Merge latest trunk changes with this branch.

FossilOrigin-Name: 251022034219819a1dc356542770ff46e3147a080f072eb20af6106771dadd92

18 files changed, 232 insertions, 113 deletions

diff --git a/src/alter.c b/src/alter.c
index 51d4a4006..f338e8bf4 100644
--- a/src/alter.c
+++ b/src/alter.c
@@ -142,7 +142,7 @@ static void renameParentFunc(
     }
   }
 
-  zResult = sqlite3MPrintf(db, "%s%s", (zOutput?zOutput:""), zInput), 
+  zResult = sqlite3MPrintf(db, "%s%s", (zOutput?zOutput:""), zInput);
   sqlite3_result_text(context, zResult, -1, SQLITE_DYNAMIC);
   sqlite3DbFree(db, zOutput);
 }
diff --git a/src/backup.c b/src/backup.c
index 165144d96..4200940b2 100644
--- a/src/backup.c
+++ b/src/backup.c
@@ -382,7 +382,7 @@ int sqlite3_backup_step(sqlite3_backup *p, int nPage){
     ** before this function exits.
     */
     if( rc==SQLITE_OK && 0==sqlite3BtreeIsInReadTrans(p->pSrc) ){
-      rc = sqlite3BtreeBeginTrans(p->pSrc, 0);
+      rc = sqlite3BtreeBeginTrans(p->pSrc, 0, 0);
       bCloseTrans = 1;
     }
 
@@ -398,10 +398,10 @@ int sqlite3_backup_step(sqlite3_backup *p, int nPage){
 
     /* Lock the destination database, if it is not locked already. */
     if( SQLITE_OK==rc && p->bDestLocked==0
-     && SQLITE_OK==(rc = sqlite3BtreeBeginTrans(p->pDest, 2)) 
+     && SQLITE_OK==(rc = sqlite3BtreeBeginTrans(p->pDest, 2,
+                                                (int*)&p->iDestSchema)) 
     ){
       p->bDestLocked = 1;
-      sqlite3BtreeGetMeta(p->pDest, BTREE_SCHEMA_VERSION, &p->iDestSchema);
     }
 
     /* Do not allow backup if the destination database is in WAL mode
diff --git a/src/btree.c b/src/btree.c
index 0971575dc..51c6d07e5 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -3300,7 +3300,7 @@ int sqlite3BtreeNewDb(Btree *p){
 ** when A already has a read lock, we encourage A to give up and let B
 ** proceed.
 */
-int sqlite3BtreeBeginTrans(Btree *p, int wrflag){
+int sqlite3BtreeBeginTrans(Btree *p, int wrflag, int *pSchemaVersion){
   BtShared *pBt = p->pBt;
   int rc = SQLITE_OK;
 
@@ -3428,12 +3428,17 @@ int sqlite3BtreeBeginTrans(Btree *p, int wrflag){
 
 
 trans_begun:
-  if( rc==SQLITE_OK && wrflag ){
-    /* This call makes sure that the pager has the correct number of
-    ** open savepoints. If the second parameter is greater than 0 and
-    ** the sub-journal is not already open, then it will be opened here.
-    */
-    rc = sqlite3PagerOpenSavepoint(pBt->pPager, p->db->nSavepoint);
+  if( rc==SQLITE_OK ){
+    if( pSchemaVersion ){
+      *pSchemaVersion = get4byte(&pBt->pPage1->aData[40]);
+    }
+    if( wrflag ){
+      /* This call makes sure that the pager has the correct number of
+      ** open savepoints. If the second parameter is greater than 0 and
+      ** the sub-journal is not already open, then it will be opened here.
+      */
+      rc = sqlite3PagerOpenSavepoint(pBt->pPager, p->db->nSavepoint);
+    }
   }
 
   btreeIntegrity(p);
@@ -10091,11 +10096,11 @@ int sqlite3BtreeSetVersion(Btree *pBtree, int iVersion){
   pBt->btsFlags &= ~BTS_NO_WAL;
   if( iVersion==1 ) pBt->btsFlags |= BTS_NO_WAL;
 
-  rc = sqlite3BtreeBeginTrans(pBtree, 0);
+  rc = sqlite3BtreeBeginTrans(pBtree, 0, 0);
   if( rc==SQLITE_OK ){
     u8 *aData = pBt->pPage1->aData;
     if( aData[18]!=(u8)iVersion || aData[19]!=(u8)iVersion ){
-      rc = sqlite3BtreeBeginTrans(pBtree, 2);
+      rc = sqlite3BtreeBeginTrans(pBtree, 2, 0);
       if( rc==SQLITE_OK ){
         rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
         if( rc==SQLITE_OK ){
diff --git a/src/btree.h b/src/btree.h
index 20fdbdae2..0b9784979 100644
--- a/src/btree.h
+++ b/src/btree.h
@@ -78,7 +78,7 @@ int sqlite3BtreeGetOptimalReserve(Btree*);
 int sqlite3BtreeGetReserveNoMutex(Btree *p);
 int sqlite3BtreeSetAutoVacuum(Btree *, int);
 int sqlite3BtreeGetAutoVacuum(Btree *);
-int sqlite3BtreeBeginTrans(Btree*,int);
+int sqlite3BtreeBeginTrans(Btree*,int,int*);
 int sqlite3BtreeCommitPhaseOne(Btree*, const char *zMaster);
 int sqlite3BtreeCommitPhaseTwo(Btree*, int);
 int sqlite3BtreeCommit(Btree*);
diff --git a/src/dbpage.c b/src/dbpage.c
index c38de3b39..5b19abd35 100644
--- a/src/dbpage.c
+++ b/src/dbpage.c
@@ -369,7 +369,7 @@ static int dbpageBegin(sqlite3_vtab *pVtab){
   int i;
   for(i=0; i<db->nDb; i++){
     Btree *pBt = db->aDb[i].pBt;
-    if( pBt ) sqlite3BtreeBeginTrans(pBt, 1);
+    if( pBt ) sqlite3BtreeBeginTrans(pBt, 1, 0);
   }
   return SQLITE_OK;
 }
diff --git a/src/main.c b/src/main.c
index 8e89cc553..a2b994f9b 100644
--- a/src/main.c
+++ b/src/main.c
@@ -4115,7 +4115,7 @@ int sqlite3_snapshot_get(
     if( iDb==0 || iDb>1 ){
       Btree *pBt = db->aDb[iDb].pBt;
       if( 0==sqlite3BtreeIsInTrans(pBt) ){
-        rc = sqlite3BtreeBeginTrans(pBt, 0);
+        rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
         if( rc==SQLITE_OK ){
           rc = sqlite3PagerSnapshotGet(sqlite3BtreePager(pBt), ppSnapshot);
         }
@@ -4153,7 +4153,7 @@ int sqlite3_snapshot_open(
       if( 0==sqlite3BtreeIsInReadTrans(pBt) ){
         rc = sqlite3PagerSnapshotOpen(sqlite3BtreePager(pBt), pSnapshot);
         if( rc==SQLITE_OK ){
-          rc = sqlite3BtreeBeginTrans(pBt, 0);
+          rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
           sqlite3PagerSnapshotOpen(sqlite3BtreePager(pBt), 0);
         }
       }
@@ -4185,7 +4185,7 @@ int sqlite3_snapshot_recover(sqlite3 *db, const char *zDb){
   if( iDb==0 || iDb>1 ){
     Btree *pBt = db->aDb[iDb].pBt;
     if( 0==sqlite3BtreeIsInReadTrans(pBt) ){
-      rc = sqlite3BtreeBeginTrans(pBt, 0);
+      rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
       if( rc==SQLITE_OK ){
         rc = sqlite3PagerSnapshotRecover(sqlite3BtreePager(pBt));
         sqlite3BtreeCommit(pBt);
diff --git a/src/pragma.c b/src/pragma.c
index 4699c96a1..02510188f 100644
--- a/src/pragma.c
+++ b/src/pragma.c
@@ -1564,6 +1564,11 @@ void sqlite3Pragma(
         assert( sqlite3NoTempsInRange(pParse,1,7+j) );
         sqlite3VdbeAddOp2(v, OP_Rewind, iDataCur, 0); VdbeCoverage(v);
         loopTop = sqlite3VdbeAddOp2(v, OP_AddImm, 7, 1);
+        if( !isQuick ){
+          /* Sanity check on record header decoding */
+          sqlite3VdbeAddOp3(v, OP_Column, iDataCur, pTab->nCol-1, 3);
+          sqlite3VdbeChangeP5(v, OPFLAG_TYPEOFARG);
+        }
         /* Verify that all NOT NULL columns really are NOT NULL */
         for(j=0; j<pTab->nCol; j++){
           char *zErr;
@@ -1606,9 +1611,6 @@ void sqlite3Pragma(
           sqlite3ExprListDelete(db, pCheck);
         }
         if( !isQuick ){ /* Omit the remaining tests for quick_check */
-          /* Sanity check on record header decoding */
-          sqlite3VdbeAddOp3(v, OP_Column, iDataCur, pTab->nCol-1, 3);
-          sqlite3VdbeChangeP5(v, OPFLAG_TYPEOFARG);
           /* Validate index entries for the current row */
           for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
             int jmp2, jmp3, jmp4, jmp5;
diff --git a/src/prepare.c b/src/prepare.c
index c745f45a5..92902ca70 100644
--- a/src/prepare.c
+++ b/src/prepare.c
@@ -188,7 +188,7 @@ static int sqlite3InitOne(sqlite3 *db, int iDb, char **pzErrMsg){
   ** will be closed before this function returns.  */
   sqlite3BtreeEnter(pDb->pBt);
   if( !sqlite3BtreeIsInReadTrans(pDb->pBt) ){
-    rc = sqlite3BtreeBeginTrans(pDb->pBt, 0);
+    rc = sqlite3BtreeBeginTrans(pDb->pBt, 0, 0);
     if( rc!=SQLITE_OK ){
       sqlite3SetString(pzErrMsg, db, sqlite3ErrStr(rc));
       goto initone_error_out;
@@ -433,7 +433,7 @@ static void schemaIsValid(Parse *pParse){
     ** on the b-tree database, open one now. If a transaction is opened, it 
     ** will be closed immediately after reading the meta-value. */
     if( !sqlite3BtreeIsInReadTrans(pBt) ){
-      rc = sqlite3BtreeBeginTrans(pBt, 0);
+      rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
       if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
         sqlite3OomFault(db);
       }
diff --git a/src/select.c b/src/select.c
index cf1034bb6..5e99c949a 100644
--- a/src/select.c
+++ b/src/select.c
@@ -5104,11 +5104,17 @@ static void finalizeAggFunctions(Parse *pParse, AggInfo *pAggInfo){
   }
 }
 
+
 /*
 ** Update the accumulator memory cells for an aggregate based on
 ** the current cursor position.
+**
+** If regAcc is non-zero and there are no min() or max() aggregates
+** in pAggInfo, then only populate the pAggInfo->nAccumulator accumulator
+** registers i register regAcc contains 0. The caller will take care
+** of setting and clearing regAcc.
 */
-static void updateAccumulator(Parse *pParse, AggInfo *pAggInfo){
+static void updateAccumulator(Parse *pParse, int regAcc, AggInfo *pAggInfo){
   Vdbe *v = pParse->pVdbe;
   int i;
   int regHit = 0;
@@ -5172,6 +5178,9 @@ static void updateAccumulator(Parse *pParse, AggInfo *pAggInfo){
   ** Another solution would be to change the OP_SCopy used to copy cached
   ** values to an OP_Copy.
   */
+  if( regHit==0 && pAggInfo->nAccumulator ){
+    regHit = regAcc;
+  }
   if( regHit ){
     addrHitTest = sqlite3VdbeAddOp1(v, OP_If, regHit); VdbeCoverage(v);
   }
@@ -6067,8 +6076,6 @@ int sqlite3Select(
       pParse->nMem += pGroupBy->nExpr;
       sqlite3VdbeAddOp2(v, OP_Integer, 0, iAbortFlag);
       VdbeComment((v, "clear abort flag"));
-      sqlite3VdbeAddOp2(v, OP_Integer, 0, iUseFlag);
-      VdbeComment((v, "indicate accumulator empty"));
       sqlite3VdbeAddOp3(v, OP_Null, 0, iAMem, iAMem+pGroupBy->nExpr-1);
 
       /* Begin a loop that will extract all source rows in GROUP BY order.
@@ -6201,7 +6208,7 @@ int sqlite3Select(
       ** the current row
       */
       sqlite3VdbeJumpHere(v, addr1);
-      updateAccumulator(pParse, &sAggInfo);
+      updateAccumulator(pParse, iUseFlag, &sAggInfo);
       sqlite3VdbeAddOp2(v, OP_Integer, 1, iUseFlag);
       VdbeComment((v, "indicate data in accumulator"));
 
@@ -6253,6 +6260,8 @@ int sqlite3Select(
       */
       sqlite3VdbeResolveLabel(v, addrReset);
       resetAccumulator(pParse, &sAggInfo);
+      sqlite3VdbeAddOp2(v, OP_Integer, 0, iUseFlag);
+      VdbeComment((v, "indicate accumulator empty"));
       sqlite3VdbeAddOp1(v, OP_Return, regReset);
      
     } /* endif pGroupBy.  Begin aggregate queries without GROUP BY: */
@@ -6318,6 +6327,23 @@ int sqlite3Select(
       }else
 #endif /* SQLITE_OMIT_BTREECOUNT */
       {
+        int regAcc = 0;           /* "populate accumulators" flag */
+
+        /* If there are accumulator registers but no min() or max() functions,
+        ** allocate register regAcc. Register regAcc will contain 0 the first
+        ** time the inner loop runs, and 1 thereafter. The code generated
+        ** by updateAccumulator() only updates the accumulator registers if
+        ** regAcc contains 0.  */
+        if( sAggInfo.nAccumulator ){
+          for(i=0; i<sAggInfo.nFunc; i++){
+            if( sAggInfo.aFunc[i].pFunc->funcFlags&SQLITE_FUNC_NEEDCOLL ) break;
+          }
+          if( i==sAggInfo.nFunc ){
+            regAcc = ++pParse->nMem;
+            sqlite3VdbeAddOp2(v, OP_Integer, 0, regAcc);
+          }
+        }
+
         /* This case runs if the aggregate has no GROUP BY clause.  The
         ** processing is much simpler since there is only a single row
         ** of output.
@@ -6339,7 +6365,8 @@ int sqlite3Select(
         if( pWInfo==0 ){
           goto select_end;
         }
-        updateAccumulator(pParse, &sAggInfo);
+        updateAccumulator(pParse, regAcc, &sAggInfo);
+        if( regAcc ) sqlite3VdbeAddOp2(v, OP_Integer, 1, regAcc);
         if( sqlite3WhereIsOrdered(pWInfo)>0 ){
           sqlite3VdbeGoto(v, sqlite3WhereBreakLabel(pWInfo));
           VdbeComment((v, "%s() by index",
diff --git a/src/shell.c.in b/src/shell.c.in
index b9d7cecbc..392580733 100644
--- a/src/shell.c.in
+++ b/src/shell.c.in
@@ -2567,8 +2567,7 @@ static void explain_data_prepare(ShellState *p, sqlite3_stmt *pSql){
   int nAlloc = 0;                 /* Allocated size of p->aiIndent[], abYield */
   int iOp;                        /* Index of operation in p->aiIndent[] */
 
-  const char *azNext[] = { "Next", "Prev", "VPrev", "VNext", "SorterNext",
-                           "NextIfOpen", "PrevIfOpen", 0 };
+  const char *azNext[] = { "Next", "Prev", "VPrev", "VNext", "SorterNext", 0 };
   const char *azYield[] = { "Yield", "SeekLT", "SeekGT", "RowSetRead",
                             "Rewind", 0 };
   const char *azGoto[] = { "Goto", 0 };
@@ -2972,6 +2971,7 @@ static int shell_exec(
           /* Reprepare pStmt before reactiving trace modes */
           sqlite3_finalize(pStmt);
           sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
+          if( pArg ) pArg->pStmt = pStmt;
         }
         restore_debug_trace_modes();
       }
@@ -5284,7 +5284,8 @@ static int arExtractCommand(ArCommand *pAr){
     "SELECT "
     " ($dir || name),"
     " writefile(($dir || name), %s, mode, mtime) "
-    "FROM %s WHERE (%s) AND (data IS NULL OR $dirOnly = 0)";
+    "FROM %s WHERE (%s) AND (data IS NULL OR $dirOnly = 0)"
+    " AND name NOT GLOB '*..[/\\]*'";
 
   const char *azExtraArg[] = { 
     "sqlar_uncompress(data, sz)",
diff --git a/src/test3.c b/src/test3.c
index 0de19469a..d1626b6ef 100644
--- a/src/test3.c
+++ b/src/test3.c
@@ -133,7 +133,7 @@ static int SQLITE_TCLAPI btree_begin_transaction(
   }
   pBt = sqlite3TestTextToPtr(argv[1]);
   sqlite3BtreeEnter(pBt);
-  rc = sqlite3BtreeBeginTrans(pBt, 1);
+  rc = sqlite3BtreeBeginTrans(pBt, 1, 0);
   sqlite3BtreeLeave(pBt);
   if( rc!=SQLITE_OK ){
     Tcl_AppendResult(interp, sqlite3ErrName(rc), 0);
diff --git a/src/vacuum.c b/src/vacuum.c
index fe295147c..04ad5e7a3 100644
--- a/src/vacuum.c
+++ b/src/vacuum.c
@@ -224,7 +224,7 @@ int sqlite3RunVacuum(char **pzErrMsg, sqlite3 *db, int iDb){
   */
   rc = execSql(db, pzErrMsg, "BEGIN");
   if( rc!=SQLITE_OK ) goto end_of_vacuum;
-  rc = sqlite3BtreeBeginTrans(pMain, 2);
+  rc = sqlite3BtreeBeginTrans(pMain, 2, 0);
   if( rc!=SQLITE_OK ) goto end_of_vacuum;
 
   /* Do not attempt to change the page size for a WAL database */
diff --git a/src/vdbe.c b/src/vdbe.c
index ef5c0a163..42581caee 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -3202,8 +3202,7 @@ case OP_AutoCommit: {
 */
 case OP_Transaction: {
   Btree *pBt;
-  int iMeta;
-  int iGen;
+  int iMeta = 0;
 
   assert( p->bIsReader );
   assert( p->readOnly==0 || pOp->p2==0 );
@@ -3216,7 +3215,7 @@ case OP_Transaction: {
   pBt = db->aDb[pOp->p1].pBt;
 
   if( pBt ){
-    rc = sqlite3BtreeBeginTrans(pBt, pOp->p2);
+    rc = sqlite3BtreeBeginTrans(pBt, pOp->p2, &iMeta);
     testcase( rc==SQLITE_BUSY_SNAPSHOT );
     testcase( rc==SQLITE_BUSY_RECOVERY );
     if( rc!=SQLITE_OK ){
@@ -3249,19 +3248,17 @@ case OP_Transaction: {
       p->nStmtDefCons = db->nDeferredCons;
       p->nStmtDefImmCons = db->nDeferredImmCons;
     }
-
-    /* Gather the schema version number for checking:
+  }
+  assert( pOp->p5==0 || pOp->p4type==P4_INT32 );
+  if( pOp->p5
+   && (iMeta!=pOp->p3
+      || db->aDb[pOp->p1].pSchema->iGeneration!=pOp->p4.i)
+  ){
+    /*
     ** IMPLEMENTATION-OF: R-03189-51135 As each SQL statement runs, the schema
     ** version is checked to ensure that the schema has not changed since the
     ** SQL statement was prepared.
     */
-    sqlite3BtreeGetMeta(pBt, BTREE_SCHEMA_VERSION, (u32 *)&iMeta);
-    iGen = db->aDb[pOp->p1].pSchema->iGeneration;
-  }else{
-    iGen = iMeta = 0;
-  }
-  assert( pOp->p5==0 || pOp->p4type==P4_INT32 );
-  if( pOp->p5 && (iMeta!=pOp->p3 || iGen!=pOp->p4.i) ){
     sqlite3DbFree(db, p->zErrMsg);
     p->zErrMsg = sqlite3DbStrDup(db, "database schema has changed");
     /* If the schema-cookie from the database file matches the cookie 
@@ -3370,59 +3367,78 @@ case OP_SetCookie: {
 ** values need not be contiguous but all P1 values should be small integers.
 ** It is an error for P1 to be negative.
 **
-** If P5!=0 then use the content of register P2 as the root page, not
-** the value of P2 itself.
-**
-** There will be a read lock on the database whenever there is an
-** open cursor.  If the database was unlocked prior to this instruction
-** then a read lock is acquired as part of this instruction.  A read
-** lock allows other processes to read the database but prohibits
-** any other process from modifying the database.  The read lock is
-** released when all cursors are closed.  If this instruction attempts
-** to get a read lock but fails, the script terminates with an
-** SQLITE_BUSY error code.
+** Allowed P5 bits:
+** <ul>
+** <li>  <b>0x02 OPFLAG_SEEKEQ</b>: This cursor will only be used for
+**       equality lookups (implemented as a pair of opcodes OP_SeekGE/OP_IdxGT
+**       of OP_SeekLE/OP_IdxGT)
+** </ul>
 **
 ** The P4 value may be either an integer (P4_INT32) or a pointer to
 ** a KeyInfo structure (P4_KEYINFO). If it is a pointer to a KeyInfo 
-** structure, then said structure defines the content and collating 
-** sequence of the index being opened. Otherwise, if P4 is an integer 
-** value, it is set to the number of columns in the table.
+** object, then table being opened must be an [index b-tree] where the
+** KeyInfo object defines the content and collating 
+** sequence of that index b-tree. Otherwise, if P4 is an integer 
+** value, then the table being opened must be a [table b-tree] with a
+** number of columns no less than the value of P4.
 **
 ** See also: OpenWrite, ReopenIdx
 */
 /* Opcode: ReopenIdx P1 P2 P3 P4 P5
 ** Synopsis: root=P2 iDb=P3
 **
-** The ReopenIdx opcode works exactly like ReadOpen except that it first
-** checks to see if the cursor on P1 is already open with a root page
-** number of P2 and if it is this opcode becomes a no-op.  In other words,
+** The ReopenIdx opcode works like OP_OpenRead except that it first
+** checks to see if the cursor on P1 is already open on the same
+** b-tree and if it is this opcode becomes a no-op.  In other words,
 ** if the cursor is already open, do not reopen it.
 **
-** The ReopenIdx opcode may only be used with P5==0 and with P4 being
-** a P4_KEYINFO object.  Furthermore, the P3 value must be the same as
-** every other ReopenIdx or OpenRead for the same cursor number.
+** The ReopenIdx opcode may only be used with P5==0 or P5==OPFLAG_SEEKEQ
+** and with P4 being a P4_KEYINFO object.  Furthermore, the P3 value must
+** be the same as every other ReopenIdx or OpenRead for the same cursor
+** number.
 **
-** See the OpenRead opcode documentation for additional information.
+** Allowed P5 bits:
+** <ul>
+** <li>  <b>0x02 OPFLAG_SEEKEQ</b>: This cursor will only be used for
+**       equality lookups (implemented as a pair of opcodes OP_SeekGE/OP_IdxGT
+**       of OP_SeekLE/OP_IdxGT)
+** </ul>
+**
+** See also: OP_OpenRead, OP_OpenWrite
 */
 /* Opcode: OpenWrite P1 P2 P3 P4 P5
 ** Synopsis: root=P2 iDb=P3
 **
 ** Open a read/write cursor named P1 on the table or index whose root
-** page is P2.  Or if P5!=0 use the content of register P2 to find the
-** root page.
+** page is P2 (or whose root page is held in register P2 if the
+** OPFLAG_P2ISREG bit is set in P5 - see below).
 **
 ** The P4 value may be either an integer (P4_INT32) or a pointer to
 ** a KeyInfo structure (P4_KEYINFO). If it is a pointer to a KeyInfo 
-** structure, then said structure defines the content and collating 
-** sequence of the index being opened. Otherwise, if P4 is an integer 
-** value, it is set to the number of columns in the table, or to the
-** largest index of any column of the table that is actually used.
+** object, then table being opened must be an [index b-tree] where the
+** KeyInfo object defines the content and collating 
+** sequence of that index b-tree. Otherwise, if P4 is an integer 
+** value, then the table being opened must be a [table b-tree] with a
+** number of columns no less than the value of P4.
+**
+** Allowed P5 bits:
+** <ul>
+** <li>  <b>0x02 OPFLAG_SEEKEQ</b>: This cursor will only be used for
+**       equality lookups (implemented as a pair of opcodes OP_SeekGE/OP_IdxGT
+**       of OP_SeekLE/OP_IdxGT)
+** <li>  <b>0x08 OPFLAG_FORDELETE</b>: This cursor is used only to seek
+**       and subsequently delete entries in an index btree.  This is a
+**       hint to the storage engine that the storage engine is allowed to
+**       ignore.  The hint is not used by the official SQLite b*tree storage
+**       engine, but is used by COMDB2.
+** <li>  <b>0x10 OPFLAG_P2ISREG</b>: Use the content of register P2
+**       as the root page, not the value of P2 itself.
+** </ul>
 **
-** This instruction works just like OpenRead except that it opens the cursor
-** in read/write mode.  For a given table, there can be one or more read-only
-** cursors or a single read/write cursor but not both.
+** This instruction works like OpenRead except that it opens the cursor
+** in read/write mode.
 **
-** See also OpenRead.
+** See also: OP_OpenRead, OP_ReopenIdx
 */
 case OP_ReopenIdx: {
   int nField;
@@ -3478,6 +3494,7 @@ case OP_OpenWrite:
   if( pOp->p5 & OPFLAG_P2ISREG ){
     assert( p2>0 );
     assert( p2<=(p->nMem+1 - p->nCursor) );
+    assert( pOp->opcode==OP_OpenWrite );
     pIn2 = &aMem[p2];
     assert( memIsValid(pIn2) );
     assert( (pIn2->flags & MEM_Int)!=0 );
@@ -3606,7 +3623,7 @@ case OP_OpenEphemeral: {
   rc = sqlite3BtreeOpen(db->pVfs, 0, db, &pCx->pBtx, 
                         BTREE_OMIT_JOURNAL | BTREE_SINGLE | pOp->p5, vfsFlags);
   if( rc==SQLITE_OK ){
-    rc = sqlite3BtreeBeginTrans(pCx->pBtx, 1);
+    rc = sqlite3BtreeBeginTrans(pCx->pBtx, 1, 0);
   }
   if( rc==SQLITE_OK ){
     /* If a transient index is required, create it by calling
@@ -4014,6 +4031,25 @@ seek_not_found:
   break;
 }
 
+/* Opcode: SeekHit P1 P2 * * *
+** Synopsis: seekHit=P2
+**
+** Set the seekHit flag on cursor P1 to the value in P2.
+** The seekHit flag is used by the IfNoHope opcode.
+**
+** P1 must be a valid b-tree cursor.  P2 must be a boolean value,
+** either 0 or 1.
+*/
+case OP_SeekHit: {
+  VdbeCursor *pC;
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+  assert( pOp->p2==0 || pOp->p2==1 );
+  pC->seekHit = pOp->p2 & 1;
+  break;
+}
+
 /* Opcode: Found P1 P2 P3 P4 *
 ** Synopsis: key=r[P3@P4]
 **
@@ -4048,7 +4084,34 @@ seek_not_found:
 ** advanced in either direction.  In other words, the Next and Prev
 ** opcodes do not work after this operation.
 **
-** See also: Found, NotExists, NoConflict
+** See also: Found, NotExists, NoConflict, IfNoHope
+*/
+/* Opcode: IfNoHope P1 P2 P3 P4 *
+** Synopsis: key=r[P3@P4]
+**
+** Register P3 is the first of P4 registers that form an unpacked
+** record.
+**
+** Cursor P1 is on an index btree.  If the seekHit flag is set on P1, then
+** this opcode is a no-op.  But if the seekHit flag of P1 is clear, then
+** check to see if there is any entry in P1 that matches the
+** prefix identified by P3 and P4.  If no entry matches the prefix,
+** jump to P2.  Otherwise fall through.
+**
+** This opcode behaves like OP_NotFound if the seekHit
+** flag is clear and it behaves like OP_Noop if the seekHit flag is set.
+**
+** This opcode is used in IN clause processing for a multi-column key.
+** If an IN clause is attached to an element of the key other than the
+** left-most element, and if there are no matches on the most recent
+** seek over the whole key, then it might be that one of the key element
+** to the left is prohibiting a match, and hence there is "no hope" of
+** any match regardless of how many IN clause elements are checked.
+** In such a case, we abandon the IN clause search early, using this
+** opcode.  The opcode name comes from the fact that the
+** jump is taken if there is "no hope" of achieving a match.
+**
+** See also: NotFound, SeekHit
 */
 /* Opcode: NoConflict P1 P2 P3 P4 *
 ** Synopsis: key=r[P3@P4]
@@ -4073,6 +4136,14 @@ seek_not_found:
 **
 ** See also: NotFound, Found, NotExists
 */
+case OP_IfNoHope: {     /* jump, in3 */
+  VdbeCursor *pC;
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  pC = p->apCsr[pOp->p1];
+  assert( pC!=0 );
+  if( pC->seekHit ) break;
+  /* Fall through into OP_NotFound */
+}
 case OP_NoConflict:     /* jump, in3 */
 case OP_NotFound:       /* jump, in3 */
 case OP_Found: {        /* jump, in3 */
@@ -4221,7 +4292,7 @@ case OP_NotExists:          /* jump, in3 */
   pC = p->apCsr[pOp->p1];
   assert( pC!=0 );
 #ifdef SQLITE_DEBUG
-  pC->seekOp = 0;
+  pC->seekOp = OP_SeekRowid;
 #endif
   assert( pC->isTable );
   assert( pC->eCurType==CURTYPE_BTREE );
@@ -4875,6 +4946,9 @@ case OP_NullRow: {
     assert( pC->uc.pCursor!=0 );
     sqlite3BtreeClearCursor(pC->uc.pCursor);
   }
+#ifdef SQLITE_DEBUG
+  if( pC->seekOp==0 ) pC->seekOp = OP_NullRow;
+#endif
   break;
 }
 
@@ -5062,12 +5136,7 @@ case OP_Rewind: {        /* jump */
 ** If P5 is positive and the jump is taken, then event counter
 ** number P5-1 in the prepared statement is incremented.
 **
-** See also: Prev, NextIfOpen
-*/
-/* Opcode: NextIfOpen P1 P2 P3 P4 P5
-**
-** This opcode works just like Next except that if cursor P1 is not
-** open it behaves a no-op.
+** See also: Prev
 */
 /* Opcode: Prev P1 P2 P3 P4 P5
 **
@@ -5095,11 +5164,6 @@ case OP_Rewind: {        /* jump */
 ** If P5 is positive and the jump is taken, then event counter
 ** number P5-1 in the prepared statement is incremented.
 */
-/* Opcode: PrevIfOpen P1 P2 P3 P4 P5
-**
-** This opcode works just like Prev except that if cursor P1 is not
-** open it behaves a no-op.
-*/
 /* Opcode: SorterNext P1 P2 * * P5
 **
 ** This opcode works just like OP_Next except that P1 must be a
@@ -5114,10 +5178,6 @@ case OP_SorterNext: {  /* jump */
   assert( isSorter(pC) );
   rc = sqlite3VdbeSorterNext(db, pC);
   goto next_tail;
-case OP_PrevIfOpen:    /* jump */
-case OP_NextIfOpen:    /* jump */
-  if( p->apCsr[pOp->p1]==0 ) break;
-  /* Fall through */
 case OP_Prev:          /* jump */
 case OP_Next:          /* jump */
   assert( pOp->p1>=0 && pOp->p1<p->nCursor );
@@ -5128,17 +5188,17 @@ case OP_Next:          /* jump */
   assert( pC->eCurType==CURTYPE_BTREE );
   assert( pOp->opcode!=OP_Next || pOp->p4.xAdvance==sqlite3BtreeNext );
   assert( pOp->opcode!=OP_Prev || pOp->p4.xAdvance==sqlite3BtreePrevious );
-  assert( pOp->opcode!=OP_NextIfOpen || pOp->p4.xAdvance==sqlite3BtreeNext );
-  assert( pOp->opcode!=OP_PrevIfOpen || pOp->p4.xAdvance==sqlite3BtreePrevious);
 
-  /* The Next opcode is only used after SeekGT, SeekGE, and Rewind.
+  /* The Next opcode is only used after SeekGT, SeekGE, Rewind, and Found.
   ** The Prev opcode is only used after SeekLT, SeekLE, and Last. */
-  assert( pOp->opcode!=OP_Next || pOp->opcode!=OP_NextIfOpen
+  assert( pOp->opcode!=OP_Next
        || pC->seekOp==OP_SeekGT || pC->seekOp==OP_SeekGE
-       || pC->seekOp==OP_Rewind || pC->seekOp==OP_Found);
-  assert( pOp->opcode!=OP_Prev || pOp->opcode!=OP_PrevIfOpen
+       || pC->seekOp==OP_Rewind || pC->seekOp==OP_Found 
+       || pC->seekOp==OP_NullRow);
+  assert( pOp->opcode!=OP_Prev
        || pC->seekOp==OP_SeekLT || pC->seekOp==OP_SeekLE
-       || pC->seekOp==OP_Last );
+       || pC->seekOp==OP_Last 
+       || pC->seekOp==OP_NullRow);
 
   rc = pOp->p4.xAdvance(pC->uc.pCursor, pOp->p3);
 next_tail:
diff --git a/src/vdbeInt.h b/src/vdbeInt.h
index aaa935682..7acac081b 100644
--- a/src/vdbeInt.h
+++ b/src/vdbeInt.h
@@ -85,6 +85,7 @@ struct VdbeCursor {
   Bool isEphemeral:1;     /* True for an ephemeral table */
   Bool useRandomRowid:1;  /* Generate new record numbers semi-randomly */
   Bool isOrdered:1;       /* True if the table is not BTREE_UNORDERED */
+  Bool seekHit:1;         /* See the OP_SeekHit and OP_IfNoHope opcodes */
   Btree *pBtx;            /* Separate file holding temporary table */
   i64 seqCount;           /* Sequence counter */
   int *aAltMap;           /* Mapping from table to index column numbers */
diff --git a/src/vdbeaux.c b/src/vdbeaux.c
index 38ef85f0e..7f0448ec1 100644
--- a/src/vdbeaux.c
+++ b/src/vdbeaux.c
@@ -689,7 +689,6 @@ static void resolveP2Values(Vdbe *p, int *pMaxFuncArgs){
           break;
         }
         case OP_Next:
-        case OP_NextIfOpen:
         case OP_SorterNext: {
           pOp->p4.xAdvance = sqlite3BtreeNext;
           pOp->p4type = P4_ADVANCE;
@@ -699,8 +698,7 @@ static void resolveP2Values(Vdbe *p, int *pMaxFuncArgs){
           assert( pOp->p2>=0 );
           break;
         }
-        case OP_Prev:
-        case OP_PrevIfOpen: {
+        case OP_Prev: {
           pOp->p4.xAdvance = sqlite3BtreePrevious;
           pOp->p4type = P4_ADVANCE;
           /* The code generator never codes any of these opcodes as a jump
@@ -4129,7 +4127,7 @@ int sqlite3VdbeRecordCompareWithSkip(
   u32 idx1;                       /* Offset of first type in header */
   int rc = 0;                     /* Return value */
   Mem *pRhs = pPKey2->aMem;       /* Next field of pPKey2 to compare */
-  KeyInfo *pKeyInfo = pPKey2->pKeyInfo;
+  KeyInfo *pKeyInfo;
   const unsigned char *aKey1 = (const unsigned char *)pKey1;
   Mem mem1;
 
@@ -4224,7 +4222,7 @@ int sqlite3VdbeRecordCompareWithSkip(
         if( (d1+mem1.n) > (unsigned)nKey1 ){
           pPKey2->errCode = (u8)SQLITE_CORRUPT_BKPT;
           return 0;                /* Corruption */
-        }else if( pKeyInfo->aColl[i] ){
+        }else if( (pKeyInfo = pPKey2->pKeyInfo)->aColl[i] ){
           mem1.enc = pKeyInfo->enc;
           mem1.db = pKeyInfo->db;
           mem1.flags = MEM_Str;
@@ -4275,7 +4273,7 @@ int sqlite3VdbeRecordCompareWithSkip(
     }
 
     if( rc!=0 ){
-      if( pKeyInfo->aSortOrder[i] ){
+      if( pPKey2->pKeyInfo->aSortOrder[i] ){
         rc = -rc;
       }
       assert( vdbeRecordCompareDebug(nKey1, pKey1, pPKey2, rc) );
@@ -4284,10 +4282,11 @@ int sqlite3VdbeRecordCompareWithSkip(
     }
 
     i++;
+    if( i==pPKey2->nField ) break;
     pRhs++;
     d1 += sqlite3VdbeSerialTypeLen(serial_type);
     idx1 += sqlite3VarintLen(serial_type);
-  }while( idx1<(unsigned)szHdr1 && i<pPKey2->nField && d1<=(unsigned)nKey1 );
+  }while( idx1<(unsigned)szHdr1 && d1<=(unsigned)nKey1 );
 
   /* No memory allocation is ever used on mem1.  Prove this using
   ** the following assert().  If the assert() fails, it indicates a
@@ -4299,7 +4298,7 @@ int sqlite3VdbeRecordCompareWithSkip(
   ** value.  */
   assert( CORRUPT_DB 
        || vdbeRecordCompareDebug(nKey1, pKey1, pPKey2, pPKey2->default_rc) 
-       || pKeyInfo->db->mallocFailed
+       || pPKey2->pKeyInfo->db->mallocFailed
   );
   pPKey2->eqSeen = 1;
   return pPKey2->default_rc;
@@ -4625,7 +4624,7 @@ int sqlite3VdbeIdxKeyCompare(
   if( rc ){
     return rc;
   }
-  *res = sqlite3VdbeRecordCompare(m.n, m.z, pUnpacked);
+  *res = sqlite3VdbeRecordCompareWithSkip(m.n, m.z, pUnpacked, 0);
   sqlite3VdbeMemRelease(&m);
   return SQLITE_OK;
 }
diff --git a/src/where.c b/src/where.c
index b83915e26..10cb13814 100644
--- a/src/where.c
+++ b/src/where.c
@@ -5083,10 +5083,17 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
       for(j=pLevel->u.in.nIn, pIn=&pLevel->u.in.aInLoop[j-1]; j>0; j--, pIn--){
         sqlite3VdbeJumpHere(v, pIn->addrInTop+1);
         if( pIn->eEndLoopOp!=OP_Noop ){
+          if( pIn->nPrefix ){
+            assert( pLoop->wsFlags & WHERE_IN_EARLYOUT );
+            sqlite3VdbeAddOp4Int(v, OP_IfNoHope, pLevel->iIdxCur,
+                              sqlite3VdbeCurrentAddr(v)+2,
+                              pIn->iBase, pIn->nPrefix);
+            VdbeCoverage(v);
+          }
           sqlite3VdbeAddOp2(v, pIn->eEndLoopOp, pIn->iCur, pIn->addrInTop);
           VdbeCoverage(v);
-          VdbeCoverageIf(v, pIn->eEndLoopOp==OP_PrevIfOpen);
-          VdbeCoverageIf(v, pIn->eEndLoopOp==OP_NextIfOpen);
+          VdbeCoverageIf(v, pIn->eEndLoopOp==OP_Prev);
+          VdbeCoverageIf(v, pIn->eEndLoopOp==OP_Next);
         }
         sqlite3VdbeJumpHere(v, pIn->addrInTop-1);
       }
diff --git a/src/whereInt.h b/src/whereInt.h
index 4b6213af3..5028793bb 100644
--- a/src/whereInt.h
+++ b/src/whereInt.h
@@ -82,6 +82,8 @@ struct WhereLevel {
       struct InLoop {
         int iCur;              /* The VDBE cursor used by this IN operator */
         int addrInTop;         /* Top of the IN loop */
+        int iBase;             /* Base register of multi-key index record */
+        int nPrefix;           /* Number of prior entires in the key */
         u8 eEndLoopOp;         /* IN Loop terminator. OP_Next or OP_Prev */
       } *aInLoop;           /* Information about each nested IN operator */
     } in;                 /* Used when pWLoop->wsFlags&WHERE_IN_ABLE */
@@ -555,3 +557,4 @@ void sqlite3WhereTabFuncArgs(Parse*, struct SrcList_item*, WhereClause*);
 #define WHERE_SKIPSCAN     0x00008000  /* Uses the skip-scan algorithm */
 #define WHERE_UNQ_WANTED   0x00010000  /* WHERE_ONEROW would have been helpful*/
 #define WHERE_PARTIALIDX   0x00020000  /* The automatic index is partial */
+#define WHERE_IN_EARLYOUT  0x00040000  /* Perhaps quit IN loops early */
diff --git a/src/wherecode.c b/src/wherecode.c
index c9edab7b0..67f5e3073 100644
--- a/src/wherecode.c
+++ b/src/wherecode.c
@@ -591,7 +591,14 @@ static int codeEqualityTerm(
           sqlite3VdbeAddOp1(v, OP_IsNull, iOut); VdbeCoverage(v);
           if( i==iEq ){
             pIn->iCur = iTab;
-            pIn->eEndLoopOp = bRev ? OP_PrevIfOpen : OP_NextIfOpen;
+            pIn->eEndLoopOp = bRev ? OP_Prev : OP_Next;
+            if( iEq>0 && (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0 ){
+              pIn->iBase = iReg - i;
+              pIn->nPrefix = i;
+              pLoop->wsFlags |= WHERE_IN_EARLYOUT;
+            }else{
+              pIn->nPrefix = 0;
+            }
           }else{
             pIn->eEndLoopOp = OP_Noop;
           }
@@ -1658,6 +1665,9 @@ Bitmask sqlite3WhereCodeOneLoopStart(
       ** above has already left the cursor sitting on the correct row,
       ** so no further seeking is needed */
     }else{
+      if( pLoop->wsFlags & WHERE_IN_EARLYOUT ){
+        sqlite3VdbeAddOp1(v, OP_SeekHit, iIdxCur);
+      }
       op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev];
       assert( op!=0 );
       sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
@@ -1721,6 +1731,10 @@ Bitmask sqlite3WhereCodeOneLoopStart(
       testcase( op==OP_IdxLE );  VdbeCoverageIf(v, op==OP_IdxLE );
     }
 
+    if( pLoop->wsFlags & WHERE_IN_EARLYOUT ){
+      sqlite3VdbeAddOp2(v, OP_SeekHit, iIdxCur, 1);
+    }
+
     /* Seek the table cursor, if required */
     if( omitTable ){
       /* pIdx is a covering index.  No need to access the main table. */