -3162,7 +3173,8 @@ op_column_restart:
       */
       sqlite3VdbeSerialGet((u8*)sqlite3CtypeMap, t, pDest);
     }else{
-      rc = vdbeColumnFromOverflow(pC, p2, t, aOffset[p2], pDest);
+      rc = vdbeColumnFromOverflow(pC, p2, t, aOffset[p2],
+                p->cacheCtr, colCacheCtr, pDest);
       if( rc ){
         if( rc==SQLITE_NOMEM ) goto no_mem;
         if( rc==SQLITE_TOOBIG ) goto too_big;
@@ -5736,6 +5748,7 @@ case OP_Insert: {
   );
   pC->deferredMoveto = 0;
   pC->cacheStatus = CACHE_STALE;
+  colCacheCtr++;
 
   /* Invoke the update-hook if required. */
   if( rc ) goto abort_due_to_error;
@@ -5896,6 +5909,7 @@ case OP_Delete: {
 
   rc = sqlite3BtreeDelete(pC->uc.pCursor, pOp->p5);
   pC->cacheStatus = CACHE_STALE;
+  colCacheCtr++;
   pC->seekResult = 0;
   if( rc ) goto abort_due_to_error;
 
diff --git a/src/vdbeInt.h b/src/vdbeInt.h
index f424559929..2a23c3f285 100644
--- a/src/vdbeInt.h
+++ b/src/vdbeInt.h
@@ -159,6 +159,8 @@ struct VdbeTxtBlbCache {
   char *pCValue;        /* A RCStr buffer to hold the value */
   i64 iOffset;          /* File offset of the row being cached */
   int iCol;             /* Column for which the cache is valid */
+  u32 cacheStatus;      /* Vdbe.cacheCtr value */
+  u32 colCacheCtr;      /* Column cache counter */
 };
 
 /*
diff --git a/src/vdbeapi.c b/src/vdbeapi.c
index cb631413c4..cc58e7a877 100644
--- a/src/vdbeapi.c
+++ b/src/vdbeapi.c
@@ -1863,19 +1863,23 @@ int sqlite3_stmt_isexplain(sqlite3_stmt *pStmt){
 int sqlite3_stmt_explain(sqlite3_stmt *pStmt, int eMode){
   Vdbe *v = (Vdbe*)pStmt;
   int rc;
-  if( v->eVdbeState!=VDBE_READY_STATE ) return SQLITE_BUSY; 
-  if( v->explain==eMode ) return SQLITE_OK;
-  if( v->zSql==0 || eMode<0 || eMode>2 ) return SQLITE_ERROR;
   sqlite3_mutex_enter(v->db->mutex);
-  if( v->nMem>=10 && (eMode!=2 || v->haveEqpOps) ){
+  if( v->explain==eMode ){
+    rc = SQLITE_OK;
+  }else if( eMode<0 || eMode>2 ){
+    rc = SQLITE_ERROR;
+  }else if( (v->prepFlags & SQLITE_PREPARE_SAVESQL)==0 ){
+    rc = SQLITE_ERROR;
+  }else if( v->eVdbeState!=VDBE_READY_STATE ){
+    rc = SQLITE_BUSY;
+  }else if( v->nMem>=10 && (eMode!=2 || v->haveEqpOps) ){
     /* No reprepare necessary */
     v->explain = eMode;
     rc = SQLITE_OK;
   }else{
-    int haveEqpOps = v->explain==2 || v->haveEqpOps;
     v->explain = eMode;
     rc = sqlite3Reprepare(v);
-    v->haveEqpOps = haveEqpOps!=0;
+    v->haveEqpOps = eMode==2;
   }
   if( v->explain ){
     v->nResColumn = 12 - 4*v->explain;
diff --git a/src/vdbemem.c b/src/vdbemem.c
index 07fb8feee8..e25efc9771 100644
--- a/src/vdbemem.c
+++ b/src/vdbemem.c
@@ -322,7 +322,10 @@ int sqlite3VdbeMemClearAndResize(Mem *pMem, int szNew){
 ** this routine is a no-op.
 */
 void sqlite3VdbeMemZeroTerminateIfAble(Mem *pMem){
-  if( (pMem->flags & (MEM_Str|MEM_Term))!=MEM_Str ) return;
+  if( (pMem->flags & (MEM_Str|MEM_Term|MEM_Ephem|MEM_Static))!=MEM_Str ){
+    /* pMem must be a string, and it cannot be an ephemeral or static string */
+    return;
+  }
   if( pMem->enc!=SQLITE_UTF8 ) return;
   if( NEVER(pMem->z==0) ) return;
   if( pMem->flags & MEM_Dyn ){
@@ -338,7 +341,7 @@ void sqlite3VdbeMemZeroTerminateIfAble(Mem *pMem){
       pMem->flags |= MEM_Term;
       return;
     }
-  }else if( pMem->szMalloc>0 && pMem->szMalloc >= pMem->n+1 ){
+  }else if( pMem->szMalloc >= pMem->n+1 ){
     pMem->z[pMem->n] = 0;
     pMem->flags |= MEM_Term;
     return;
diff --git a/src/where.c b/src/where.c
index 35b9056ffe..213df42230 100644
--- a/src/where.c
+++ b/src/where.c
@@ -2535,7 +2535,7 @@ static WhereLoop **whereLoopFindLesser(
 
     /* If pTemplate is always better than p, then cause p to be overwritten
     ** with pTemplate.  pTemplate is better than p if:
-    **   (1)  pTemplate has no more dependences than p, and
+    **   (1)  pTemplate has no more dependencies than p, and
     **   (2)  pTemplate has an equal or lower cost than p.
     */
     if( (p->prereq & pTemplate->prereq)==pTemplate->prereq   /* (1)  */
@@ -5003,7 +5003,8 @@ static int wherePathSolver(WhereInfo *pWInfo, LogEst nRowEst){
   ** For joins of 3 or more tables, track the 10 best paths */
   mxChoice = (nLoop<=1) ? 1 : (nLoop==2 ? 5 : 10);
   assert( nLoop<=pWInfo->pTabList->nSrc );
-  WHERETRACE(0x002, ("---- begin solver.  (nRowEst=%d)\n", nRowEst));
+  WHERETRACE(0x002, ("---- begin solver.  (nRowEst=%d, nQueryLoop=%d)\n",
+                     nRowEst, pParse->nQueryLoop));
 
   /* If nRowEst is zero and there is an ORDER BY clause, ignore it. In this
   ** case the purpose of this call is to estimate the number of rows returned
@@ -5757,6 +5758,28 @@ static SQLITE_NOINLINE void whereAddIndexedExpr(
   }
 }
 
+/*
+** Set the reverse-scan order mask to one for all tables in the query
+** with the exception of MATERIALIZED common table expressions that have
+** their own internal ORDER BY clauses.
+**
+** This implements the PRAGMA reverse_unordered_selects=ON setting.
+** (Also SQLITE_DBCONFIG_REVERSE_SCANORDER).
+*/
+static SQLITE_NOINLINE void whereReverseScanOrder(WhereInfo *pWInfo){
+  int ii;
+  for(ii=0; ii<pWInfo->pTabList->nSrc; ii++){
+    SrcItem *pItem = &pWInfo->pTabList->a[ii];
+    if( !pItem->fg.isCte
+     || pItem->u2.pCteUse->eM10d!=M10d_Yes
+     || NEVER(pItem->pSelect==0)
+     || pItem->pSelect->pOrderBy==0
+    ){
+      pWInfo->revMask |= MASKBIT(ii);
+    }
+  }
+}
+
 /*
 ** Generate the beginning of the loop used for WHERE clause processing.
 ** The return value is a pointer to an opaque structure that contains
@@ -6121,8 +6144,9 @@ WhereInfo *sqlite3WhereBegin(
        if( db->mallocFailed ) goto whereBeginError;
     }
   }
+  assert( pWInfo->pTabList!=0 );
   if( pWInfo->pOrderBy==0 && (db->flags & SQLITE_ReverseOrder)!=0 ){
-     pWInfo->revMask = ALLBITS;
+    whereReverseScanOrder(pWInfo);
   }
   if( pParse->nErr ){
     goto whereBeginError;
@@ -6222,6 +6246,7 @@ WhereInfo *sqlite3WhereBegin(
         0!=(wctrlFlags & WHERE_ONEPASS_MULTIROW)
      && !IsVirtual(pTabList->a[0].pTab)
      && (0==(wsFlags & WHERE_MULTI_OR) || (wctrlFlags & WHERE_DUPLICATES_OK))
+     && OptimizationEnabled(db, SQLITE_OnePass)
     )){
       pWInfo->eOnePass = bOnerow ? ONEPASS_SINGLE : ONEPASS_MULTI;
       if( HasRowid(pTabList->a[0].pTab) && (wsFlags & WHERE_IDX_ONLY) ){
diff --git a/test/corruptL.test b/test/corruptL.test
index 65d9821b35..cf38764415 100644
--- a/test/corruptL.test
+++ b/test/corruptL.test
@@ -1269,6 +1269,7 @@ do_test 15.0 {
 }]} {}
 
 extra_schema_checks 0
+optimization_control db one-pass off
 do_catchsql_test 15.1 {
   PRAGMA cell_size_check = 0;
   UPDATE c1 SET c= NOT EXISTS(SELECT 1 FROM c1 ORDER BY (SELECT 1 FROM c1 ORDER BY a)) +10 WHERE d BETWEEN 4 AND 7;
diff --git a/test/fuzzdata8.db b/test/fuzzdata8.db
index a4969047aa..6b434f6bbf 100644
Binary files a/test/fuzzdata8.db and b/test/fuzzdata8.db differ
diff --git a/test/update.test b/test/update.test
index 47b6029bee..bf7666662a 100644
--- a/test/update.test
+++ b/test/update.test
@@ -764,5 +764,27 @@ do_execsql_test update-21.4 {
   SELECT * FROM t1 ORDER BY vkey, c5;
   ROLLBACK;
 } {6 -54 100 NULL}
+# Follow-up on 2023-07-31 (forum post https://sqlite.org/forum/forumpost/8ab195fd44e75ed0):
+# Only disable one-pass if the subquery is in the WHERE clause.  The SET expressions
+# do not count.
+do_execsql_test update-21.11 {
+  DROP TABLE t1;
+  CREATE TABLE t1(a INTEGER PRIMARY KEY, b INT);
+  CREATE TABLE t2(d INT);
+}
+do_eqp_test update-21.12 {
+  WITH t3(x,y) AS (SELECT d, row_number()OVER() FROM t2)
+    UPDATE t1 SET b=(SELECT y FROM t3 WHERE t1.a=t3.x);
+} {
+  QUERY PLAN
+  |--SCAN t1
+  `--CORRELATED SCALAR SUBQUERY xxxxxx
+     |--CO-ROUTINE t3
+     |  |--CO-ROUTINE (subquery-xxxxxx)
+     |  |  `--SCAN t2
+     |  `--SCAN (subquery-xxxxxx)
+     |--BLOOM FILTER ON t3 (x=?)
+     `--SEARCH t3 USING AUTOMATIC COVERING INDEX (x=?)
+}
 
 finish_test
diff --git a/test/where7.test b/test/where7.test
index f76e8aba8b..681684b809 100644
--- a/test/where7.test
+++ b/test/where7.test
@@ -47,18 +47,33 @@ do_test where7-1.1 {
     SELECT * FROM t1;
   }
 } {1 2 3 4 2 3 4 5 3 4 6 8 4 5 10 15 5 10 100 1000}
-do_execsql_test where7-1.1.1 {
-  CREATE TABLE t(a);
-  CREATE INDEX ta ON t(a);
-  INSERT INTO t(a) VALUES(1),(2);
-  SELECT * FROM t ORDER BY a;
-  SELECT * FROM t WHERE a<2 OR a<3 ORDER BY a;
-  PRAGMA count_changes=ON;
-  DELETE FROM t WHERE a<2 OR a<3;
-  SELECT * FROM t;
-  PRAGMA count_changes=OFF;
-  DROP TABLE t;
-} {1 2 1 2 2}
+if {[permutation] != "no_optimization"} {
+  do_execsql_test where7-1.1.1 {
+    CREATE TABLE t(a);
+    CREATE INDEX ta ON t(a);
+    INSERT INTO t(a) VALUES(1),(2);
+    SELECT * FROM t ORDER BY a;
+    SELECT * FROM t WHERE a<2 OR a<3 ORDER BY a;
+    PRAGMA count_changes=ON;
+    DELETE FROM t WHERE a<2 OR a<3;
+    SELECT * FROM t;
+    PRAGMA count_changes=OFF;
+    DROP TABLE t;
+  } {1 2 1 2 2}
+} else {
+  do_execsql_test where7-1.1.1-noopt {
+    CREATE TABLE t(a);
+    CREATE INDEX ta ON t(a);
+    INSERT INTO t(a) VALUES(1),(2);
+    SELECT * FROM t ORDER BY a;
+    SELECT * FROM t WHERE a<2 OR a<3 ORDER BY a;
+    PRAGMA count_changes=ON;
+    DELETE FROM t WHERE a<2 OR a<3;
+    SELECT * FROM t;
+    PRAGMA count_changes=OFF;
+    DROP TABLE t;
+  } {1 2 1 2 3}
+}
 do_test where7-1.2 {
   count_steps {
     SELECT a FROM t1 WHERE b=3 OR c=6 ORDER BY a
diff --git a/tool/build-shell.sh b/tool/build-shell.sh
index 6a48299d73..a57f753039 100644
--- a/tool/build-shell.sh
+++ b/tool/build-shell.sh
@@ -16,7 +16,6 @@ gcc -o sqlite3 -g -Os -I. \
    -DSQLITE_ENABLE_FTS4 \
    -DSQLITE_ENABLE_RTREE \
    -DHAVE_READLINE \
-   -DHAVE_USLEEP=1 \
    ../sqlite/src/shell.c \
    ../sqlite/src/test_vfstrace.c \
    sqlite3.c -ldl -lreadline -lncurses
diff --git a/tool/warnings.sh b/tool/warnings.sh
index 60d2b42100..2b962d15ed 100644
--- a/tool/warnings.sh
+++ b/tool/warnings.sh
@@ -32,7 +32,6 @@ if test x`uname` = 'xLinux'; then
 echo '********** Android configuration ******************************'
 echo '**********    ' Options: $WARNING_ANDROID_OPTS
 gcc -c \
-  -DHAVE_USLEEP=1 \
   -DSQLITE_HAVE_ISNAN \
   -DSQLITE_DEFAULT_JOURNAL_SIZE_LIMIT=1048576 \
   -DSQLITE_THREADSAFE=2 \