Index: Makefile.in
==================================================================
--- Makefile.in
+++ Makefile.in
@@ -534,10 +534,13 @@
 sqlite3$(TEXE):	$(TOP)/src/shell.c libsqlite3.la sqlite3.h
 	$(LTLINK) $(READLINE_FLAGS) \
 		-o $@ $(TOP)/src/shell.c libsqlite3.la \
 		$(LIBREADLINE) $(TLIBS) -rpath "$(libdir)"
 
+sqldiff$(EXE):	$(TOP)/tool/sqldiff.c sqlite3.c sqlite3.h
+	$(LTLINK) -o $@ $(TOP)/tool/sqldiff.c	sqlite3.c $(TLIBS)
+
 mptester$(EXE):	sqlite3.c $(TOP)/mptest/mptest.c
 	$(LTLINK) -o $@ -I. $(TOP)/mptest/mptest.c sqlite3.c \
 		$(TLIBS) -rpath "$(libdir)"
 
 MPTEST1=./mptester$(EXE) mptest.db $(TOP)/mptest/crash01.test --repeat 20

Index: Makefile.msc
==================================================================
--- Makefile.msc
+++ Makefile.msc
@@ -1151,10 +1151,13 @@
 	$(LTLIB) $(LTLIBOPTS) $(LTLIBPATHS) /OUT:$@ tclsqlite.lo libsqlite3.lib $(LIBTCL:tcl=tclstub) $(TLIBS)
 
 sqlite3.exe:	$(TOP)\src\shell.c $(SHELL_CORE_DEP) $(LIBRESOBJS) sqlite3.h
 	$(LTLINK) $(SHELL_COMPILE_OPTS) $(READLINE_FLAGS) $(TOP)\src\shell.c \
 		/link /pdb:sqlite3sh.pdb $(LTLINKOPTS) $(SHELL_LINK_OPTS) $(LTLIBPATHS) $(LIBRESOBJS) $(LIBREADLINE) $(LTLIBS) $(TLIBS)
+
+sqldiff.exe:	$(TOP)\tool\sqldiff.c sqlite3.c sqlite3.h
+	$(LTLINK) $(TOP)\tool\sqldiff.c sqlite3.c
 
 mptester.exe:	$(TOP)\mptest\mptest.c $(SHELL_CORE_DEP) $(LIBRESOBJS) sqlite3.h
 	$(LTLINK) $(SHELL_COMPILE_OPTS) $(TOP)\mptest\mptest.c \
 		/link $(LTLINKOPTS) $(LTLIBPATHS) $(SHELL_LINK_OPTS) $(LIBRESOBJS) $(LIBREADLINE) $(LTLIBS) $(TLIBS)
 

Index: ext/fts3/fts3.c
==================================================================
--- ext/fts3/fts3.c
+++ ext/fts3/fts3.c
@@ -1017,11 +1017,12 @@
   sqlite3 *db,                    /* Database handle */
   const char *zDb,                /* Name of db (i.e. "main", "temp" etc.) */
   const char *zTbl,               /* Name of content table */
   const char ***pazCol,           /* OUT: Malloc'd array of column names */
   int *pnCol,                     /* OUT: Size of array *pazCol */
-  int *pnStr                      /* OUT: Bytes of string content */
+  int *pnStr,                     /* OUT: Bytes of string content */
+  char **pzErr                    /* OUT: error message */
 ){
   int rc = SQLITE_OK;             /* Return code */
   char *zSql;                     /* "SELECT *" statement on zTbl */  
   sqlite3_stmt *pStmt = 0;        /* Compiled version of zSql */
 
@@ -1028,10 +1029,13 @@
   zSql = sqlite3_mprintf("SELECT * FROM %Q.%Q", zDb, zTbl);
   if( !zSql ){
     rc = SQLITE_NOMEM;
   }else{
     rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
+    if( rc!=SQLITE_OK ){
+      *pzErr = sqlite3_mprintf("%s", sqlite3_errmsg(db));
+    }
   }
   sqlite3_free(zSql);
 
   if( rc==SQLITE_OK ){
     const char **azCol;           /* Output array */
@@ -1279,11 +1283,11 @@
     zCompress = 0;
     zUncompress = 0;
     if( nCol==0 ){
       sqlite3_free((void*)aCol); 
       aCol = 0;
-      rc = fts3ContentColumns(db, argv[1], zContent, &aCol, &nCol, &nString);
+      rc = fts3ContentColumns(db, argv[1], zContent,&aCol,&nCol,&nString,pzErr);
 
       /* If a languageid= option was specified, remove the language id
       ** column from the aCol[] array. */ 
       if( rc==SQLITE_OK && zLanguageid ){
         int j;
@@ -2500,30 +2504,37 @@
 ** parameter bDescDoclist should be false. If they are sorted in ascending 
 ** order, it should be passed a non-zero value.
 **
 ** The right-hand input doclist is overwritten by this function.
 */
-static void fts3DoclistPhraseMerge(
+static int fts3DoclistPhraseMerge(
   int bDescDoclist,               /* True if arguments are desc */
   int nDist,                      /* Distance from left to right (1=adjacent) */
   char *aLeft, int nLeft,         /* Left doclist */
-  char *aRight, int *pnRight      /* IN/OUT: Right/output doclist */
+  char **paRight, int *pnRight    /* IN/OUT: Right/output doclist */
 ){
   sqlite3_int64 i1 = 0;
   sqlite3_int64 i2 = 0;
   sqlite3_int64 iPrev = 0;
+  char *aRight = *paRight;
   char *pEnd1 = &aLeft[nLeft];
   char *pEnd2 = &aRight[*pnRight];
   char *p1 = aLeft;
   char *p2 = aRight;
   char *p;
   int bFirstOut = 0;
-  char *aOut = aRight;
+  char *aOut;
 
   assert( nDist>0 );
-
+  if( bDescDoclist ){
+    aOut = sqlite3_malloc(*pnRight + FTS3_VARINT_MAX);
+    if( aOut==0 ) return SQLITE_NOMEM;
+  }else{
+    aOut = aRight;
+  }
   p = aOut;
+
   fts3GetDeltaVarint3(&p1, pEnd1, 0, &i1);
   fts3GetDeltaVarint3(&p2, pEnd2, 0, &i2);
 
   while( p1 && p2 ){
     sqlite3_int64 iDiff = DOCID_CMP(i1, i2);
@@ -2548,10 +2559,16 @@
       fts3GetDeltaVarint3(&p2, pEnd2, bDescDoclist, &i2);
     }
   }
 
   *pnRight = (int)(p - aOut);
+  if( bDescDoclist ){
+    sqlite3_free(aRight);
+    *paRight = aOut;
+  }
+
+  return SQLITE_OK;
 }
 
 /*
 ** Argument pList points to a position list nList bytes in size. This
 ** function checks to see if the position list contains any entries for
@@ -2672,12 +2689,26 @@
   char *aDoclist,                 /* Pointer to doclist */
   int nDoclist                    /* Size of aDoclist in bytes */
 ){
   if( pTS->aaOutput[0]==0 ){
     /* If this is the first term selected, copy the doclist to the output
-    ** buffer using memcpy(). */
-    pTS->aaOutput[0] = sqlite3_malloc(nDoclist);
+    ** buffer using memcpy(). 
+    **
+    ** Add FTS3_VARINT_MAX bytes of unused space to the end of the 
+    ** allocation. This is so as to ensure that the buffer is big enough
+    ** to hold the current doclist AND'd with any other doclist. If the
+    ** doclists are stored in order=ASC order, this padding would not be
+    ** required (since the size of [doclistA AND doclistB] is always less
+    ** than or equal to the size of [doclistA] in that case). But this is
+    ** not true for order=DESC. For example, a doclist containing (1, -1) 
+    ** may be smaller than (-1), as in the first example the -1 may be stored
+    ** as a single-byte delta, whereas in the second it must be stored as a
+    ** FTS3_VARINT_MAX byte varint.
+    **
+    ** Similar padding is added in the fts3DoclistOrMerge() function.
+    */
+    pTS->aaOutput[0] = sqlite3_malloc(nDoclist + FTS3_VARINT_MAX + 1);
     pTS->anOutput[0] = nDoclist;
     if( pTS->aaOutput[0] ){
       memcpy(pTS->aaOutput[0], aDoclist, nDoclist);
     }else{
       return SQLITE_NOMEM;
@@ -3929,18 +3960,21 @@
 ** It is merged into the main doclist stored in p->doclist.aAll/nAll.
 **
 ** This function assumes that pList points to a buffer allocated using
 ** sqlite3_malloc(). This function takes responsibility for eventually
 ** freeing the buffer.
+**
+** SQLITE_OK is returned if successful, or SQLITE_NOMEM if an error occurs.
 */
-static void fts3EvalPhraseMergeToken(
+static int fts3EvalPhraseMergeToken(
   Fts3Table *pTab,                /* FTS Table pointer */
   Fts3Phrase *p,                  /* Phrase to merge pList/nList into */
   int iToken,                     /* Token pList/nList corresponds to */
   char *pList,                    /* Pointer to doclist */
   int nList                       /* Number of bytes in pList */
 ){
+  int rc = SQLITE_OK;
   assert( iToken!=p->iDoclistToken );
 
   if( pList==0 ){
     sqlite3_free(p->doclist.aAll);
     p->doclist.aAll = 0;
@@ -3975,17 +4009,20 @@
       pLeft = pList;
       nLeft = nList;
       nDiff = p->iDoclistToken - iToken;
     }
 
-    fts3DoclistPhraseMerge(pTab->bDescIdx, nDiff, pLeft, nLeft, pRight,&nRight);
+    rc = fts3DoclistPhraseMerge(
+        pTab->bDescIdx, nDiff, pLeft, nLeft, &pRight, &nRight
+    );
     sqlite3_free(pLeft);
     p->doclist.aAll = pRight;
     p->doclist.nAll = nRight;
   }
 
   if( iToken>p->iDoclistToken ) p->iDoclistToken = iToken;
+  return rc;
 }
 
 /*
 ** Load the doclist for phrase p into p->doclist.aAll/nAll. The loaded doclist
 ** does not take deferred tokens into account.
@@ -4007,11 +4044,11 @@
     if( pToken->pSegcsr ){
       int nThis = 0;
       char *pThis = 0;
       rc = fts3TermSelect(pTab, pToken, p->iColumn, &nThis, &pThis);
       if( rc==SQLITE_OK ){
-        fts3EvalPhraseMergeToken(pTab, p, iToken, pThis, nThis);
+        rc = fts3EvalPhraseMergeToken(pTab, p, iToken, pThis, nThis);
       }
     }
     assert( pToken->pSegcsr==0 );
   }
 
@@ -4809,13 +4846,17 @@
         Fts3PhraseToken *pToken = pTC->pToken;
         int nList = 0;
         char *pList = 0;
         rc = fts3TermSelect(pTab, pToken, pTC->iCol, &nList, &pList);
         assert( rc==SQLITE_OK || pList==0 );
+        if( rc==SQLITE_OK ){
+          rc = fts3EvalPhraseMergeToken(
+              pTab, pTC->pPhrase, pTC->iToken,pList,nList
+          );
+        }
         if( rc==SQLITE_OK ){
           int nCount;
-          fts3EvalPhraseMergeToken(pTab, pTC->pPhrase, pTC->iToken,pList,nList);
           nCount = fts3DoclistCountDocids(
               pTC->pPhrase->doclist.aAll, pTC->pPhrase->doclist.nAll
           );
           if( ii==0 || nCount<nMinEst ) nMinEst = nCount;
         }

Index: main.mk
==================================================================
--- main.mk
+++ main.mk
@@ -401,10 +401,14 @@
 
 sqlite3$(EXE):	$(TOP)/src/shell.c libsqlite3.a sqlite3.h
 	$(TCCX) $(READLINE_FLAGS) -o sqlite3$(EXE)                  \
 		$(TOP)/src/shell.c                                  \
 		libsqlite3.a $(LIBREADLINE) $(TLIBS) $(THREADLIB)
+
+sqldiff$(EXE):	$(TOP)/tool/sqldiff.c sqlite3.c sqlite3.h
+	$(TCCX) -o sqldiff$(EXE) -DSQLITE_THREADSAFE=0 \
+		$(TOP)/tool/sqldiff.c	sqlite3.c $(TLIBS) $(THREADLIB)
 
 mptester$(EXE):	sqlite3.c $(TOP)/mptest/mptest.c
 	$(TCCX) -o $@ -I. $(TOP)/mptest/mptest.c sqlite3.c \
 		$(TLIBS) $(THREADLIB)
 

Index: src/build.c
==================================================================
--- src/build.c
+++ src/build.c
@@ -3775,11 +3775,10 @@
 ** operator with A.  This routine shifts that operator over to B.
 */
 void sqlite3SrcListShiftJoinType(SrcList *p){
   if( p ){
     int i;
-    assert( p->a || p->nSrc==0 );
     for(i=p->nSrc-1; i>0; i--){
       p->a[i].jointype = p->a[i-1].jointype;
     }
     p->a[0].jointype = 0;
   }

Index: src/complete.c
==================================================================
--- src/complete.c
+++ src/complete.c
@@ -267,11 +267,11 @@
 ** UTF-8.
 */
 int sqlite3_complete16(const void *zSql){
   sqlite3_value *pVal;
   char const *zSql8;
-  int rc = SQLITE_NOMEM;
+  int rc;
 
 #ifndef SQLITE_OMIT_AUTOINIT
   rc = sqlite3_initialize();
   if( rc ) return rc;
 #endif

Index: src/os_unix.c
==================================================================
--- src/os_unix.c
+++ src/os_unix.c
@@ -3781,11 +3781,11 @@
 */
 static int unixFileControl(sqlite3_file *id, int op, void *pArg){
   unixFile *pFile = (unixFile*)id;
   switch( op ){
     case SQLITE_FCNTL_WAL_BLOCK: {
-      pFile->ctrlFlags |= UNIXFILE_BLOCK;
+      /* pFile->ctrlFlags |= UNIXFILE_BLOCK; // Deferred feature */
       return SQLITE_OK;
     }
     case SQLITE_FCNTL_LOCKSTATE: {
       *(int*)pArg = pFile->eFileLock;
       return SQLITE_OK;

Index: src/printf.c
==================================================================
--- src/printf.c
+++ src/printf.c
@@ -259,19 +259,23 @@
       }else{
         width = va_arg(ap,int);
       }
       if( width<0 ){
         flag_leftjustify = 1;
-        width = -width;
+        width = width >= -2147483647 ? -width : 0;
       }
       c = *++fmt;
     }else{
+      unsigned wx = 0;
       while( c>='0' && c<='9' ){
-        width = width*10 + c - '0';
+        wx = wx*10 + c - '0';
         c = *++fmt;
       }
+      testcase( wx>0x7fffffff );
+      width = wx & 0x7fffffff;
     }
+
     /* Get the precision */
     if( c=='.' ){
       precision = 0;
       c = *++fmt;
       if( c=='*' ){
@@ -278,17 +282,22 @@
         if( bArgList ){
           precision = (int)getIntArg(pArgList);
         }else{
           precision = va_arg(ap,int);
         }
-        if( precision<0 ) precision = -precision;
         c = *++fmt;
+        if( precision<0 ){
+          precision = precision >= -2147483647 ? -precision : -1;
+        }
       }else{
+        unsigned px = 0;
         while( c>='0' && c<='9' ){
-          precision = precision*10 + c - '0';
+          px = px*10 + c - '0';
           c = *++fmt;
         }
+        testcase( px>0x7fffffff );
+        precision = px & 0x7fffffff;
       }
     }else{
       precision = -1;
     }
     /* Get the conversion type modifier */
@@ -448,11 +457,12 @@
           if( flag_plussign )          prefix = '+';
           else if( flag_blanksign )    prefix = ' ';
           else                         prefix = 0;
         }
         if( xtype==etGENERIC && precision>0 ) precision--;
-        for(idx=precision, rounder=0.5; idx>0; idx--, rounder*=0.1){}
+        testcase( precision>0xfff );
+        for(idx=precision&0xfff, rounder=0.5; idx>0; idx--, rounder*=0.1){}
         if( xtype==etFLOAT ) realvalue += rounder;
         /* Normalize realvalue to within 10.0 > realvalue >= 1.0 */
         exp = 0;
         if( sqlite3IsNaN((double)realvalue) ){
           bufpt = "NaN";
@@ -503,12 +513,13 @@
         if( xtype==etEXP ){
           e2 = 0;
         }else{
           e2 = exp;
         }
-        if( MAX(e2,0)+precision+width > etBUFSIZE - 15 ){
-          bufpt = zExtra = sqlite3Malloc( MAX(e2,0)+precision+width+15 );
+        if( MAX(e2,0)+(i64)precision+(i64)width > etBUFSIZE - 15 ){
+          bufpt = zExtra 
+              = sqlite3Malloc( MAX(e2,0)+(i64)precision+(i64)width+15 );
           if( bufpt==0 ){
             setStrAccumError(pAccum, STRACCUM_NOMEM);
             return;
           }
         }
@@ -736,11 +747,11 @@
 ** Return the number of bytes of text that StrAccum is able to accept
 ** after the attempted enlargement.  The value returned might be zero.
 */
 static int sqlite3StrAccumEnlarge(StrAccum *p, int N){
   char *zNew;
-  assert( p->nChar+N >= p->nAlloc ); /* Only called if really needed */
+  assert( p->nChar+(i64)N >= p->nAlloc ); /* Only called if really needed */
   if( p->accError ){
     testcase(p->accError==STRACCUM_TOOBIG);
     testcase(p->accError==STRACCUM_NOMEM);
     return 0;
   }
@@ -785,11 +796,14 @@
 
 /*
 ** Append N copies of character c to the given string buffer.
 */
 void sqlite3AppendChar(StrAccum *p, int N, char c){
-  if( p->nChar+N >= p->nAlloc && (N = sqlite3StrAccumEnlarge(p, N))<=0 ) return;
+  testcase( p->nChar + (i64)N > 0x7fffffff );
+  if( p->nChar+(i64)N >= p->nAlloc && (N = sqlite3StrAccumEnlarge(p, N))<=0 ){
+    return;
+  }
   while( (N--)>0 ) p->zText[p->nChar++] = c;
 }
 
 /*
 ** The StrAccum "p" is not large enough to accept N new bytes of z[].

Index: src/resolve.c
==================================================================
--- src/resolve.c
+++ src/resolve.c
@@ -1184,10 +1184,24 @@
     sNC.pParse = pParse;
     if( sqlite3ResolveExprNames(&sNC, p->pLimit) ||
         sqlite3ResolveExprNames(&sNC, p->pOffset) ){
       return WRC_Abort;
     }
+
+    /* If the SF_Converted flags is set, then this Select object was
+    ** was created by the convertCompoundSelectToSubquery() function.
+    ** In this case the ORDER BY clause (p->pOrderBy) should be resolved
+    ** as if it were part of the sub-query, not the parent. This block
+    ** moves the pOrderBy down to the sub-query. It will be moved back
+    ** after the names have been resolved.  */
+    if( p->selFlags & SF_Converted ){
+      Select *pSub = p->pSrc->a[0].pSelect;
+      assert( p->pSrc->nSrc==1 && isCompound==0 && p->pOrderBy );
+      assert( pSub->pPrior && pSub->pOrderBy==0 );
+      pSub->pOrderBy = p->pOrderBy;
+      p->pOrderBy = 0;
+    }
   
     /* Recursively resolve names in all subqueries
     */
     for(i=0; i<p->pSrc->nSrc; i++){
       struct SrcList_item *pItem = &p->pSrc->a[i];
@@ -1265,10 +1279,21 @@
     /* The ORDER BY and GROUP BY clauses may not refer to terms in
     ** outer queries 
     */
     sNC.pNext = 0;
     sNC.ncFlags |= NC_AllowAgg;
+
+    /* If this is a converted compound query, move the ORDER BY clause from 
+    ** the sub-query back to the parent query. At this point each term
+    ** within the ORDER BY clause has been transformed to an integer value.
+    ** These integers will be replaced by copies of the corresponding result
+    ** set expressions by the call to resolveOrderGroupBy() below.  */
+    if( p->selFlags & SF_Converted ){
+      Select *pSub = p->pSrc->a[0].pSelect;
+      p->pOrderBy = pSub->pOrderBy;
+      pSub->pOrderBy = 0;
+    }
 
     /* Process the ORDER BY clause for singleton SELECT statements.
     ** The ORDER BY clause for compounds SELECT statements is handled
     ** below, after all of the result-sets for all of the elements of
     ** the compound have been resolved.

Index: src/select.c
==================================================================
--- src/select.c
+++ src/select.c
@@ -3882,10 +3882,12 @@
   pNew->pHaving = 0;
   pNew->pOrderBy = 0;
   p->pPrior = 0;
   p->pNext = 0;
   p->selFlags &= ~SF_Compound;
+  assert( (p->selFlags & SF_Converted)==0 );
+  p->selFlags |= SF_Converted;
   assert( pNew->pPrior!=0 );
   pNew->pPrior->pNext = pNew;
   pNew->pLimit = 0;
   pNew->pOffset = 0;
   return WRC_Continue;

Index: src/sqliteInt.h
==================================================================
--- src/sqliteInt.h
+++ src/sqliteInt.h
@@ -2388,10 +2388,11 @@
 #define SF_AllValues       0x0100  /* All terms of compound are VALUES */
 #define SF_NestedFrom      0x0200  /* Part of a parenthesized FROM clause */
 #define SF_MaybeConvert    0x0400  /* Need convertCompoundSelectToSubquery() */
 #define SF_Recursive       0x0800  /* The recursive part of a recursive CTE */
 #define SF_MinMaxAgg       0x1000  /* Aggregate containing min() or max() */
+#define SF_Converted       0x2000  /* By convertCompoundSelectToSubquery() */
 
 
 /*
 ** The results of a SELECT can be distributed in several ways, as defined
 ** by one of the following macros.  The "SRT" prefix means "SELECT Result

Index: src/trigger.c
==================================================================
--- src/trigger.c
+++ src/trigger.c
@@ -678,11 +678,10 @@
   SrcList *pSrc;       /* SrcList to be returned */
 
   pSrc = sqlite3SrcListAppend(pParse->db, 0, &pStep->target, 0);
   if( pSrc ){
     assert( pSrc->nSrc>0 );
-    assert( pSrc->a!=0 );
     iDb = sqlite3SchemaToIndex(pParse->db, pStep->pTrig->pSchema);
     if( iDb==0 || iDb>=2 ){
       sqlite3 *db = pParse->db;
       assert( iDb<pParse->db->nDb );
       pSrc->a[pSrc->nSrc-1].zDatabase = sqlite3DbStrDup(db, db->aDb[iDb].zName);

Index: src/vtab.c
==================================================================
--- src/vtab.c
+++ src/vtab.c
@@ -22,10 +22,12 @@
 ** are invoked only from within xCreate and xConnect methods.
 */
 struct VtabCtx {
   VTable *pVTable;    /* The virtual table being constructed */
   Table *pTab;        /* The Table object to which the virtual table belongs */
+  VtabCtx *pPrior;    /* Parent context (if any) */
+  int bDeclared;      /* True after sqlite3_declare_vtab() is called */
 };
 
 /*
 ** The actual function that does the work of creating a new module.
 ** This function implements the sqlite3_create_module() and
@@ -485,19 +487,31 @@
   Table *pTab,
   Module *pMod,
   int (*xConstruct)(sqlite3*,void*,int,const char*const*,sqlite3_vtab**,char**),
   char **pzErr
 ){
-  VtabCtx sCtx, *pPriorCtx;
+  VtabCtx sCtx;
   VTable *pVTable;
   int rc;
   const char *const*azArg = (const char *const*)pTab->azModuleArg;
   int nArg = pTab->nModuleArg;
   char *zErr = 0;
-  char *zModuleName = sqlite3MPrintf(db, "%s", pTab->zName);
+  char *zModuleName;
   int iDb;
+  VtabCtx *pCtx;
 
+  /* Check that the virtual-table is not already being initialized */
+  for(pCtx=db->pVtabCtx; pCtx; pCtx=pCtx->pPrior){
+    if( pCtx->pTab==pTab ){
+      *pzErr = sqlite3MPrintf(db, 
+          "vtable constructor called recursively: %s", pTab->zName
+      );
+      return SQLITE_LOCKED;
+    }
+  }
+
+  zModuleName = sqlite3MPrintf(db, "%s", pTab->zName);
   if( !zModuleName ){
     return SQLITE_NOMEM;
   }
 
   pVTable = sqlite3DbMallocZero(db, sizeof(VTable));
@@ -514,15 +528,17 @@
   /* Invoke the virtual table constructor */
   assert( &db->pVtabCtx );
   assert( xConstruct );
   sCtx.pTab = pTab;
   sCtx.pVTable = pVTable;
-  pPriorCtx = db->pVtabCtx;
+  sCtx.pPrior = db->pVtabCtx;
+  sCtx.bDeclared = 0;
   db->pVtabCtx = &sCtx;
   rc = xConstruct(db, pMod->pAux, nArg, azArg, &pVTable->pVtab, &zErr);
-  db->pVtabCtx = pPriorCtx;
+  db->pVtabCtx = sCtx.pPrior;
   if( rc==SQLITE_NOMEM ) db->mallocFailed = 1;
+  assert( sCtx.pTab==pTab );
 
   if( SQLITE_OK!=rc ){
     if( zErr==0 ){
       *pzErr = sqlite3MPrintf(db, "vtable constructor failed: %s", zModuleName);
     }else {
@@ -534,11 +550,11 @@
     /* Justification of ALWAYS():  A correct vtab constructor must allocate
     ** the sqlite3_vtab object if successful.  */
     memset(pVTable->pVtab, 0, sizeof(pVTable->pVtab[0]));
     pVTable->pVtab->pModule = pMod->pModule;
     pVTable->nRef = 1;
-    if( sCtx.pTab ){
+    if( sCtx.bDeclared==0 ){
       const char *zFormat = "vtable constructor did not declare schema: %s";
       *pzErr = sqlite3MPrintf(db, zFormat, pTab->zName);
       sqlite3VtabUnlock(pVTable);
       rc = SQLITE_ERROR;
     }else{
@@ -704,12 +720,12 @@
 ** This function is used to set the schema of a virtual table.  It is only
 ** valid to call this function from within the xCreate() or xConnect() of a
 ** virtual table module.
 */
 int sqlite3_declare_vtab(sqlite3 *db, const char *zCreateTable){
+  VtabCtx *pCtx = db->pVtabCtx;
   Parse *pParse;
-
   int rc = SQLITE_OK;
   Table *pTab;
   char *zErr = 0;
 
 #ifdef SQLITE_ENABLE_API_ARMOR
@@ -716,15 +732,16 @@
   if( !sqlite3SafetyCheckOk(db) || zCreateTable==0 ){
     return SQLITE_MISUSE_BKPT;
   }
 #endif
   sqlite3_mutex_enter(db->mutex);
-  if( !db->pVtabCtx || !(pTab = db->pVtabCtx->pTab) ){
+  if( !pCtx || pCtx->bDeclared ){
     sqlite3Error(db, SQLITE_MISUSE);
     sqlite3_mutex_leave(db->mutex);
     return SQLITE_MISUSE_BKPT;
   }
+  pTab = pCtx->pTab;
   assert( (pTab->tabFlags & TF_Virtual)!=0 );
 
   pParse = sqlite3StackAllocZero(db, sizeof(*pParse));
   if( pParse==0 ){
     rc = SQLITE_NOMEM;
@@ -743,11 +760,11 @@
         pTab->aCol = pParse->pNewTable->aCol;
         pTab->nCol = pParse->pNewTable->nCol;
         pParse->pNewTable->nCol = 0;
         pParse->pNewTable->aCol = 0;
       }
-      db->pVtabCtx->pTab = 0;
+      pCtx->bDeclared = 1;
     }else{
       sqlite3ErrorWithMsg(db, SQLITE_ERROR, (zErr ? "%s" : 0), zErr);
       sqlite3DbFree(db, zErr);
       rc = SQLITE_ERROR;
     }

Index: test/e_walauto.test
==================================================================
--- test/e_walauto.test
+++ test/e_walauto.test
@@ -13,10 +13,18 @@
 set testdir [file dirname $argv0]
 source $testdir/tester.tcl
 source $testdir/wal_common.tcl
 set testprefix e_walauto
 
+# Do not run this test on OpenBSD, as it depends on read() and mmap both
+# accessing the same coherent view of the "test.db-shm" file. This doesn't
+# work on OpenBSD.
+#
+if {$tcl_platform(os) == "OpenBSD"} {
+  finish_test
+  return
+}
 
 proc read_nbackfill {} {
   seek $::shmfd 96
   binary scan [read $::shmfd 4] n nBackfill
   set nBackfill

Index: test/fts3fault2.test
==================================================================
--- test/fts3fault2.test
+++ test/fts3fault2.test
@@ -152,7 +152,26 @@
     execsql { SELECT docid FROM ft WHERE ft MATCH 'th*' }
   } -test {
     faultsim_test_result {0 {1 2}}
   }
 }
+
+reset_db
+do_test 6.0 {
+  execsql {
+    CREATE VIRTUAL TABLE t6 USING fts4(x,order=DESC);
+    INSERT INTO t6(docid, x) VALUES(-1,'a b');
+    INSERT INTO t6(docid, x) VALUES(1, 'b');
+  }
+  faultsim_save_and_close
+} {}
+
+do_faultsim_test 6.1 -faults oom* -prep {
+  faultsim_restore_and_reopen
+  db eval {SELECT * FROM sqlite_master}
+} -body {
+  execsql { SELECT docid FROM t6 WHERE t6 MATCH '"a* b"' }
+} -test {
+  faultsim_test_result {0 -1}
+}
 
 finish_test

Index: test/fts3prefix.test
==================================================================
--- test/fts3prefix.test
+++ test/fts3prefix.test
@@ -271,7 +271,25 @@
   INSERT INTO t2 VALUES('He dressed himself in cycling clothes');
 } {}
 do_execsql_test 6.5.2 {
   SELECT md5sum(quote(root)) FROM t1_segdir;
 } [db eval {SELECT md5sum(quote(root)) FROM t2_segdir}]
+
+
+do_execsql_test 7.0 {
+  CREATE VIRTUAL TABLE t6 USING fts4(x,order=DESC);
+  INSERT INTO t6(docid, x) VALUES(-1,'a b');
+  INSERT INTO t6(docid, x) VALUES(1, 'b');
+}
+do_execsql_test 7.1 {
+  SELECT docid FROM t6 WHERE t6 MATCH '"a* b"';
+} {-1}
+do_execsql_test 7.2 {
+  SELECT docid FROM t6 WHERE t6 MATCH 'a*';
+} {-1}
+do_execsql_test 7.3 {
+  SELECT docid FROM t6 WHERE t6 MATCH 'a* b';
+} {-1}
+
+
 
 finish_test

Index: test/fts4content.test
==================================================================
--- test/fts4content.test
+++ test/fts4content.test
@@ -46,10 +46,13 @@
 #   8.* - Test that if the content=xxx and prefix options are used together,
 #         the 'rebuild' command still works.
 #
 #   9.* - Test using content=xxx where xxx is a virtual table.
 #
+#   11.* - Test that circular references (e.g. "t1(content=t1)") are
+#          detected.
+#
 
 do_execsql_test 1.1.1 {
   CREATE TABLE t1(a, b, c);
   INSERT INTO t1 VALUES('w x', 'x y', 'y z');
   CREATE VIRTUAL TABLE ft1 USING fts4(content=t1);
@@ -404,11 +407,11 @@
 #-------------------------------------------------------------------------
 # Test cases 6.* test 
 # 
 do_catchsql_test 6.1.1 {
   CREATE VIRTUAL TABLE ft7 USING fts4(content=t7);
-} {1 {vtable constructor failed: ft7}}
+} {1 {no such table: main.t7}}
 
 do_execsql_test 6.2.1 {
   CREATE TABLE t7(one, two);
   CREATE VIRTUAL TABLE ft7 USING fts4(content=t7);
   INSERT INTO t7 VALUES('A B', 'B A');
@@ -431,11 +434,11 @@
   ft7 ft7_segments ft7_segdir sqlite_autoindex_ft7_segdir_1 
   ft7_docsize ft7_stat
 }
 do_catchsql_test 6.2.4 {
   SELECT * FROM ft7;
-} {1 {vtable constructor failed: ft7}}
+} {1 {no such table: main.t7}}
 do_execsql_test 6.2.5 {
   CREATE TABLE t7(x, y);
   INSERT INTO t7 VALUES('A B', 'B A');
   INSERT INTO t7 VALUES('C D', 'A A');
   SELECT * FROM ft7;
@@ -619,7 +622,18 @@
 do_execsql_test 10.7 {
   SELECT snippet(ft, '[', ']', '...', -1, 5) FROM ft WHERE ft MATCH 'e'
 } {
   {...c d [e] f g...}
 }
+
+#-------------------------------------------------------------------------
+# Test cases 11.*
+# 
+reset_db
+
+do_catchsql_test 11.1 {
+  CREATE VIRTUAL TABLE x1 USING fts4(content=x1);
+} {1 {vtable constructor called recursively: x1}}
+
 
 finish_test
+

Index: test/printf.test
==================================================================
--- test/printf.test
+++ test/printf.test
@@ -470,10 +470,22 @@
 } {abc: (-9999999) (ff676981) (37731664601) :xyz}
 do_test printf-1.16.7 {
   sqlite3_mprintf_int {abc: (%#6d) (%#6x) (%#6o) :xyz}\
        0xff676981 0xff676981 0xff676981
 } {abc: (-9999999) (0xff676981) (037731664601) :xyz}
+do_test printf-1.17.1 {
+  sqlite3_mprintf_int {abd: %2147483647d %2147483647x %2147483647o} 1 1 1
+} {}
+do_test printf-1.17.2 {
+  sqlite3_mprintf_int {abd: %*d %x} 2147483647 1 1
+} {}
+do_test printf-1.17.3 {
+  sqlite3_mprintf_int {abd: %*d %x} -2147483648 1 1
+} {abd: 1 1}
+do_test printf-1.17.4 {
+  sqlite3_mprintf_int {abd: %.2147483648d %x %x} 1 1 1
+} {/.*/}
 do_test printf-2.1.1.1 {
   sqlite3_mprintf_double {abc: (%*.*f) :xyz} 1 1 0.001
 } {abc: (0.0) :xyz}
 do_test printf-2.1.1.2 {
   sqlite3_mprintf_double {abc: (%*.*e) :xyz} 1 1 0.001
@@ -524,10 +536,13 @@
   sqlite3_mprintf_double {abc: %d %d (%1.1e) :xyz} 1 1 1.0e-20
 } {abc: 1 1 (1.0e-20) :xyz}
 do_test printf-2.1.2.9 {
   sqlite3_mprintf_double {abc: %d %d (%1.1g) :xyz} 1 1 1.0e-20
 } {abc: 1 1 (1e-20) :xyz}
+do_test printf-2.1.2.10 {
+  sqlite3_mprintf_double {abc: %*.*f}  2000000000 1000000000 1.0e-20
+} {abc: }
 do_test printf-2.1.3.1 {
   sqlite3_mprintf_double {abc: (%*.*f) :xyz} 1 1 1.0
 } {abc: (1.0) :xyz}
 do_test printf-2.1.3.2 {
   sqlite3_mprintf_double {abc: (%*.*e) :xyz} 1 1 1.0
@@ -3464,10 +3479,19 @@
   sqlite3_mprintf_str {%d %d A String: (%30s)} 1 2 {This is the string}
 } [format {%d %d A String: (%30s)} 1 2 {This is the string}]
 do_test printf-3.6 {
   sqlite3_mprintf_str {%d %d A String: (%-30s)} 1 2 {This is the string}
 } [format {%d %d A String: (%-30s)} 1 2 {This is the string}]
+do_test printf-3.7 {
+  sqlite3_mprintf_str {%d A String: (%*s)} 1 2147483647 {This is the string}
+} []
+do_test printf-3.8 {
+  sqlite3_mprintf_str {%d A String: (%*s)} 1 -2147483648 {This is the string}
+} {1 A String: (This is the string)}
+do_test printf-3.9 {
+  sqlite3_mprintf_str {%d A String: (%.*s)} 1 -2147483648 {This is the string}
+} {1 A String: (This is the string)}
 do_test snprintf-3.11 {
   sqlite3_snprintf_str 2 {x%d %d %s} 10 10 {This is the string}
 } {x}
 do_test snprintf-3.12 {
   sqlite3_snprintf_str 3 {x%d %d %s} 10 10 {This is the string}
@@ -3683,10 +3707,13 @@
   sqlite3_mprintf_hexdouble %.20f fff0000000000000
 } {-Inf}
 do_test printf-13.6 {
   sqlite3_mprintf_hexdouble %.20f fff8000000000000
 } {NaN}
+do_test printf-13.7 {
+  sqlite3_mprintf_hexdouble %2147483648.10000f 4693b8b5b5056e17
+} {/100000000000000000000000000000000.00/}
 
 do_test printf-14.1 {
   sqlite3_mprintf_str {abc-%y-123} 0 0 {not used}
 } {abc-}
 do_test printf-14.2 {

Index: test/selectA.test
==================================================================
--- test/selectA.test
+++ test/selectA.test
@@ -1372,7 +1372,67 @@
   UNION ALL
   SELECT a, b FROM t6 
   ORDER BY 1,2
 } {/2 . 3 . 4 . 5 . 6 . 7 ./}
 
+
+proc strip_rnd {explain} {
+  regexp -all {sqlite_sq_[0123456789ABCDEF]*} $explain sqlite_sq
+}
+
+proc do_same_test {tn q1 args} {
+  set r2 [strip_rnd [db eval "EXPLAIN $q1"]]
+  set i 1
+  foreach q $args {
+    set tst [subst -nocommands {strip_rnd [db eval "EXPLAIN $q"]}]
+    uplevel do_test $tn.$i [list $tst] [list $r2]
+    incr i
+  }
+}
+
+do_execsql_test 5.0 {
+  CREATE TABLE t8(a, b);
+  CREATE TABLE t9(c, d);
+} {}
+
+do_same_test 5.1 {
+  SELECT a, b FROM t8 INTERSECT SELECT c, d FROM t9 ORDER BY a;
+} {
+  SELECT a, b FROM t8 INTERSECT SELECT c, d FROM t9 ORDER BY t8.a;
+} {
+  SELECT a, b FROM t8 INTERSECT SELECT c, d FROM t9 ORDER BY 1;
+} {
+  SELECT a, b FROM t8 INTERSECT SELECT c, d FROM t9 ORDER BY c;
+} {
+  SELECT a, b FROM t8 INTERSECT SELECT c, d FROM t9 ORDER BY t9.c;
+}
+
+do_same_test 5.2 {
+  SELECT a, b FROM t8 UNION SELECT c, d FROM t9 ORDER BY a COLLATE NOCASE
+} {
+  SELECT a, b FROM t8 UNION SELECT c, d FROM t9 ORDER BY t8.a COLLATE NOCASE
+} {
+  SELECT a, b FROM t8 UNION SELECT c, d FROM t9 ORDER BY 1 COLLATE NOCASE
+} {
+  SELECT a, b FROM t8 UNION SELECT c, d FROM t9 ORDER BY c COLLATE NOCASE
+} {
+  SELECT a, b FROM t8 UNION SELECT c, d FROM t9 ORDER BY t9.c COLLATE NOCASE
+}
+
+do_same_test 5.3 {
+  SELECT a, b FROM t8 EXCEPT SELECT c, d FROM t9 ORDER BY b, c COLLATE NOCASE
+} {
+  SELECT a, b FROM t8 EXCEPT SELECT c, d FROM t9 ORDER BY 2, 1 COLLATE NOCASE
+} {
+  SELECT a, b FROM t8 EXCEPT SELECT c, d FROM t9 ORDER BY d, a COLLATE NOCASE
+} {
+  SELECT a, b FROM t8 EXCEPT SELECT * FROM t9 ORDER BY t9.d, c COLLATE NOCASE
+} {
+  SELECT * FROM t8 EXCEPT SELECT c, d FROM t9 ORDER BY d, t8.a COLLATE NOCASE
+}
+
+do_catchsql_test 5.4 {
+  SELECT * FROM t8 UNION SELECT * FROM t9 ORDER BY a+b COLLATE NOCASE
+} {1 {1st ORDER BY term does not match any column in the result set}}
+
 
 finish_test

Index: test/walblock.test
==================================================================
--- test/walblock.test
+++ test/walblock.test
@@ -13,10 +13,11 @@
 set testdir [file dirname $argv0]
 source $testdir/tester.tcl
 source $testdir/lock_common.tcl
 source $testdir/wal_common.tcl
 
+finish_test; return;    #  Feature currently not implemented.
 ifcapable !wal {finish_test ; return }
 if {$::tcl_platform(platform)!="unix"} { finish_test ; return }
 set testprefix walblock
 
 catch { db close }
@@ -109,9 +110,5 @@
   set ::out 
 } {1 2 3 4 5 6 7 8 9 10}
 
 
 finish_test
-
-
-
-

ADDED   tool/showlocks.c
Index: tool/showlocks.c
==================================================================
--- tool/showlocks.c
+++ tool/showlocks.c
@@ -0,0 +1,64 @@
+/*
+** This file implements a simple command-line utility that shows all of the
+** Posix Advisory Locks on a file.
+**
+** Usage:
+**
+**     showlocks FILENAME
+**
+** To compile:  gcc -o showlocks showlocks.c
+*/
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* This utility only looks for locks in the first 2 billion bytes */
+#define MX_LCK 2147483647
+
+/*
+** Print all locks on the inode of "fd" that occur in between
+** lwr and upr, inclusive.
+*/
+static int showLocksInRange(int fd, off_t lwr, off_t upr){
+  int cnt = 0;
+  struct flock x;
+
+  x.l_type = F_WRLCK;
+  x.l_whence = SEEK_SET;
+  x.l_start = lwr;
+  x.l_len = upr-lwr;
+  fcntl(fd, F_GETLK, &x);
+  if( x.l_type==F_UNLCK ) return 0;
+  printf("start: %-12d len: %-5d pid: %-5d type: %s\n",
+       (int)x.l_start, (int)x.l_len,
+       x.l_pid, x.l_type==F_WRLCK ? "WRLCK" : "RDLCK");
+  cnt++;
+  if( x.l_start>lwr ){
+    cnt += showLocksInRange(fd, lwr, x.l_start-1);
+  }
+  if( x.l_start+x.l_len<upr ){
+    cnt += showLocksInRange(fd, x.l_start+x.l_len+1, upr);
+  }
+  return cnt;
+}
+
+int main(int argc, char **argv){
+  int fd;
+  int cnt;
+
+  if( argc!=2 ){
+    fprintf(stderr, "Usage: %s FILENAME\n", argv[0]);
+    return 1;
+  }
+  fd = open(argv[1], O_RDWR, 0);
+  if( fd<0 ){
+    fprintf(stderr, "%s: cannot open %s\n", argv[0], argv[1]);
+    return 1;
+  }
+  cnt = showLocksInRange(fd, 0, MX_LCK);
+  if( cnt==0 ) printf("no locks\n");  
+  close(fd);
+  return 0;
+}

ADDED   tool/sqldiff.c
Index: tool/sqldiff.c
==================================================================
--- tool/sqldiff.c
+++ tool/sqldiff.c
@@ -0,0 +1,817 @@
+/*
+** 2015-04-06
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This is a utility problem that computes the differences in content
+** between two SQLite databases.
+*/
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <ctype.h>
+#include <string.h>
+#include "sqlite3.h"
+
+/*
+** All global variables are gathered into the "g" singleton.
+*/
+struct GlobalVars {
+  const char *zArgv0;       /* Name of program */
+  int bSchemaOnly;          /* Only show schema differences */
+  int bSchemaPK;            /* Use the schema-defined PK, not the true PK */
+  unsigned fDebug;          /* Debug flags */
+  sqlite3 *db;              /* The database connection */
+} g;
+
+/*
+** Allowed values for g.fDebug
+*/
+#define DEBUG_COLUMN_NAMES  0x000001
+#define DEBUG_DIFF_SQL      0x000002
+
+/*
+** Dynamic string object
+*/
+typedef struct Str Str;
+struct Str {
+  char *z;        /* Text of the string */
+  int nAlloc;     /* Bytes allocated in z[] */
+  int nUsed;      /* Bytes actually used in z[] */
+};
+
+/*
+** Initialize a Str object
+*/
+static void strInit(Str *p){
+  p->z = 0;
+  p->nAlloc = 0;
+  p->nUsed = 0;
+}
+  
+/*
+** Print an error resulting from faulting command-line arguments and
+** abort the program.
+*/
+static void cmdlineError(const char *zFormat, ...){
+  va_list ap;
+  fprintf(stderr, "%s: ", g.zArgv0);
+  va_start(ap, zFormat);
+  vfprintf(stderr, zFormat, ap);
+  va_end(ap);
+  fprintf(stderr, "\n\"%s --help\" for more help\n", g.zArgv0);
+  exit(1);
+}
+
+/*
+** Print an error message for an error that occurs at runtime, then
+** abort the program.
+*/
+static void runtimeError(const char *zFormat, ...){
+  va_list ap;
+  fprintf(stderr, "%s: ", g.zArgv0);
+  va_start(ap, zFormat);
+  vfprintf(stderr, zFormat, ap);
+  va_end(ap);
+  fprintf(stderr, "\n");
+  exit(1);
+}
+
+/*
+** Free all memory held by a Str object
+*/
+static void strFree(Str *p){
+  sqlite3_free(p->z);
+  strInit(p);
+}
+
+/*
+** Add formatted text to the end of a Str object
+*/
+static void strPrintf(Str *p, const char *zFormat, ...){
+  int nNew;
+  for(;;){
+    if( p->z ){
+      va_list ap;
+      va_start(ap, zFormat);
+      sqlite3_vsnprintf(p->nAlloc-p->nUsed, p->z+p->nUsed, zFormat, ap);
+      va_end(ap);
+      nNew = (int)strlen(p->z + p->nUsed);
+    }else{
+      nNew = p->nAlloc;
+    }
+    if( p->nUsed+nNew < p->nAlloc-1 ){
+      p->nUsed += nNew;
+      break;
+    }
+    p->nAlloc = p->nAlloc*2 + 1000;
+    p->z = sqlite3_realloc(p->z, p->nAlloc);
+    if( p->z==0 ) runtimeError("out of memory");
+  }
+}
+
+
+
+/* Safely quote an SQL identifier.  Use the minimum amount of transformation
+** necessary to allow the string to be used with %s.
+**
+** Space to hold the returned string is obtained from sqlite3_malloc().  The
+** caller is responsible for ensuring this space is freed when no longer
+** needed.
+*/
+static char *safeId(const char *zId){
+  /* All SQLite keywords, in alphabetical order */
+  static const char *azKeywords[] = {
+    "ABORT", "ACTION", "ADD", "AFTER", "ALL", "ALTER", "ANALYZE", "AND", "AS",
+    "ASC", "ATTACH", "AUTOINCREMENT", "BEFORE", "BEGIN", "BETWEEN", "BY",
+    "CASCADE", "CASE", "CAST", "CHECK", "COLLATE", "COLUMN", "COMMIT",
+    "CONFLICT", "CONSTRAINT", "CREATE", "CROSS", "CURRENT_DATE",
+    "CURRENT_TIME", "CURRENT_TIMESTAMP", "DATABASE", "DEFAULT", "DEFERRABLE",
+    "DEFERRED", "DELETE", "DESC", "DETACH", "DISTINCT", "DROP", "EACH",
+    "ELSE", "END", "ESCAPE", "EXCEPT", "EXCLUSIVE", "EXISTS", "EXPLAIN",
+    "FAIL", "FOR", "FOREIGN", "FROM", "FULL", "GLOB", "GROUP", "HAVING", "IF",
+    "IGNORE", "IMMEDIATE", "IN", "INDEX", "INDEXED", "INITIALLY", "INNER",
+    "INSERT", "INSTEAD", "INTERSECT", "INTO", "IS", "ISNULL", "JOIN", "KEY",
+    "LEFT", "LIKE", "LIMIT", "MATCH", "NATURAL", "NO", "NOT", "NOTNULL",
+    "NULL", "OF", "OFFSET", "ON", "OR", "ORDER", "OUTER", "PLAN", "PRAGMA",
+    "PRIMARY", "QUERY", "RAISE", "RECURSIVE", "REFERENCES", "REGEXP",
+    "REINDEX", "RELEASE", "RENAME", "REPLACE", "RESTRICT", "RIGHT",
+    "ROLLBACK", "ROW", "SAVEPOINT", "SELECT", "SET", "TABLE", "TEMP",
+    "TEMPORARY", "THEN", "TO", "TRANSACTION", "TRIGGER", "UNION", "UNIQUE",
+    "UPDATE", "USING", "VACUUM", "VALUES", "VIEW", "VIRTUAL", "WHEN", "WHERE",
+    "WITH", "WITHOUT",
+  };
+  int lwr, upr, mid, c, i, x;
+  for(i=x=0; (c = zId[i])!=0; i++){
+    if( !isalpha(c) && c!='_' ){
+      if( i>0 && isdigit(c) ){
+        x++;
+      }else{
+        return sqlite3_mprintf("\"%w\"", zId);
+      }
+    }
+  }
+  if( x ) return sqlite3_mprintf("%s", zId);
+  lwr = 0;
+  upr = sizeof(azKeywords)/sizeof(azKeywords[0]) - 1;
+  while( lwr<=upr ){
+    mid = (lwr+upr)/2;
+    c = sqlite3_stricmp(azKeywords[mid], zId);
+    if( c==0 ) return sqlite3_mprintf("\"%w\"", zId);
+    if( c<0 ){
+      lwr = mid+1;
+    }else{
+      upr = mid-1;
+    }
+  }
+  return sqlite3_mprintf("%s", zId);
+}
+
+/*
+** Prepare a new SQL statement.  Print an error and abort if anything
+** goes wrong.
+*/
+static sqlite3_stmt *db_vprepare(const char *zFormat, va_list ap){
+  char *zSql;
+  int rc;
+  sqlite3_stmt *pStmt;
+
+  zSql = sqlite3_vmprintf(zFormat, ap);
+  if( zSql==0 ) runtimeError("out of memory");
+  rc = sqlite3_prepare_v2(g.db, zSql, -1, &pStmt, 0);
+  if( rc ){
+    runtimeError("SQL statement error: %s\n\"%s\"", sqlite3_errmsg(g.db),
+                 zSql);
+  }
+  sqlite3_free(zSql);
+  return pStmt;
+}
+static sqlite3_stmt *db_prepare(const char *zFormat, ...){
+  va_list ap;
+  sqlite3_stmt *pStmt;
+  va_start(ap, zFormat);
+  pStmt = db_vprepare(zFormat, ap);
+  va_end(ap);
+  return pStmt;
+}
+
+/*
+** Free a list of strings
+*/
+static void namelistFree(char **az){
+  if( az ){
+    int i;
+    for(i=0; az[i]; i++) sqlite3_free(az[i]);
+    sqlite3_free(az);
+  }
+}
+
+/*
+** Return a list of column names for the table zDb.zTab.  Space to
+** hold the list is obtained from sqlite3_malloc() and should released
+** using namelistFree() when no longer needed.
+**
+** Primary key columns are listed first, followed by data columns.
+** The number of columns in the primary key is returned in *pnPkey.
+**
+** Normally, the "primary key" in the previous sentence is the true
+** primary key - the rowid or INTEGER PRIMARY KEY for ordinary tables
+** or the declared PRIMARY KEY for WITHOUT ROWID tables.  However, if
+** the g.bSchemaPK flag is set, then the schema-defined PRIMARY KEY is
+** used in all cases.  In that case, entries that have NULL values in
+** any of their primary key fields will be excluded from the analysis.
+**
+** If the primary key for a table is the rowid but rowid is inaccessible,
+** then this routine returns a NULL pointer.
+**
+** Examples:
+**    CREATE TABLE t1(a INT UNIQUE, b INTEGER, c TEXT, PRIMARY KEY(c));
+**    *pnPKey = 1;
+**    az = { "rowid", "a", "b", "c", 0 }  // Normal case
+**    az = { "c", "a", "b", 0 }           // g.bSchemaPK==1
+**
+**    CREATE TABLE t2(a INT UNIQUE, b INTEGER, c TEXT, PRIMARY KEY(b));
+**    *pnPKey = 1;
+**    az = { "b", "a", "c", 0 }
+**
+**    CREATE TABLE t3(x,y,z,PRIMARY KEY(y,z));
+**    *pnPKey = 1                         // Normal case
+**    az = { "rowid", "x", "y", "z", 0 }  // Normal case
+**    *pnPKey = 2                         // g.bSchemaPK==1
+**    az = { "y", "x", "z", 0 }           // g.bSchemaPK==1
+**
+**    CREATE TABLE t4(x,y,z,PRIMARY KEY(y,z)) WITHOUT ROWID;
+**    *pnPKey = 2
+**    az = { "y", "z", "x", 0 }
+**
+**    CREATE TABLE t5(rowid,_rowid_,oid);
+**    az = 0     // The rowid is not accessible
+*/
+static char **columnNames(const char *zDb, const char *zTab, int *pnPKey){
+  char **az = 0;           /* List of column names to be returned */
+  int naz = 0;             /* Number of entries in az[] */
+  sqlite3_stmt *pStmt;     /* SQL statement being run */
+  char *zPkIdxName = 0;    /* Name of the PRIMARY KEY index */
+  int truePk = 0;          /* PRAGMA table_info indentifies the PK to use */
+  int nPK = 0;             /* Number of PRIMARY KEY columns */
+  int i, j;                /* Loop counters */
+
+  if( g.bSchemaPK==0 ){
+    /* Normal case:  Figure out what the true primary key is for the table.
+    **   *  For WITHOUT ROWID tables, the true primary key is the same as
+    **      the schema PRIMARY KEY, which is guaranteed to be present.
+    **   *  For rowid tables with an INTEGER PRIMARY KEY, the true primary
+    **      key is the INTEGER PRIMARY KEY.
+    **   *  For all other rowid tables, the rowid is the true primary key.
+    */
+    pStmt = db_prepare("PRAGMA %s.index_list=%Q", zDb, zTab);
+    while( SQLITE_ROW==sqlite3_step(pStmt) ){
+      if( sqlite3_stricmp((const char*)sqlite3_column_text(pStmt,3),"pk")==0 ){
+        zPkIdxName = sqlite3_mprintf("%s", sqlite3_column_text(pStmt, 1));
+        break;
+      }
+    }
+    sqlite3_finalize(pStmt);
+    if( zPkIdxName ){
+      int nKey = 0;
+      int nCol = 0;
+      truePk = 0;
+      pStmt = db_prepare("PRAGMA %s.index_xinfo=%Q", zDb, zPkIdxName);
+      while( SQLITE_ROW==sqlite3_step(pStmt) ){
+        nCol++;
+        if( sqlite3_column_int(pStmt,5) ){ nKey++; continue; }
+        if( sqlite3_column_int(pStmt,1)>=0 ) truePk = 1;
+      }
+      if( nCol==nKey ) truePk = 1;
+      if( truePk ){
+        nPK = nKey;
+      }else{
+        nPK = 1;
+      }
+      sqlite3_finalize(pStmt);
+      sqlite3_free(zPkIdxName);
+    }else{
+      truePk = 1;
+      nPK = 1;
+    }
+    pStmt = db_prepare("PRAGMA %s.table_info=%Q", zDb, zTab);
+  }else{
+    /* The g.bSchemaPK==1 case:  Use whatever primary key is declared
+    ** in the schema.  The "rowid" will still be used as the primary key
+    ** if the table definition does not contain a PRIMARY KEY.
+    */
+    nPK = 0;
+    pStmt = db_prepare("PRAGMA %s.table_info=%Q", zDb, zTab);
+    while( SQLITE_ROW==sqlite3_step(pStmt) ){
+      if( sqlite3_column_int(pStmt,5)>0 ) nPK++;
+    }
+    sqlite3_reset(pStmt);
+    if( nPK==0 ) nPK = 1;
+    truePk = 1;
+  }
+  *pnPKey = nPK;
+  naz = nPK;
+  az = sqlite3_malloc( sizeof(char*)*(nPK+1) );
+  if( az==0 ) runtimeError("out of memory");
+  memset(az, 0, sizeof(char*)*(nPK+1));
+  while( SQLITE_ROW==sqlite3_step(pStmt) ){
+    int iPKey;
+    if( truePk && (iPKey = sqlite3_column_int(pStmt,5))>0 ){
+      az[iPKey-1] = safeId((char*)sqlite3_column_text(pStmt,1));
+    }else{
+      az = sqlite3_realloc(az, sizeof(char*)*(naz+2) );
+      if( az==0 ) runtimeError("out of memory");
+      az[naz++] = safeId((char*)sqlite3_column_text(pStmt,1));
+    }
+  }
+  sqlite3_finalize(pStmt);
+  if( az ) az[naz] = 0;
+  if( az[0]==0 ){
+    const char *azRowid[] = { "rowid", "_rowid_", "oid" };
+    for(i=0; i<sizeof(azRowid)/sizeof(azRowid[0]); i++){
+      for(j=1; j<naz; j++){
+        if( sqlite3_stricmp(az[j], azRowid[i])==0 ) break;
+      }
+      if( j>=naz ){
+        az[0] = sqlite3_mprintf("%s", azRowid[i]);
+        break;
+      }
+    }
+    if( az[0]==0 ){
+      for(i=1; i<naz; i++) sqlite3_free(az[i]);
+      sqlite3_free(az);
+      az = 0;
+    }
+  }
+  return az;
+}
+
+/*
+** Print the sqlite3_value X as an SQL literal.
+*/
+static void printQuoted(sqlite3_value *X){
+  switch( sqlite3_value_type(X) ){
+    case SQLITE_FLOAT: {
+      double r1;
+      char zBuf[50];
+      r1 = sqlite3_value_double(X);
+      sqlite3_snprintf(sizeof(zBuf), zBuf, "%!.15g", r1);
+      printf("%s", zBuf);
+      break;
+    }
+    case SQLITE_INTEGER: {
+      printf("%lld", sqlite3_value_int64(X));
+      break;
+    }
+    case SQLITE_BLOB: {
+      const unsigned char *zBlob = sqlite3_value_blob(X);
+      int nBlob = sqlite3_value_bytes(X);
+      if( zBlob ){
+        int i;
+        printf("x'");
+        for(i=0; i<nBlob; i++){
+          printf("%02x", zBlob[i]);
+        }
+        printf("'");
+      }else{
+        printf("NULL");
+      }
+      break;
+    }
+    case SQLITE_TEXT: {
+      const unsigned char *zArg = sqlite3_value_text(X);
+      int i, j;
+
+      if( zArg==0 ){
+        printf("NULL");
+      }else{
+        printf("'");
+        for(i=j=0; zArg[i]; i++){
+          if( zArg[i]=='\'' ){
+            printf("%.*s'", i-j+1, &zArg[j]);
+            j = i+1;
+          }
+        }
+        printf("%s'", &zArg[j]);
+      }
+      break;
+    }
+    case SQLITE_NULL: {
+      printf("NULL");
+      break;
+    }
+  }
+}
+
+/*
+** Output SQL that will recreate the aux.zTab table.
+*/
+static void dump_table(const char *zTab){
+  char *zId = safeId(zTab); /* Name of the table */
+  char **az = 0;            /* List of columns */
+  int nPk;                  /* Number of true primary key columns */
+  int nCol;                 /* Number of data columns */
+  int i;                    /* Loop counter */
+  sqlite3_stmt *pStmt;      /* SQL statement */
+  const char *zSep;         /* Separator string */
+  Str ins;                  /* Beginning of the INSERT statement */
+
+  pStmt = db_prepare("SELECT sql FROM aux.sqlite_master WHERE name=%Q", zTab);
+  if( SQLITE_ROW==sqlite3_step(pStmt) ){
+    printf("%s;\n", sqlite3_column_text(pStmt,0));
+  }
+  sqlite3_finalize(pStmt);
+  if( !g.bSchemaOnly ){
+    az = columnNames("aux", zTab, &nPk);
+    strInit(&ins);
+    if( az==0 ){
+      pStmt = db_prepare("SELECT * FROM aux.%s", zId);
+      strPrintf(&ins,"INSERT INTO %s VALUES", zId);
+    }else{
+      Str sql;
+      strInit(&sql);
+      zSep =  "SELECT";
+      for(i=0; az[i]; i++){
+        strPrintf(&sql, "%s %s", zSep, az[i]);
+        zSep = ",";
+      }
+      strPrintf(&sql," FROM aux.%s", zId);
+      zSep = " ORDER BY";
+      for(i=1; i<=nPk; i++){
+        strPrintf(&sql, "%s %d", zSep, i);
+        zSep = ",";
+      }
+      pStmt = db_prepare("%s", sql.z);
+      strFree(&sql);
+      strPrintf(&ins, "INSERT INTO %s", zId);
+      zSep = "(";
+      for(i=0; az[i]; i++){
+        strPrintf(&ins, "%s%s", zSep, az[i]);
+        zSep = ",";
+      }
+      strPrintf(&ins,") VALUES");
+      namelistFree(az);
+    }
+    nCol = sqlite3_column_count(pStmt);
+    while( SQLITE_ROW==sqlite3_step(pStmt) ){
+      printf("%s",ins.z);
+      zSep = "(";
+      for(i=0; i<nCol; i++){
+        printf("%s",zSep);
+        printQuoted(sqlite3_column_value(pStmt,i));
+        zSep = ",";
+      }
+      printf(");\n");
+    }
+    sqlite3_finalize(pStmt);
+    strFree(&ins);
+  } /* endif !g.bSchemaOnly */
+  pStmt = db_prepare("SELECT sql FROM aux.sqlite_master"
+                     " WHERE type='index' AND tbl_name=%Q AND sql IS NOT NULL",
+                     zTab);
+  while( SQLITE_ROW==sqlite3_step(pStmt) ){
+    printf("%s;\n", sqlite3_column_text(pStmt,0));
+  }
+  sqlite3_finalize(pStmt);
+}
+
+
+/*
+** Compute all differences for a single table.
+*/
+static void diff_one_table(const char *zTab){
+  char *zId = safeId(zTab); /* Name of table (translated for us in SQL) */
+  char **az = 0;            /* Columns in main */
+  char **az2 = 0;           /* Columns in aux */
+  int nPk;                  /* Primary key columns in main */
+  int nPk2;                 /* Primary key columns in aux */
+  int n;                    /* Number of columns in main */
+  int n2;                   /* Number of columns in aux */
+  int nQ;                   /* Number of output columns in the diff query */
+  int i;                    /* Loop counter */
+  const char *zSep;         /* Separator string */
+  Str sql;                  /* Comparison query */
+  sqlite3_stmt *pStmt;      /* Query statement to do the diff */
+
+  strInit(&sql);
+  if( g.fDebug==DEBUG_COLUMN_NAMES ){
+    /* Simply run columnNames() on all tables of the origin
+    ** database and show the results.  This is used for testing
+    ** and debugging of the columnNames() function.
+    */
+    az = columnNames("aux",zTab, &nPk);
+    if( az==0 ){
+      printf("Rowid not accessible for %s\n", zId);
+    }else{
+      printf("%s:", zId);
+      for(i=0; az[i]; i++){
+        printf(" %s", az[i]);
+        if( i+1==nPk ) printf(" *");
+      }
+      printf("\n");
+    }
+    goto end_diff_one_table;
+  }
+    
+
+  if( sqlite3_table_column_metadata(g.db,"aux",zTab,0,0,0,0,0,0) ){
+    if( !sqlite3_table_column_metadata(g.db,"main",zTab,0,0,0,0,0,0) ){
+      /* Table missing from second database. */
+      printf("DROP TABLE %s;\n", zId);
+    }
+    goto end_diff_one_table;
+  }
+
+  if( sqlite3_table_column_metadata(g.db,"main",zTab,0,0,0,0,0,0) ){
+    /* Table missing from source */
+    dump_table(zTab);
+    goto end_diff_one_table;
+  }
+
+  az = columnNames("main", zTab, &nPk);
+  az2 = columnNames("aux", zTab, &nPk2);
+  if( az && az2 ){
+    for(n=0; az[n]; n++){
+      if( sqlite3_stricmp(az[n],az2[n])!=0 ) break;
+    }
+  }
+  if( az==0
+   || az2==0
+   || nPk!=nPk2
+   || az[n]
+  ){
+    /* Schema mismatch */
+    printf("DROP TABLE %s;\n", zId);
+    dump_table(zTab);
+    goto end_diff_one_table;
+  }
+
+  /* Build the comparison query */
+  for(n2=n; az[n2]; n2++){}
+  nQ = nPk2+1+2*(n2-nPk2);
+  if( n2>nPk2 ){
+    zSep = "SELECT ";
+    for(i=0; i<nPk; i++){
+      strPrintf(&sql, "%sB.%s", zSep, az[i]);
+      zSep = ", ";
+    }
+    strPrintf(&sql, ", 1%s -- changed row\n", nPk==n ? "" : ",");
+    while( az[i] ){
+      strPrintf(&sql, "       A.%s IS NOT B.%s, B.%s%s\n",
+                az[i], az[i], az[i], i==n2-1 ? "" : ",");
+      i++;
+    }
+    strPrintf(&sql, "  FROM main.%s A, aux.%s B\n", zId, zId);
+    zSep = " WHERE";
+    for(i=0; i<nPk; i++){
+      strPrintf(&sql, "%s A.%s=B.%s", zSep, az[i], az[i]);
+      zSep = " AND";
+    }
+    zSep = "\n   AND (";
+    while( az[i] ){
+      strPrintf(&sql, "%sA.%s IS NOT B.%s%s\n",
+                zSep, az[i], az[i], i==n2-1 ? ")" : "");
+      zSep = "        OR ";
+      i++;
+    }
+    strPrintf(&sql, " UNION ALL\n");
+  }
+  zSep = "SELECT ";
+  for(i=0; i<nPk; i++){
+    strPrintf(&sql, "%sA.%s", zSep, az[i]);
+    zSep = ", ";
+  }
+  strPrintf(&sql, ", 2%s -- deleted row\n", nPk==n ? "" : ",");
+  while( az[i] ){
+    strPrintf(&sql, "       NULL, NULL%s\n", i==n2-1 ? "" : ",");
+    i++;
+  }
+  strPrintf(&sql, "  FROM main.%s A\n", zId);
+  strPrintf(&sql, " WHERE NOT EXISTS(SELECT 1 FROM aux.%s B\n", zId);
+  zSep =          "                   WHERE";
+  for(i=0; i<nPk; i++){
+    strPrintf(&sql, "%s A.%s=B.%s", zSep, az[i], az[i]);
+    zSep = " AND";
+  }
+  strPrintf(&sql, ")\n");
+  zSep = " UNION ALL\nSELECT ";
+  for(i=0; i<nPk; i++){
+    strPrintf(&sql, "%sB.%s", zSep, az[i]);
+    zSep = ", ";
+  }
+  strPrintf(&sql, ", 3%s -- inserted row\n", nPk==n ? "" : ",");
+  while( az2[i] ){
+    strPrintf(&sql, "       1, B.%s%s\n", az[i], i==n2-1 ? "" : ",");
+    i++;
+  }
+  strPrintf(&sql, "  FROM aux.%s B\n", zId);
+  strPrintf(&sql, " WHERE NOT EXISTS(SELECT 1 FROM main.%s A\n", zId);
+  zSep =          "                   WHERE";
+  for(i=0; i<nPk; i++){
+    strPrintf(&sql, "%s A.%s=B.%s", zSep, az[i], az[i]);
+    zSep = " AND";
+  }
+  strPrintf(&sql, ")\n ORDER BY");
+  zSep = " ";
+  for(i=1; i<=nPk; i++){
+    strPrintf(&sql, "%s%d", zSep, i);
+    zSep = ", ";
+  }
+  strPrintf(&sql, ";\n");
+
+  if( g.fDebug & DEBUG_DIFF_SQL ){ 
+    printf("SQL for %s:\n%s\n", zId, sql.z);
+    goto end_diff_one_table;
+  }
+
+  /* Drop indexes that are missing in the destination */
+  pStmt = db_prepare(
+    "SELECT name FROM main.sqlite_master"
+    " WHERE type='index' AND tbl_name=%Q"
+    "   AND sql IS NOT NULL"
+    "   AND sql NOT IN (SELECT sql FROM aux.sqlite_master"
+    "                    WHERE type='index' AND tbl_name=%Q"
+    "                      AND sql IS NOT NULL)",
+    zTab, zTab);
+  while( SQLITE_ROW==sqlite3_step(pStmt) ){
+    char *z = safeId((const char*)sqlite3_column_text(pStmt,0));
+    printf("DROP INDEX %s;\n", z);
+    sqlite3_free(z);
+  }
+  sqlite3_finalize(pStmt);
+
+  /* Run the query and output differences */
+  if( !g.bSchemaOnly ){
+    pStmt = db_prepare(sql.z);
+    while( SQLITE_ROW==sqlite3_step(pStmt) ){
+      int iType = sqlite3_column_int(pStmt, nPk);
+      if( iType==1 || iType==2 ){
+        if( iType==1 ){       /* Change the content of a row */
+          printf("UPDATE %s", zId);
+          zSep = " SET";
+          for(i=nPk+1; i<nQ; i+=2){
+            if( sqlite3_column_int(pStmt,i)==0 ) continue;
+            printf("%s %s=", zSep, az2[(i+nPk-1)/2]);
+            zSep = ",";
+            printQuoted(sqlite3_column_value(pStmt,i+1));
+          }
+        }else{                /* Delete a row */
+          printf("DELETE FROM %s", zId);
+        }
+        zSep = " WHERE";
+        for(i=0; i<nPk; i++){
+          printf("%s %s=", zSep, az2[i]);
+          printQuoted(sqlite3_column_value(pStmt,i));
+          zSep = ",";
+        }
+        printf(";\n");
+      }else{                  /* Insert a row */
+        printf("INSERT INTO %s(%s", zId, az2[0]);
+        for(i=1; az2[i]; i++) printf(",%s", az2[i]);
+        printf(") VALUES");
+        zSep = "(";
+        for(i=0; i<nPk2; i++){
+          printf("%s", zSep);
+          zSep = ",";
+          printQuoted(sqlite3_column_value(pStmt,i));
+        }
+        for(i=nPk2+2; i<nQ; i+=2){
+          printf(",");
+          printQuoted(sqlite3_column_value(pStmt,i));
+        }
+        printf(");\n");
+      }
+    }
+    sqlite3_finalize(pStmt);
+  } /* endif !g.bSchemaOnly */
+
+  /* Create indexes that are missing in the source */
+  pStmt = db_prepare(
+    "SELECT sql FROM aux.sqlite_master"
+    " WHERE type='index' AND tbl_name=%Q"
+    "   AND sql IS NOT NULL"
+    "   AND sql NOT IN (SELECT sql FROM main.sqlite_master"
+    "                    WHERE type='index' AND tbl_name=%Q"
+    "                      AND sql IS NOT NULL)",
+    zTab, zTab);
+  while( SQLITE_ROW==sqlite3_step(pStmt) ){
+    printf("%s;\n", sqlite3_column_text(pStmt,0));
+  }
+  sqlite3_finalize(pStmt);
+
+end_diff_one_table:
+  strFree(&sql);
+  sqlite3_free(zId);
+  namelistFree(az);
+  namelistFree(az2);
+  return;
+}
+
+/*
+** Print sketchy documentation for this utility program
+*/
+static void showHelp(void){
+  printf("Usage: %s [options] DB1 DB2\n", g.zArgv0);
+  printf(
+"Output SQL text that would transform DB1 into DB2.\n"
+"Options:\n"
+"  --primarykey          Use schema-defined PRIMARY KEYs\n"
+"  --schema              Show only differences in the schema\n"
+"  --table TAB           Show only differences in table TAB\n"
+  );
+}
+
+int main(int argc, char **argv){
+  const char *zDb1 = 0;
+  const char *zDb2 = 0;
+  int i;
+  int rc;
+  char *zErrMsg = 0;
+  char *zSql;
+  sqlite3_stmt *pStmt;
+  char *zTab = 0;
+
+  g.zArgv0 = argv[0];
+  for(i=1; i<argc; i++){
+    const char *z = argv[i];
+    if( z[0]=='-' ){
+      z++;
+      if( z[0]=='-' ) z++;
+      if( strcmp(z,"debug")==0 ){
+        g.fDebug = strtol(argv[++i], 0, 0);
+      }else
+      if( strcmp(z,"help")==0 ){
+        showHelp();
+        return 0;
+      }else
+      if( strcmp(z,"primarykey")==0 ){
+        g.bSchemaPK = 1;
+      }else
+      if( strcmp(z,"schema")==0 ){
+        g.bSchemaOnly = 1;
+      }else
+      if( strcmp(z,"table")==0 ){
+        zTab = argv[++i];
+      }else
+      {
+        cmdlineError("unknown option: %s", argv[i]);
+      }
+    }else if( zDb1==0 ){
+      zDb1 = argv[i];
+    }else if( zDb2==0 ){
+      zDb2 = argv[i];
+    }else{
+      cmdlineError("unknown argument: %s", argv[i]);
+    }
+  }
+  if( zDb2==0 ){
+    cmdlineError("two database arguments required");
+  }
+  rc = sqlite3_open(zDb1, &g.db);
+  if( rc ){
+    cmdlineError("cannot open database file \"%s\"", zDb1);
+  }
+  rc = sqlite3_exec(g.db, "SELECT * FROM sqlite_master", 0, 0, &zErrMsg);
+  if( rc || zErrMsg ){
+    cmdlineError("\"%s\" does not appear to be a valid SQLite database", zDb1);
+  }
+  zSql = sqlite3_mprintf("ATTACH %Q as aux;", zDb2);
+  rc = sqlite3_exec(g.db, zSql, 0, 0, &zErrMsg);
+  if( rc || zErrMsg ){
+    cmdlineError("cannot attach database \"%s\"", zDb2);
+  }
+  rc = sqlite3_exec(g.db, "SELECT * FROM aux.sqlite_master", 0, 0, &zErrMsg);
+  if( rc || zErrMsg ){
+    cmdlineError("\"%s\" does not appear to be a valid SQLite database", zDb2);
+  }
+
+  if( zTab ){
+    diff_one_table(zTab);
+  }else{
+    /* Handle tables one by one */
+    pStmt = db_prepare(
+      "SELECT name FROM main.sqlite_master\n"
+      " WHERE type='table' AND sql NOT LIKE 'CREATE VIRTUAL%%'\n"
+      " UNION\n"
+      "SELECT name FROM aux.sqlite_master\n"
+      " WHERE type='table' AND sql NOT LIKE 'CREATE VIRTUAL%%'\n"
+      " ORDER BY name"
+    );
+    while( SQLITE_ROW==sqlite3_step(pStmt) ){
+      diff_one_table((const char*)sqlite3_column_text(pStmt, 0));
+    }
+    sqlite3_finalize(pStmt);
+  }
+
+  /* TBD: Handle trigger differences */
+  /* TBD: Handle view differences */
+  sqlite3_close(g.db);
+  return 0;
+}