Index: Makefile.in
==================================================================
--- Makefile.in
+++ Makefile.in
@@ -357,10 +357,11 @@
   $(TOP)/src/test8.c \
   $(TOP)/src/test9.c \
   $(TOP)/src/test_autoext.c \
   $(TOP)/src/test_async.c \
   $(TOP)/src/test_backup.c \
+  $(TOP)/src/test_blob.c \
   $(TOP)/src/test_btree.c \
   $(TOP)/src/test_config.c \
   $(TOP)/src/test_demovfs.c \
   $(TOP)/src/test_devsym.c \
   $(TOP)/src/test_fs.c \

Index: Makefile.msc
==================================================================
--- Makefile.msc
+++ Makefile.msc
@@ -826,10 +826,11 @@
   $(TOP)\src\test8.c \
   $(TOP)\src\test9.c \
   $(TOP)\src\test_autoext.c \
   $(TOP)\src\test_async.c \
   $(TOP)\src\test_backup.c \
+  $(TOP)\src\test_blob.c \
   $(TOP)\src\test_btree.c \
   $(TOP)\src\test_config.c \
   $(TOP)\src\test_demovfs.c \
   $(TOP)\src\test_devsym.c \
   $(TOP)\src\test_fs.c \

Index: ext/fts3/fts3_porter.c
==================================================================
--- ext/fts3/fts3_porter.c
+++ ext/fts3/fts3_porter.c
@@ -181,11 +181,11 @@
 ** Return true if the m-value for z is 1 or more.  In other words,
 ** return true if z contains at least one vowel that is followed
 ** by a consonant.
 **
 ** In this routine z[] is in reverse order.  So we are really looking
-** for an instance of of a consonant followed by a vowel.
+** for an instance of a consonant followed by a vowel.
 */
 static int m_gt_0(const char *z){
   while( isVowel(z) ){ z++; }
   if( *z==0 ) return 0;
   while( isConsonant(z) ){ z++; }

Index: ext/misc/eval.c
==================================================================
--- ext/misc/eval.c
+++ ext/misc/eval.c
@@ -19,15 +19,15 @@
 
 /*
 ** Structure used to accumulate the output
 */
 struct EvalResult {
-  char *z;            /* Accumulated output */
-  const char *zSep;   /* Separator */
-  int szSep;          /* Size of the separator string */
-  int nAlloc;         /* Number of bytes allocated for z[] */
-  int nUsed;          /* Number of bytes of z[] actually used */
+  char *z;               /* Accumulated output */
+  const char *zSep;      /* Separator */
+  int szSep;             /* Size of the separator string */
+  sqlite3_int64 nAlloc;  /* Number of bytes allocated for z[] */
+  sqlite3_int64 nUsed;   /* Number of bytes of z[] actually used */
 };
 
 /*
 ** Callback from sqlite_exec() for the eval() function.
 */
@@ -35,14 +35,17 @@
   struct EvalResult *p = (struct EvalResult*)pCtx;
   int i; 
   for(i=0; i<argc; i++){
     const char *z = argv[i] ? argv[i] : "";
     size_t sz = strlen(z);
-    if( sz+p->nUsed+p->szSep+1 > p->nAlloc ){
+    if( (sqlite3_int64)sz+p->nUsed+p->szSep+1 > p->nAlloc ){
       char *zNew;
       p->nAlloc = p->nAlloc*2 + sz + p->szSep + 1;
-      zNew = sqlite3_realloc(p->z, p->nAlloc);
+      /* Using sqlite3_realloc64() would be better, but it is a recent
+      ** addition and will cause a segfault if loaded by an older version
+      ** of SQLite.  */
+      zNew = p->nAlloc<=0x7fffffff ? sqlite3_realloc(p->z, (int)p->nAlloc) : 0;
       if( zNew==0 ){
         sqlite3_free(p->z);
         memset(p, 0, sizeof(*p));
         return 1;
       }
@@ -91,11 +94,11 @@
     sqlite3_free(zErr);
   }else if( x.zSep==0 ){
     sqlite3_result_error_nomem(context);
     sqlite3_free(x.z);
   }else{
-    sqlite3_result_text(context, x.z, x.nUsed, sqlite3_free);
+    sqlite3_result_text(context, x.z, (int)x.nUsed, sqlite3_free);
   }
 }
 
 
 #ifdef _WIN32

Index: src/analyze.c
==================================================================
--- src/analyze.c
+++ src/analyze.c
@@ -1436,12 +1436,10 @@
 
 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
   if( z==0 ) z = "";
 #else
   assert( z!=0 );
-  pIndex->bUnordered = 0;
-  pIndex->noSkipScan = 0;
 #endif
   for(i=0; *z && i<nOut; i++){
     v = 0;
     while( (c=z[0])>='0' && c<='9' ){
       v = v*10 + c - '0';
@@ -1457,29 +1455,32 @@
     aLog[i] = sqlite3LogEst(v);
 #endif
     if( *z==' ' ) z++;
   }
 #ifndef SQLITE_ENABLE_STAT3_OR_STAT4
-  assert( pIndex!=0 );
+  assert( pIndex!=0 ); {
 #else
-  if( pIndex )
+  if( pIndex ){
 #endif
-  while( z[0] ){
-    if( sqlite3_strglob("unordered*", z)==0 ){
-      pIndex->bUnordered = 1;
-    }else if( sqlite3_strglob("sz=[0-9]*", z)==0 ){
-      pIndex->szIdxRow = sqlite3LogEst(sqlite3Atoi(z+3));
-    }else if( sqlite3_strglob("noskipscan*", z)==0 ){
-      pIndex->noSkipScan = 1;
-    }
+    pIndex->bUnordered = 0;
+    pIndex->noSkipScan = 0;
+    while( z[0] ){
+      if( sqlite3_strglob("unordered*", z)==0 ){
+        pIndex->bUnordered = 1;
+      }else if( sqlite3_strglob("sz=[0-9]*", z)==0 ){
+        pIndex->szIdxRow = sqlite3LogEst(sqlite3Atoi(z+3));
+      }else if( sqlite3_strglob("noskipscan*", z)==0 ){
+        pIndex->noSkipScan = 1;
+      }
 #ifdef SQLITE_ENABLE_COSTMULT
-    else if( sqlite3_strglob("costmult=[0-9]*",z)==0 ){
-      pIndex->pTable->costMult = sqlite3LogEst(sqlite3Atoi(z+9));
-    }
+      else if( sqlite3_strglob("costmult=[0-9]*",z)==0 ){
+        pIndex->pTable->costMult = sqlite3LogEst(sqlite3Atoi(z+9));
+      }
 #endif
-    while( z[0]!=0 && z[0]!=' ' ) z++;
-    while( z[0]==' ' ) z++;
+      while( z[0]!=0 && z[0]!=' ' ) z++;
+      while( z[0]==' ' ) z++;
+    }
   }
 }
 
 /*
 ** This callback is invoked once for each index when reading the
@@ -1593,11 +1594,11 @@
       tRowcnt avgEq = 0;
       tRowcnt nRow;             /* Number of rows in index */
       i64 nSum100 = 0;          /* Number of terms contributing to sumEq */
       i64 nDist100;             /* Number of distinct values in index */
 
-      if( pIdx->aiRowEst==0 || pIdx->aiRowEst[iCol+1]==0 ){
+      if( !pIdx->aiRowEst || iCol>=pIdx->nKeyCol || pIdx->aiRowEst[iCol+1]==0 ){
         nRow = pFinal->anLt[iCol];
         nDist100 = (i64)100 * pFinal->anDLt[iCol];
         nSample--;
       }else{
         nRow = pIdx->aiRowEst[0];

Index: src/btree.c
==================================================================
--- src/btree.c
+++ src/btree.c
@@ -1355,11 +1355,11 @@
   ** to see if defragmentation is necessary.
   */
   testcase( gap+2+nByte==top );
   if( gap+2+nByte>top ){
  defragment_page:
-    testcase( pPage->nCell==0 );
+    assert( pPage->nCell>0 || CORRUPT_DB );
     rc = defragmentPage(pPage);
     if( rc ) return rc;
     top = get2byteNotZero(&data[hdr+5]);
     assert( gap+nByte<=top );
   }
@@ -6256,10 +6256,18 @@
   }
   return nRet;
 }
 
 /*
+** apCell[] and szCell[] contains pointers to and sizes of all cells in the
+** pages being balanced.  The current page, pPg, has pPg->nCell cells starting
+** with apCell[iOld].  After balancing, this page should hold nNew cells
+** starting at apCell[iNew].
+**
+** This routine makes the necessary adjustments to pPg so that it contains
+** the correct cells after being balanced.
+**
 ** The pPg->nFree field is invalid when this function returns. It is the
 ** responsibility of the caller to set it correctly.
 */
 static void editPage(
   MemPage *pPg,                   /* Edit this page */
@@ -6296,16 +6304,17 @@
     nCell -= pageFreeArray(
         pPg, iOldEnd-iNewEnd, &apCell[iNewEnd], &szCell[iNewEnd]
     );
   }
 
-  pData = &aData[get2byte(&aData[hdr+5])];
+  pData = &aData[get2byteNotZero(&aData[hdr+5])];
   if( pData<pBegin ) goto editpage_fail;
 
   /* Add cells to the start of the page */
   if( iNew<iOld ){
-    int nAdd = iOld-iNew;
+    int nAdd = MIN(nNew,iOld-iNew);
+    assert( (iOld-iNew)<nNew || nCell==0 || CORRUPT_DB );
     pCellptr = pPg->aCellIdx;
     memmove(&pCellptr[nAdd*2], pCellptr, nCell*2);
     if( pageInsertArray(
           pPg, pBegin, &pData, pCellptr,
           nAdd, &apCell[iNew], &szCell[iNew]
@@ -6406,11 +6415,11 @@
   assert( sqlite3_mutex_held(pPage->pBt->mutex) );
   assert( sqlite3PagerIswriteable(pParent->pDbPage) );
   assert( pPage->nOverflow==1 );
 
   /* This error condition is now caught prior to reaching this function */
-  if( pPage->nCell==0 ) return SQLITE_CORRUPT_BKPT;
+  if( NEVER(pPage->nCell==0) ) return SQLITE_CORRUPT_BKPT;
 
   /* Allocate a new page. This page will become the right-sibling of 
   ** pPage. Make the parent page writable, so that the new divider cell
   ** may be inserted. If both these operations are successful, proceed.
   */
@@ -6849,11 +6858,15 @@
         ** pointer of the divider cell */
         memcpy(apCell[nCell], &pOld->aData[8], 4);
       }else{
         assert( leafCorrection==4 );
         if( szCell[nCell]<4 ){
-          /* Do not allow any cells smaller than 4 bytes. */
+          /* Do not allow any cells smaller than 4 bytes. If a smaller cell
+          ** does exist, pad it with 0x00 bytes. */
+          assert( szCell[nCell]==3 );
+          assert( apCell[nCell]==&pTemp[iSpace1-3] );
+          pTemp[iSpace1++] = 0x00;
           szCell[nCell] = 4;
         }
       }
       nCell++;
     }
@@ -7084,11 +7097,15 @@
       ** was either part of sibling page iOld (possibly an overflow cell), 
       ** or else the divider cell to the left of sibling page iOld. So,
       ** if sibling page iOld had the same page number as pNew, and if
       ** pCell really was a part of sibling page iOld (not a divider or
       ** overflow cell), we can skip updating the pointer map entries.  */
-      if( pNew->pgno!=aPgno[iOld] || pCell<aOld || pCell>=&aOld[usableSize] ){
+      if( iOld>=nNew
+       || pNew->pgno!=aPgno[iOld]
+       || pCell<aOld
+       || pCell>=&aOld[usableSize]
+      ){
         if( !leafCorrection ){
           ptrmapPut(pBt, get4byte(pCell), PTRMAP_BTREE, pNew->pgno, &rc);
         }
         if( szCell[i]>pNew->minLocal ){
           ptrmapPutOvflPtr(pNew, pCell, &rc);

Index: src/expr.c
==================================================================
--- src/expr.c
+++ src/expr.c
@@ -1412,11 +1412,12 @@
     case TK_FLOAT:
     case TK_BLOB:
       return 0;
     case TK_COLUMN:
       assert( p->pTab!=0 );
-      return p->iColumn>=0 && p->pTab->aCol[p->iColumn].notNull==0;
+      return ExprHasProperty(p, EP_CanBeNull) ||
+             (p->iColumn>=0 && p->pTab->aCol[p->iColumn].notNull==0);
     default:
       return 1;
   }
 }
 

Index: src/main.c
==================================================================
--- src/main.c
+++ src/main.c
@@ -1030,10 +1030,18 @@
 
   /* Close all database connections */
   for(j=0; j<db->nDb; j++){
     struct Db *pDb = &db->aDb[j];
     if( pDb->pBt ){
+      if( pDb->pSchema ){
+        /* Must clear the KeyInfo cache.  See ticket [e4a18565a36884b00edf] */
+        for(i=sqliteHashFirst(&pDb->pSchema->idxHash); i; i=sqliteHashNext(i)){
+          Index *pIdx = sqliteHashData(i);
+          sqlite3KeyInfoUnref(pIdx->pKeyInfo);
+          pIdx->pKeyInfo = 0;
+        }
+      }
       sqlite3BtreeClose(pDb->pBt);
       pDb->pBt = 0;
       if( j!=1 ){
         pDb->pSchema = 0;
       }
@@ -1934,14 +1942,17 @@
 
   /* Initialize the output variables to -1 in case an error occurs. */
   if( pnLog ) *pnLog = -1;
   if( pnCkpt ) *pnCkpt = -1;
 
-  assert( SQLITE_CHECKPOINT_FULL>SQLITE_CHECKPOINT_PASSIVE );
-  assert( SQLITE_CHECKPOINT_FULL<SQLITE_CHECKPOINT_RESTART );
-  assert( SQLITE_CHECKPOINT_PASSIVE+2==SQLITE_CHECKPOINT_RESTART );
-  if( eMode<SQLITE_CHECKPOINT_PASSIVE || eMode>SQLITE_CHECKPOINT_RESTART ){
+  assert( SQLITE_CHECKPOINT_PASSIVE==0 );
+  assert( SQLITE_CHECKPOINT_FULL==1 );
+  assert( SQLITE_CHECKPOINT_RESTART==2 );
+  assert( SQLITE_CHECKPOINT_TRUNCATE==3 );
+  if( eMode<SQLITE_CHECKPOINT_PASSIVE || eMode>SQLITE_CHECKPOINT_TRUNCATE ){
+    /* EVIDENCE-OF: R-03996-12088 The M parameter must be a valid checkpoint
+    ** mode: */
     return SQLITE_MISUSE;
   }
 
   sqlite3_mutex_enter(db->mutex);
   if( zDb && zDb[0] ){
@@ -1992,11 +2003,13 @@
 ** Checkpoint database zDb. If zDb is NULL, or if the buffer zDb points
 ** to contains a zero-length string, all attached databases are 
 ** checkpointed.
 */
 int sqlite3_wal_checkpoint(sqlite3 *db, const char *zDb){
-  return sqlite3_wal_checkpoint_v2(db, zDb, SQLITE_CHECKPOINT_PASSIVE, 0, 0);
+  /* EVIDENCE-OF: R-41613-20553 The sqlite3_wal_checkpoint(D,X) is equivalent to
+  ** sqlite3_wal_checkpoint_v2(D,X,SQLITE_CHECKPOINT_PASSIVE,0,0). */
+  return sqlite3_wal_checkpoint_v2(db,zDb,SQLITE_CHECKPOINT_PASSIVE,0,0);
 }
 
 #ifndef SQLITE_OMIT_WAL
 /*
 ** Run a checkpoint on database iDb. This is a no-op if database iDb is

Index: src/pager.c
==================================================================
--- src/pager.c
+++ src/pager.c
@@ -7119,11 +7119,12 @@
 */
 int sqlite3PagerCheckpoint(Pager *pPager, int eMode, int *pnLog, int *pnCkpt){
   int rc = SQLITE_OK;
   if( pPager->pWal && PagerOtaMode(pPager)==0 ){
     rc = sqlite3WalCheckpoint(pPager->pWal, eMode,
-        pPager->xBusyHandler, pPager->pBusyHandlerArg,
+        (eMode==SQLITE_CHECKPOINT_PASSIVE ? 0 : pPager->xBusyHandler),
+        pPager->pBusyHandlerArg,
         pPager->ckptSyncFlags, pPager->pageSize, (u8 *)pPager->pTmpSpace,
         pnLog, pnCkpt
     );
   }
   return rc;

Index: src/pragma.c
==================================================================
--- src/pragma.c
+++ src/pragma.c
@@ -2255,11 +2255,11 @@
   break;
 #endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */
 
 #ifndef SQLITE_OMIT_WAL
   /*
-  **   PRAGMA [database.]wal_checkpoint = passive|full|restart
+  **   PRAGMA [database.]wal_checkpoint = passive|full|restart|truncate
   **
   ** Checkpoint the database.
   */
   case PragTyp_WAL_CHECKPOINT: {
     int iBt = (pId2->z?iDb:SQLITE_MAX_ATTACHED);
@@ -2267,10 +2267,12 @@
     if( zRight ){
       if( sqlite3StrICmp(zRight, "full")==0 ){
         eMode = SQLITE_CHECKPOINT_FULL;
       }else if( sqlite3StrICmp(zRight, "restart")==0 ){
         eMode = SQLITE_CHECKPOINT_RESTART;
+      }else if( sqlite3StrICmp(zRight, "truncate")==0 ){
+        eMode = SQLITE_CHECKPOINT_TRUNCATE;
       }
     }
     sqlite3VdbeSetNumCols(v, 3);
     pParse->nMem = 3;
     sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "busy", SQLITE_STATIC);

Index: src/resolve.c
==================================================================
--- src/resolve.c
+++ src/resolve.c
@@ -318,10 +318,14 @@
         }
       }
       if( pMatch ){
         pExpr->iTable = pMatch->iCursor;
         pExpr->pTab = pMatch->pTab;
+        assert( (pMatch->jointype & JT_RIGHT)==0 ); /* RIGHT JOIN not (yet) supported */
+        if( (pMatch->jointype & JT_LEFT)!=0 ){
+          ExprSetProperty(pExpr, EP_CanBeNull);
+        }
         pSchema = pExpr->pTab->pSchema;
       }
     } /* if( pSrcList ) */
 
 #ifndef SQLITE_OMIT_TRIGGER

Index: src/select.c
==================================================================
--- src/select.c
+++ src/select.c
@@ -4827,11 +4827,11 @@
   **
   **     SELECT DISTINCT xyz FROM ... ORDER BY xyz
   **
   ** is transformed to:
   **
-  **     SELECT xyz FROM ... GROUP BY xyz
+  **     SELECT xyz FROM ... GROUP BY xyz ORDER BY xyz
   **
   ** The second form is preferred as a single index (or temp-table) may be 
   ** used for both the ORDER BY and DISTINCT processing. As originally 
   ** written the query must use a temp-table for at least one of the ORDER 
   ** BY and DISTINCT, and an index or separate temp-table for the other.
@@ -4840,11 +4840,10 @@
    && sqlite3ExprListCompare(sSort.pOrderBy, p->pEList, -1)==0
   ){
     p->selFlags &= ~SF_Distinct;
     p->pGroupBy = sqlite3ExprListDup(db, p->pEList, 0);
     pGroupBy = p->pGroupBy;
-    sSort.pOrderBy = 0;
     /* Notice that even thought SF_Distinct has been cleared from p->selFlags,
     ** the sDistinct.isTnct is still set.  Hence, isTnct represents the
     ** original setting of the SF_Distinct flag, not the current setting */
     assert( sDistinct.isTnct );
   }

Index: src/shell.c
==================================================================
--- src/shell.c
+++ src/shell.c
@@ -4036,14 +4036,16 @@
 
 int main(int argc, char **argv){
   char *zErrMsg = 0;
   ShellState data;
   const char *zInitFile = 0;
-  char *zFirstCmd = 0;
   int i;
   int rc = 0;
   int warnInmemoryDb = 0;
+  int readStdin = 1;
+  int nCmd = 0;
+  char **azCmd = 0;
 
 #if USE_SYSTEM_SQLITE+0!=1
   if( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)!=0 ){
     fprintf(stderr, "SQLite header and source version mismatch\n%s\n%s\n",
             sqlite3_sourceid(), SQLITE_SOURCE_ID);
@@ -4058,10 +4060,22 @@
   ** else is done.
   */
 #ifdef SIGINT
   signal(SIGINT, interrupt_handler);
 #endif
+
+#ifdef SQLITE_SHELL_DBNAME_PROC
+  {
+    /* If the SQLITE_SHELL_DBNAME_PROC macro is defined, then it is the name
+    ** of a C-function that will provide the name of the database file.  Use
+    ** this compile-time option to embed this shell program in larger
+    ** applications. */
+    extern void SQLITE_SHELL_DBNAME_PROC(const char**);
+    SQLITE_SHELL_DBNAME_PROC(&data.zDbFilename);
+    warnInmemoryDb = 0;
+  }
+#endif
 
   /* Do an initial pass through the command-line argument to locate
   ** the name of the database file, the name of the initialization file,
   ** the size of the alternative malloc heap,
   ** and the first command to execute.
@@ -4070,19 +4084,22 @@
     char *z;
     z = argv[i];
     if( z[0]!='-' ){
       if( data.zDbFilename==0 ){
         data.zDbFilename = z;
-        continue;
-      }
-      if( zFirstCmd==0 ){
-        zFirstCmd = z;
-        continue;
-      }
-      fprintf(stderr,"%s: Error: too many options: \"%s\"\n", Argv0, argv[i]);
-      fprintf(stderr,"Use -help for a list of options.\n");
-      return 1;
+      }else{
+        /* Excesss arguments are interpreted as SQL (or dot-commands) and
+        ** mean that nothing is read from stdin */
+        readStdin = 0;
+        nCmd++;
+        azCmd = realloc(azCmd, sizeof(azCmd[0])*nCmd);
+        if( azCmd==0 ){
+          fprintf(stderr, "out of memory\n");
+          exit(1);
+        }
+        azCmd[nCmd-1] = z;
+      }
     }
     if( z[1]=='-' ) z++;
     if( strcmp(z,"-separator")==0
      || strcmp(z,"-nullvalue")==0
      || strcmp(z,"-newline")==0
@@ -4169,15 +4186,10 @@
     warnInmemoryDb = argc==1;
 #else
     fprintf(stderr,"%s: Error: no database filename specified\n", Argv0);
     return 1;
 #endif
-#ifdef SQLITE_SHELL_DBNAME_PROC
-    { extern void SQLITE_SHELL_DBNAME_PROC(const char**);
-      SQLITE_SHELL_DBNAME_PROC(&data.zDbFilename);
-      warnInmemoryDb = 0; }
-#endif
   }
   data.out = stdout;
 
   /* Go ahead and open the database file if it already exists.  If the
   ** file does not exist, delay opening it.  This prevents empty database
@@ -4270,10 +4282,14 @@
       i++;
 #endif
     }else if( strcmp(z,"-help")==0 ){
       usage(1);
     }else if( strcmp(z,"-cmd")==0 ){
+      /* Run commands that follow -cmd first and separately from commands
+      ** that simply appear on the command-line.  This seems goofy.  It would
+      ** be better if all commands ran in the order that they appear.  But
+      ** we retain the goofy behavior for historical compatibility. */
       if( i==argc-1 ) break;
       z = cmdline_option_value(argc,argv,++i);
       if( z[0]=='.' ){
         rc = do_meta_command(z, &data);
         if( rc && bail_on_error ) return rc==2 ? 0 : rc;
@@ -4293,27 +4309,32 @@
       fprintf(stderr,"Use -help for a list of options.\n");
       return 1;
     }
   }
 
-  if( zFirstCmd ){
-    /* Run just the command that follows the database name
-    */
-    if( zFirstCmd[0]=='.' ){
-      rc = do_meta_command(zFirstCmd, &data);
-      if( rc==2 ) rc = 0;
-    }else{
-      open_db(&data, 0);
-      rc = shell_exec(data.db, zFirstCmd, shell_callback, &data, &zErrMsg);
-      if( zErrMsg!=0 ){
-        fprintf(stderr,"Error: %s\n", zErrMsg);
-        return rc!=0 ? rc : 1;
-      }else if( rc!=0 ){
-        fprintf(stderr,"Error: unable to process SQL \"%s\"\n", zFirstCmd);
-        return rc;
-      }
-    }
+  if( !readStdin ){
+    /* Run all arguments that do not begin with '-' as if they were separate
+    ** command-line inputs, except for the argToSkip argument which contains
+    ** the database filename.
+    */
+    for(i=0; i<nCmd; i++){
+      if( azCmd[i][0]=='.' ){
+        rc = do_meta_command(azCmd[i], &data);
+        if( rc ) return rc==2 ? 0 : rc;
+      }else{
+        open_db(&data, 0);
+        rc = shell_exec(data.db, azCmd[i], shell_callback, &data, &zErrMsg);
+        if( zErrMsg!=0 ){
+          fprintf(stderr,"Error: %s\n", zErrMsg);
+          return rc!=0 ? rc : 1;
+        }else if( rc!=0 ){
+          fprintf(stderr,"Error: unable to process SQL: %s\n", azCmd[i]);
+          return rc;
+        }
+      }
+    }
+    free(azCmd);
   }else{
     /* Run commands received from standard input
     */
     if( stdin_is_interactive ){
       char *zHome;

Index: src/sqlite.h.in
==================================================================
--- src/sqlite.h.in
+++ src/sqlite.h.in
@@ -1219,11 +1219,11 @@
 ** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED
 ** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE
 ** </ul>
 **
 ** When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as
-** was given no the corresponding lock.  
+** was given on the corresponding lock.  
 **
 ** The xShmLock method can transition between unlocked and SHARED or
 ** between unlocked and EXCLUSIVE.  It cannot transition between SHARED
 ** and EXCLUSIVE.
 */
@@ -1522,12 +1522,12 @@
 ** tracks memory usage, for example. </dd>
 **
 ** [[SQLITE_CONFIG_MEMSTATUS]] <dt>SQLITE_CONFIG_MEMSTATUS</dt>
 ** <dd> ^The SQLITE_CONFIG_MEMSTATUS option takes single argument of type int,
 ** interpreted as a boolean, which enables or disables the collection of
-** memory allocation statistics. ^(When memory allocation statistics are disabled, the 
-** following SQLite interfaces become non-operational:
+** memory allocation statistics. ^(When memory allocation statistics are
+** disabled, the following SQLite interfaces become non-operational:
 **   <ul>
 **   <li> [sqlite3_memory_used()]
 **   <li> [sqlite3_memory_highwater()]
 **   <li> [sqlite3_soft_heap_limit64()]
 **   <li> [sqlite3_status()]
@@ -1564,11 +1564,12 @@
 ** that SQLite can use for the database page cache with the default page
 ** cache implementation.  
 ** This configuration should not be used if an application-define page
 ** cache implementation is loaded using the [SQLITE_CONFIG_PCACHE2]
 ** configuration option.
-** ^There are three arguments to SQLITE_CONFIG_PAGECACHE: A pointer to 8-byte aligned
+** ^There are three arguments to SQLITE_CONFIG_PAGECACHE: A pointer to
+** 8-byte aligned
 ** memory, the size of each page buffer (sz), and the number of pages (N).
 ** The sz argument should be the size of the largest database page
 ** (a power of two between 512 and 32768) plus some extra bytes for each
 ** page header.  ^The number of extra bytes needed by the page header
 ** can be determined using the [SQLITE_CONFIG_PCACHE_HDRSZ] option 
@@ -1584,11 +1585,12 @@
 ** SQLite goes to [sqlite3_malloc()] for the additional storage space.</dd>
 **
 ** [[SQLITE_CONFIG_HEAP]] <dt>SQLITE_CONFIG_HEAP</dt>
 ** <dd> ^The SQLITE_CONFIG_HEAP option specifies a static memory buffer 
 ** that SQLite will use for all of its dynamic memory allocation needs
-** beyond those provided for by [SQLITE_CONFIG_SCRATCH] and [SQLITE_CONFIG_PAGECACHE].
+** beyond those provided for by [SQLITE_CONFIG_SCRATCH] and
+** [SQLITE_CONFIG_PAGECACHE].
 ** ^The SQLITE_CONFIG_HEAP option is only available if SQLite is compiled
 ** with either [SQLITE_ENABLE_MEMSYS3] or [SQLITE_ENABLE_MEMSYS5] and returns
 ** [SQLITE_ERROR] if invoked otherwise.
 ** ^There are three arguments to SQLITE_CONFIG_HEAP:
 ** An 8-byte aligned pointer to the memory,
@@ -1604,13 +1606,13 @@
 ** for the minimum allocation size are 2**5 through 2**8.</dd>
 **
 ** [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt>
 ** <dd> ^(The SQLITE_CONFIG_MUTEX option takes a single argument which is a
 ** pointer to an instance of the [sqlite3_mutex_methods] structure.
-** The argument specifies alternative low-level mutex routines to be used in place
-** the mutex routines built into SQLite.)^  ^SQLite makes a copy of the
-** content of the [sqlite3_mutex_methods] structure before the call to
+** The argument specifies alternative low-level mutex routines to be used
+** in place the mutex routines built into SQLite.)^  ^SQLite makes a copy of
+** the content of the [sqlite3_mutex_methods] structure before the call to
 ** [sqlite3_config()] returns. ^If SQLite is compiled with
 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
 ** the entire mutexing subsystem is omitted from the build and hence calls to
 ** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will
 ** return [SQLITE_ERROR].</dd>
@@ -1644,12 +1646,12 @@
 ** the interface to a custom page cache implementation.)^
 ** ^SQLite makes a copy of the [sqlite3_pcache_methods2] object.</dd>
 **
 ** [[SQLITE_CONFIG_GETPCACHE2]] <dt>SQLITE_CONFIG_GETPCACHE2</dt>
 ** <dd> ^(The SQLITE_CONFIG_GETPCACHE2 option takes a single argument which
-** is a pointer to an [sqlite3_pcache_methods2] object.  SQLite copies of the current
-** page cache implementation into that object.)^ </dd>
+** is a pointer to an [sqlite3_pcache_methods2] object.  SQLite copies of
+** the current page cache implementation into that object.)^ </dd>
 **
 ** [[SQLITE_CONFIG_LOG]] <dt>SQLITE_CONFIG_LOG</dt>
 ** <dd> The SQLITE_CONFIG_LOG option is used to configure the SQLite
 ** global [error log].
 ** (^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
@@ -1670,12 +1672,13 @@
 ** function must be threadsafe. </dd>
 **
 ** [[SQLITE_CONFIG_URI]] <dt>SQLITE_CONFIG_URI
 ** <dd>^(The SQLITE_CONFIG_URI option takes a single argument of type int.
 ** If non-zero, then URI handling is globally enabled. If the parameter is zero,
-** then URI handling is globally disabled.)^ ^If URI handling is globally enabled,
-** all filenames passed to [sqlite3_open()], [sqlite3_open_v2()], [sqlite3_open16()] or
+** then URI handling is globally disabled.)^ ^If URI handling is globally
+** enabled, all filenames passed to [sqlite3_open()], [sqlite3_open_v2()],
+** [sqlite3_open16()] or
 ** specified as part of [ATTACH] commands are interpreted as URIs, regardless
 ** of whether or not the [SQLITE_OPEN_URI] flag is set when the database
 ** connection is opened. ^If it is globally disabled, filenames are
 ** only interpreted as URIs if the SQLITE_OPEN_URI flag is set when the
 ** database connection is opened. ^(By default, URI handling is globally
@@ -1733,21 +1736,21 @@
 ** changed to its compile-time default.
 **
 ** [[SQLITE_CONFIG_WIN32_HEAPSIZE]]
 ** <dt>SQLITE_CONFIG_WIN32_HEAPSIZE
 ** <dd>^The SQLITE_CONFIG_WIN32_HEAPSIZE option is only available if SQLite is
-** compiled for Windows with the [SQLITE_WIN32_MALLOC] pre-processor macro defined.
-** ^SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit unsigned integer value
+** compiled for Windows with the [SQLITE_WIN32_MALLOC] pre-processor macro
+** defined. ^SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit unsigned integer value
 ** that specifies the maximum size of the created heap.
 ** </dl>
 **
 ** [[SQLITE_CONFIG_PCACHE_HDRSZ]]
 ** <dt>SQLITE_CONFIG_PCACHE_HDRSZ
 ** <dd>^The SQLITE_CONFIG_PCACHE_HDRSZ option takes a single parameter which
 ** is a pointer to an integer and writes into that integer the number of extra
-** bytes per page required for each page in [SQLITE_CONFIG_PAGECACHE]. The amount of
-** extra space required can change depending on the compiler,
+** bytes per page required for each page in [SQLITE_CONFIG_PAGECACHE].
+** The amount of extra space required can change depending on the compiler,
 ** target platform, and SQLite version.
 ** </dl>
 */
 #define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
 #define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
@@ -2047,10 +2050,11 @@
 int sqlite3_complete(const char *sql);
 int sqlite3_complete16(const void *sql);
 
 /*
 ** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors
+** KEYWORDS: {busy-handler callback} {busy handler}
 **
 ** ^The sqlite3_busy_handler(D,X,P) routine sets a callback function X
 ** that might be invoked with argument P whenever
 ** an attempt is made to access a database table associated with
 ** [database connection] D when another thread
@@ -2063,11 +2067,11 @@
 ** is not NULL, then the callback might be invoked with two arguments.
 **
 ** ^The first argument to the busy handler is a copy of the void* pointer which
 ** is the third argument to sqlite3_busy_handler().  ^The second argument to
 ** the busy handler callback is the number of times that the busy handler has
-** been invoked for the same locking event.  ^If the
+** been invoked previously for the same locking event.  ^If the
 ** busy callback returns 0, then no additional attempts are made to
 ** access the database and [SQLITE_BUSY] is returned
 ** to the application.
 ** ^If the callback returns non-zero, then another attempt
 ** is made to access the database and the cycle repeats.
@@ -4518,11 +4522,12 @@
 ** If these routines are called from within the different thread
 ** than the one containing the application-defined function that received
 ** the [sqlite3_context] pointer, the results are undefined.
 */
 void sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*));
-void sqlite3_result_blob64(sqlite3_context*,const void*,sqlite3_uint64,void(*)(void*));
+void sqlite3_result_blob64(sqlite3_context*,const void*,
+                           sqlite3_uint64,void(*)(void*));
 void sqlite3_result_double(sqlite3_context*, double);
 void sqlite3_result_error(sqlite3_context*, const char*, int);
 void sqlite3_result_error16(sqlite3_context*, const void*, int);
 void sqlite3_result_error_toobig(sqlite3_context*);
 void sqlite3_result_error_nomem(sqlite3_context*);
@@ -7244,101 +7249,118 @@
 int sqlite3_wal_autocheckpoint(sqlite3 *db, int N);
 
 /*
 ** CAPI3REF: Checkpoint a database
 **
-** ^The [sqlite3_wal_checkpoint(D,X)] interface causes database named X
-** on [database connection] D to be [checkpointed].  ^If X is NULL or an
-** empty string, then a checkpoint is run on all databases of
-** connection D.  ^If the database connection D is not in
-** [WAL | write-ahead log mode] then this interface is a harmless no-op.
-** ^The [sqlite3_wal_checkpoint(D,X)] interface initiates a
-** [sqlite3_wal_checkpoint_v2|PASSIVE] checkpoint.
-** Use the [sqlite3_wal_checkpoint_v2()] interface to get a FULL
-** or RESET checkpoint.
-**
-** ^The [wal_checkpoint pragma] can be used to invoke this interface
-** from SQL.  ^The [sqlite3_wal_autocheckpoint()] interface and the
-** [wal_autocheckpoint pragma] can be used to cause this interface to be
-** run whenever the WAL reaches a certain size threshold.
-**
-** See also: [sqlite3_wal_checkpoint_v2()]
+** ^(The sqlite3_wal_checkpoint(D,X) is equivalent to
+** [sqlite3_wal_checkpoint_v2](D,X,[SQLITE_CHECKPOINT_PASSIVE],0,0).)^
+**
+** In brief, sqlite3_wal_checkpoint(D,X) causes the content in the 
+** [write-ahead log] for database X on [database connection] D to be
+** transferred into the database file and for the write-ahead log to
+** be reset.  See the [checkpointing] documentation for addition
+** information.
+**
+** This interface used to be the only way to cause a checkpoint to
+** occur.  But then the newer and more powerful [sqlite3_wal_checkpoint_v2()]
+** interface was added.  This interface is retained for backwards
+** compatibility and as a convenience for applications that need to manually
+** start a callback but which do not need the full power (and corresponding
+** complication) of [sqlite3_wal_checkpoint_v2()].
 */
 int sqlite3_wal_checkpoint(sqlite3 *db, const char *zDb);
 
 /*
 ** CAPI3REF: Checkpoint a database
 **
-** Run a checkpoint operation on WAL database zDb attached to database 
-** handle db. The specific operation is determined by the value of the 
-** eMode parameter:
+** ^(The sqlite3_wal_checkpoint_v2(D,X,M,L,C) interface runs a checkpoint
+** operation on database X of [database connection] D in mode M.  Status
+** information is written back into integers pointed to by L and C.)^
+** ^(The M parameter must be a valid [checkpoint mode]:)^
 **
 ** <dl>
 ** <dt>SQLITE_CHECKPOINT_PASSIVE<dd>
-**   Checkpoint as many frames as possible without waiting for any database 
-**   readers or writers to finish. Sync the db file if all frames in the log
-**   are checkpointed. This mode is the same as calling 
-**   sqlite3_wal_checkpoint(). The [sqlite3_busy_handler|busy-handler callback]
-**   is never invoked.
+**   ^Checkpoint as many frames as possible without waiting for any database 
+**   readers or writers to finish, then sync the database file if all frames 
+**   in the log were checkpointed. ^The [busy-handler callback]
+**   is never invoked in the SQLITE_CHECKPOINT_PASSIVE mode.  
+**   ^On the other hand, passive mode might leave the checkpoint unfinished
+**   if there are concurrent readers or writers.
 **
 ** <dt>SQLITE_CHECKPOINT_FULL<dd>
-**   This mode blocks (it invokes the
+**   ^This mode blocks (it invokes the
 **   [sqlite3_busy_handler|busy-handler callback]) until there is no
 **   database writer and all readers are reading from the most recent database
-**   snapshot. It then checkpoints all frames in the log file and syncs the
-**   database file. This call blocks database writers while it is running,
-**   but not database readers.
+**   snapshot. ^It then checkpoints all frames in the log file and syncs the
+**   database file. ^This mode blocks new database writers while it is pending,
+**   but new database readers are allowed to continue unimpeded.
 **
 ** <dt>SQLITE_CHECKPOINT_RESTART<dd>
-**   This mode works the same way as SQLITE_CHECKPOINT_FULL, except after 
-**   checkpointing the log file it blocks (calls the 
-**   [sqlite3_busy_handler|busy-handler callback])
-**   until all readers are reading from the database file only. This ensures 
-**   that the next client to write to the database file restarts the log file 
-**   from the beginning. This call blocks database writers while it is running,
-**   but not database readers.
+**   ^This mode works the same way as SQLITE_CHECKPOINT_FULL with the addition
+**   that after checkpointing the log file it blocks (calls the 
+**   [busy-handler callback])
+**   until all readers are reading from the database file only. ^This ensures 
+**   that the next writer will restart the log file from the beginning.
+**   ^Like SQLITE_CHECKPOINT_FULL, this mode blocks new
+**   database writer attempts while it is pending, but does not impede readers.
+**
+** <dt>SQLITE_CHECKPOINT_TRUNCATE<dd>
+**   ^This mode works the same way as SQLITE_CHECKPOINT_RESTART with the
+**   addition that it also truncates the log file to zero bytes just prior
+**   to a successful return.
 ** </dl>
 **
-** If pnLog is not NULL, then *pnLog is set to the total number of frames in
-** the log file before returning. If pnCkpt is not NULL, then *pnCkpt is set to
-** the total number of checkpointed frames (including any that were already
-** checkpointed when this function is called). *pnLog and *pnCkpt may be
-** populated even if sqlite3_wal_checkpoint_v2() returns other than SQLITE_OK.
-** If no values are available because of an error, they are both set to -1
-** before returning to communicate this to the caller.
+** ^If pnLog is not NULL, then *pnLog is set to the total number of frames in
+** the log file or to -1 if the checkpoint could not run because
+** of an error or because the database is not in [WAL mode]. ^If pnCkpt is not
+** NULL,then *pnCkpt is set to the total number of checkpointed frames in the
+** log file (including any that were already checkpointed before the function
+** was called) or to -1 if the checkpoint could not run due to an error or
+** because the database is not in WAL mode. ^Note that upon successful
+** completion of an SQLITE_CHECKPOINT_TRUNCATE, the log file will have been
+** truncated to zero bytes and so both *pnLog and *pnCkpt will be set to zero.
 **
-** All calls obtain an exclusive "checkpoint" lock on the database file. If
+** ^All calls obtain an exclusive "checkpoint" lock on the database file. ^If
 ** any other process is running a checkpoint operation at the same time, the 
-** lock cannot be obtained and SQLITE_BUSY is returned. Even if there is a 
+** lock cannot be obtained and SQLITE_BUSY is returned. ^Even if there is a 
 ** busy-handler configured, it will not be invoked in this case.
 **
-** The SQLITE_CHECKPOINT_FULL and RESTART modes also obtain the exclusive 
-** "writer" lock on the database file. If the writer lock cannot be obtained
-** immediately, and a busy-handler is configured, it is invoked and the writer
-** lock retried until either the busy-handler returns 0 or the lock is
-** successfully obtained. The busy-handler is also invoked while waiting for
-** database readers as described above. If the busy-handler returns 0 before
+** ^The SQLITE_CHECKPOINT_FULL, RESTART and TRUNCATE modes also obtain the 
+** exclusive "writer" lock on the database file. ^If the writer lock cannot be
+** obtained immediately, and a busy-handler is configured, it is invoked and
+** the writer lock retried until either the busy-handler returns 0 or the lock
+** is successfully obtained. ^The busy-handler is also invoked while waiting for
+** database readers as described above. ^If the busy-handler returns 0 before
 ** the writer lock is obtained or while waiting for database readers, the
 ** checkpoint operation proceeds from that point in the same way as 
 ** SQLITE_CHECKPOINT_PASSIVE - checkpointing as many frames as possible 
-** without blocking any further. SQLITE_BUSY is returned in this case.
+** without blocking any further. ^SQLITE_BUSY is returned in this case.
 **
-** If parameter zDb is NULL or points to a zero length string, then the
-** specified operation is attempted on all WAL databases. In this case the
-** values written to output parameters *pnLog and *pnCkpt are undefined. If 
+** ^If parameter zDb is NULL or points to a zero length string, then the
+** specified operation is attempted on all WAL databases [attached] to 
+** [database connection] db.  In this case the
+** values written to output parameters *pnLog and *pnCkpt are undefined. ^If 
 ** an SQLITE_BUSY error is encountered when processing one or more of the 
 ** attached WAL databases, the operation is still attempted on any remaining 
-** attached databases and SQLITE_BUSY is returned to the caller. If any other 
+** attached databases and SQLITE_BUSY is returned at the end. ^If any other 
 ** error occurs while processing an attached database, processing is abandoned 
-** and the error code returned to the caller immediately. If no error 
+** and the error code is returned to the caller immediately. ^If no error 
 ** (SQLITE_BUSY or otherwise) is encountered while processing the attached 
 ** databases, SQLITE_OK is returned.
 **
-** If database zDb is the name of an attached database that is not in WAL
-** mode, SQLITE_OK is returned and both *pnLog and *pnCkpt set to -1. If
+** ^If database zDb is the name of an attached database that is not in WAL
+** mode, SQLITE_OK is returned and both *pnLog and *pnCkpt set to -1. ^If
 ** zDb is not NULL (or a zero length string) and is not the name of any
 ** attached database, SQLITE_ERROR is returned to the caller.
+**
+** ^Unless it returns SQLITE_MISUSE,
+** the sqlite3_wal_checkpoint_v2() interface
+** sets the error information that is queried by
+** [sqlite3_errcode()] and [sqlite3_errmsg()].
+**
+** ^The [PRAGMA wal_checkpoint] command can be used to invoke this interface
+** from SQL.
 */
 int sqlite3_wal_checkpoint_v2(
   sqlite3 *db,                    /* Database handle */
   const char *zDb,                /* Name of attached database (or NULL) */
   int eMode,                      /* SQLITE_CHECKPOINT_* value */
@@ -7345,20 +7367,22 @@
   int *pnLog,                     /* OUT: Size of WAL log in frames */
   int *pnCkpt                     /* OUT: Total number of frames checkpointed */
 );
 
 /*
-** CAPI3REF: Checkpoint operation parameters
+** CAPI3REF: Checkpoint Mode Values
+** KEYWORDS: {checkpoint mode}
 **
-** These constants can be used as the 3rd parameter to
-** [sqlite3_wal_checkpoint_v2()].  See the [sqlite3_wal_checkpoint_v2()]
-** documentation for additional information about the meaning and use of
-** each of these values.
+** These constants define all valid values for the "checkpoint mode" passed
+** as the third parameter to the [sqlite3_wal_checkpoint_v2()] interface.
+** See the [sqlite3_wal_checkpoint_v2()] documentation for details on the
+** meaning of each of these checkpoint modes.
 */
-#define SQLITE_CHECKPOINT_PASSIVE 0
-#define SQLITE_CHECKPOINT_FULL    1
-#define SQLITE_CHECKPOINT_RESTART 2
+#define SQLITE_CHECKPOINT_PASSIVE  0  /* Do as much as possible w/o blocking */
+#define SQLITE_CHECKPOINT_FULL     1  /* Wait for writers, then checkpoint */
+#define SQLITE_CHECKPOINT_RESTART  2  /* Like FULL but wait for for readers */
+#define SQLITE_CHECKPOINT_TRUNCATE 3  /* Like RESTART but also truncate WAL */
 
 /*
 ** CAPI3REF: Virtual Table Interface Configuration
 **
 ** This function may be called by either the [xConnect] or [xCreate] method
@@ -7453,16 +7477,16 @@
 ** [sqlite3_stmt_scanstatus(S,X,T,V)] interface.  Each constant designates a
 ** different metric for sqlite3_stmt_scanstatus() to return.
 **
 ** <dl>
 ** [[SQLITE_SCANSTAT_NLOOP]] <dt>SQLITE_SCANSTAT_NLOOP</dt>
-** <dd>^The [sqlite3_int64] variable pointed to by the T parameter will be set to the
-** total number of times that the X-th loop has run.</dd>
+** <dd>^The [sqlite3_int64] variable pointed to by the T parameter will be
+** set to the total number of times that the X-th loop has run.</dd>
 **
 ** [[SQLITE_SCANSTAT_NVISIT]] <dt>SQLITE_SCANSTAT_NVISIT</dt>
-** <dd>^The [sqlite3_int64] variable pointed to by the T parameter will be set to the
-** total number of rows examined by all iterations of the X-th loop.</dd>
+** <dd>^The [sqlite3_int64] variable pointed to by the T parameter will be set
+** to the total number of rows examined by all iterations of the X-th loop.</dd>
 **
 ** [[SQLITE_SCANSTAT_EST]] <dt>SQLITE_SCANSTAT_EST</dt>
 ** <dd>^The "double" variable pointed to by the T parameter will be set to the
 ** query planner's estimate for the average number of rows output from each
 ** iteration of the X-th loop.  If the query planner's estimates was accurate,
@@ -7469,18 +7493,18 @@
 ** then this value will approximate the quotient NVISIT/NLOOP and the
 ** product of this value for all prior loops with the same SELECTID will
 ** be the NLOOP value for the current loop.
 **
 ** [[SQLITE_SCANSTAT_NAME]] <dt>SQLITE_SCANSTAT_NAME</dt>
-** <dd>^The "const char *" variable pointed to by the T parameter will be set to 
-** a zero-terminated UTF-8 string containing the name of the index or table used
-** for the X-th loop.
+** <dd>^The "const char *" variable pointed to by the T parameter will be set
+** to a zero-terminated UTF-8 string containing the name of the index or table
+** used for the X-th loop.
 **
 ** [[SQLITE_SCANSTAT_EXPLAIN]] <dt>SQLITE_SCANSTAT_EXPLAIN</dt>
-** <dd>^The "const char *" variable pointed to by the T parameter will be set to 
-** a zero-terminated UTF-8 string containing the [EXPLAIN QUERY PLAN] description
-** for the X-th loop.
+** <dd>^The "const char *" variable pointed to by the T parameter will be set
+** to a zero-terminated UTF-8 string containing the [EXPLAIN QUERY PLAN]
+** description for the X-th loop.
 **
 ** [[SQLITE_SCANSTAT_SELECTID]] <dt>SQLITE_SCANSTAT_SELECT</dt>
 ** <dd>^The "int" variable pointed to by the T parameter will be set to the
 ** "select-id" for the X-th loop.  The select-id identifies which query or
 ** subquery the loop is part of.  The main query has a select-id of zero.
@@ -7499,12 +7523,12 @@
 ** CAPI3REF: Prepared Statement Scan Status
 **
 ** Return status data for a single loop within query pStmt.
 **
 ** The "iScanStatusOp" parameter determines which status information to return.
-** The "iScanStatusOp" must be one of the [scanstatus options] or the behavior of
-** this interface is undefined.
+** The "iScanStatusOp" must be one of the [scanstatus options] or the behavior
+** of this interface is undefined.
 ** ^The requested measurement is written into a variable pointed to by
 ** the "pOut" parameter.
 ** Parameter "idx" identifies the specific loop to retrieve statistics for.
 ** Loops are numbered starting from zero. ^If idx is out of range - less than
 ** zero or greater than or equal to the total number of loops used to implement

Index: src/sqliteInt.h
==================================================================
--- src/sqliteInt.h
+++ src/sqliteInt.h
@@ -2018,11 +2018,11 @@
 };
 
 /*
 ** The following are the meanings of bits in the Expr.flags field.
 */
-#define EP_FromJoin  0x000001 /* Originated in ON or USING clause of a join */
+#define EP_FromJoin  0x000001 /* Originates in ON/USING clause of outer join */
 #define EP_Agg       0x000002 /* Contains one or more aggregate functions */
 #define EP_Resolved  0x000004 /* IDs have been resolved to COLUMNs */
 #define EP_Error     0x000008 /* Expression contains one or more errors */
 #define EP_Distinct  0x000010 /* Aggregate function with DISTINCT keyword */
 #define EP_VarSelect 0x000020 /* pSelect is correlated, not constant */
@@ -2038,10 +2038,11 @@
 #define EP_Static    0x008000 /* Held in memory not obtained from malloc() */
 #define EP_MemToken  0x010000 /* Need to sqlite3DbFree() Expr.zToken */
 #define EP_NoReduce  0x020000 /* Cannot EXPRDUP_REDUCE this Expr */
 #define EP_Unlikely  0x040000 /* unlikely() or likelihood() function */
 #define EP_Constant  0x080000 /* Node is a constant */
+#define EP_CanBeNull 0x100000 /* Can be null despite NOT NULL constraint */
 
 /*
 ** These macros can be used to test, set, or clear bits in the 
 ** Expr.flags field.
 */

Index: src/test1.c
==================================================================
--- src/test1.c
+++ src/test1.c
@@ -3636,10 +3636,11 @@
   int objc,
   Tcl_Obj *CONST objv[]
 ){
   sqlite3 *db;
   const char *zSql;
+  char *zCopy = 0;                /* malloc() copy of zSql */
   int bytes;
   const char *zTail = 0;
   sqlite3_stmt *pStmt = 0;
   char zBuf[50];
   int rc;
@@ -3651,11 +3652,25 @@
   }
   if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
   zSql = Tcl_GetString(objv[2]);
   if( Tcl_GetIntFromObj(interp, objv[3], &bytes) ) return TCL_ERROR;
 
-  rc = sqlite3_prepare_v2(db, zSql, bytes, &pStmt, objc>=5 ? &zTail : 0);
+  /* Instead of using zSql directly, make a copy into a buffer obtained
+  ** directly from malloc(). The idea is to make it easier for valgrind
+  ** to spot buffer overreads.  */
+  if( bytes>=0 ){
+    zCopy = malloc(bytes);
+    memcpy(zCopy, zSql, bytes);
+  }else{
+    int n = (int)strlen(zSql) + 1;
+    zCopy = malloc(n);
+    memcpy(zCopy, zSql, n);
+  }
+  rc = sqlite3_prepare_v2(db, zCopy, bytes, &pStmt, objc>=5 ? &zTail : 0);
+  free(zCopy);
+  zTail = &zSql[(zTail - zCopy)];
+
   assert(rc==SQLITE_OK || pStmt==0);
   Tcl_ResetResult(interp);
   if( sqlite3TestErrCode(interp, db, rc) ) return TCL_ERROR;
   if( zTail && objc>=5 ){
     if( bytes>=0 ){
@@ -5673,32 +5688,35 @@
   int eMode;
   int nLog = -555;
   int nCkpt = -555;
   Tcl_Obj *pRet;
 
-  const char * aMode[] = { "passive", "full", "restart", 0 };
+  const char * aMode[] = { "passive", "full", "restart", "truncate", 0 };
   assert( SQLITE_CHECKPOINT_PASSIVE==0 );
   assert( SQLITE_CHECKPOINT_FULL==1 );
   assert( SQLITE_CHECKPOINT_RESTART==2 );
+  assert( SQLITE_CHECKPOINT_TRUNCATE==3 );
 
   if( objc!=3 && objc!=4 ){
     Tcl_WrongNumArgs(interp, 1, objv, "DB MODE ?NAME?");
     return TCL_ERROR;
   }
 
   if( objc==4 ){
     zDb = Tcl_GetString(objv[3]);
   }
-  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db)
-   || Tcl_GetIndexFromObj(interp, objv[2], aMode, "mode", 0, &eMode) 
-  ){
+  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) || (
+      TCL_OK!=Tcl_GetIntFromObj(0, objv[2], &eMode)
+   && TCL_OK!=Tcl_GetIndexFromObj(interp, objv[2], aMode, "mode", 0, &eMode) 
+  )){
     return TCL_ERROR;
   }
 
   rc = sqlite3_wal_checkpoint_v2(db, zDb, eMode, &nLog, &nCkpt);
   if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){
-    Tcl_SetResult(interp, (char *)sqlite3_errmsg(db), TCL_VOLATILE);
+    const char *zErrCode = sqlite3ErrName(rc);
+    Tcl_AppendResult(interp, zErrCode, " - ", (char *)sqlite3_errmsg(db), 0);
     return TCL_ERROR;
   }
 
   pRet = Tcl_NewObj();
   Tcl_ListObjAppendElement(interp, pRet, Tcl_NewIntObj(rc==SQLITE_BUSY?1:0));

Index: src/vdbe.c
==================================================================
--- src/vdbe.c
+++ src/vdbe.c
@@ -5703,12 +5703,12 @@
 
 #ifndef SQLITE_OMIT_WAL
 /* Opcode: Checkpoint P1 P2 P3 * *
 **
 ** Checkpoint database P1. This is a no-op if P1 is not currently in
-** WAL mode. Parameter P2 is one of SQLITE_CHECKPOINT_PASSIVE, FULL
-** or RESTART.  Write 1 or 0 into mem[P3] if the checkpoint returns
+** WAL mode. Parameter P2 is one of SQLITE_CHECKPOINT_PASSIVE, FULL,
+** RESTART, or TRUNCATE.  Write 1 or 0 into mem[P3] if the checkpoint returns
 ** SQLITE_BUSY or not, respectively.  Write the number of pages in the
 ** WAL after the checkpoint into mem[P3+1] and the number of pages
 ** in the WAL that have been checkpointed after the checkpoint
 ** completes into mem[P3+2].  However on an error, mem[P3+1] and
 ** mem[P3+2] are initialized to -1.
@@ -5722,10 +5722,11 @@
   aRes[0] = 0;
   aRes[1] = aRes[2] = -1;
   assert( pOp->p2==SQLITE_CHECKPOINT_PASSIVE
        || pOp->p2==SQLITE_CHECKPOINT_FULL
        || pOp->p2==SQLITE_CHECKPOINT_RESTART
+       || pOp->p2==SQLITE_CHECKPOINT_TRUNCATE
   );
   rc = sqlite3Checkpoint(db, pOp->p1, pOp->p2, &aRes[1], &aRes[2]);
   if( rc==SQLITE_BUSY ){
     rc = SQLITE_OK;
     aRes[0] = 1;

Index: src/vdbeaux.c
==================================================================
--- src/vdbeaux.c
+++ src/vdbeaux.c
@@ -1740,11 +1740,11 @@
     for(n=0; n<nVar; n++){
       p->aVar[n].flags = MEM_Null;
       p->aVar[n].db = db;
     }
   }
-  if( p->azVar ){
+  if( p->azVar && pParse->nzVar>0 ){
     p->nzVar = pParse->nzVar;
     memcpy(p->azVar, pParse->azVar, p->nzVar*sizeof(p->azVar[0]));
     memset(pParse->azVar, 0, pParse->nzVar*sizeof(pParse->azVar[0]));
   }
   if( p->aMem ){

Index: src/vdbesort.c
==================================================================
--- src/vdbesort.c
+++ src/vdbesort.c
@@ -145,10 +145,17 @@
 */
 #if 0
 # define SQLITE_DEBUG_SORTER_THREADS 1
 #endif
 
+/*
+** Hard-coded maximum amount of data to accumulate in memory before flushing
+** to a level 0 PMA. The purpose of this limit is to prevent various integer
+** overflows. 512MiB.
+*/
+#define SQLITE_MAX_MXPMASIZE    (1<<29)
+
 /*
 ** Private objects used by the sorter
 */
 typedef struct MergeEngine MergeEngine;     /* Merge PMAs together */
 typedef struct PmaReader PmaReader;         /* Incrementally read one PMA */
@@ -843,11 +850,11 @@
 
     if( !sqlite3TempInMemory(db) ){
       pSorter->mnPmaSize = SORTER_MIN_WORKING * pgsz;
       mxCache = db->aDb[0].pSchema->cache_size;
       if( mxCache<SORTER_MIN_WORKING ) mxCache = SORTER_MIN_WORKING;
-      pSorter->mxPmaSize = mxCache * pgsz;
+      pSorter->mxPmaSize = MIN((i64)mxCache*pgsz, SQLITE_MAX_MXPMASIZE);
 
       /* EVIDENCE-OF: R-26747-61719 When the application provides any amount of
       ** scratch memory using SQLITE_CONFIG_SCRATCH, SQLite avoids unnecessary
       ** large heap allocations.
       */

Index: src/vtab.c
==================================================================
--- src/vtab.c
+++ src/vtab.c
@@ -330,11 +330,16 @@
   pTable->tabFlags |= TF_Virtual;
   pTable->nModuleArg = 0;
   addModuleArgument(db, pTable, sqlite3NameFromToken(db, pModuleName));
   addModuleArgument(db, pTable, 0);
   addModuleArgument(db, pTable, sqlite3DbStrDup(db, pTable->zName));
-  pParse->sNameToken.n = (int)(&pModuleName->z[pModuleName->n] - pName1->z);
+  assert( (pParse->sNameToken.z==pName2->z && pName2->z!=0)
+       || (pParse->sNameToken.z==pName1->z && pName2->z==0)
+  );
+  pParse->sNameToken.n = (int)(
+      &pModuleName->z[pModuleName->n] - pParse->sNameToken.z
+  );
 
 #ifndef SQLITE_OMIT_AUTHORIZATION
   /* Creating a virtual table invokes the authorization callback twice.
   ** The first invocation, to obtain permission to INSERT a row into the
   ** sqlite_master table, has already been made by sqlite3StartTable().

Index: src/wal.c
==================================================================
--- src/wal.c
+++ src/wal.c
@@ -1826,10 +1826,42 @@
     p->pIter = 0;
   }
 
   return p->rc;
 }
+
+/*
+** The following is guaranteed when this function is called:
+**
+**   a) the WRITER lock is held,
+**   b) the entire log file has been checkpointed, and
+**   c) any existing readers are reading exclusively from the database
+**      file - there are no readers that may attempt to read a frame from
+**      the log file.
+**
+** This function updates the shared-memory structures so that the next
+** client to write to the database (which may be this one) does so by
+** writing frames into the start of the log file.
+**
+** The value of parameter salt1 is used as the aSalt[1] value in the 
+** new wal-index header. It should be passed a pseudo-random value (i.e. 
+** one obtained from sqlite3_randomness()).
+*/
+static void walRestartHdr(Wal *pWal, u32 salt1){
+  volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
+  int i;                          /* Loop counter */
+  u32 *aSalt = pWal->hdr.aSalt;   /* Big-endian salt values */
+  pWal->nCkpt++;
+  pWal->hdr.mxFrame = 0;
+  sqlite3Put4byte((u8*)&aSalt[0], 1 + sqlite3Get4byte((u8*)&aSalt[0]));
+  memcpy(&pWal->hdr.aSalt[1], &salt1, 4);
+  walIndexWriteHdr(pWal);
+  pInfo->nBackfill = 0;
+  pInfo->aReadMark[1] = 0;
+  for(i=2; i<WAL_NREADER; i++) pInfo->aReadMark[i] = READMARK_NOT_USED;
+  assert( pInfo->aReadMark[0]==0 );
+}
 
 /*
 ** Copy as much content as we can from the WAL back into the database file
 ** in response to an sqlite3_wal_checkpoint() request or the equivalent.
 **
@@ -1861,43 +1893,64 @@
 ** time.
 */
 static int walCheckpoint(
   Wal *pWal,                      /* Wal connection */
   int eMode,                      /* One of PASSIVE, FULL or RESTART */
-  int (*xBusyCall)(void*),        /* Function to call when busy */
+  int (*xBusy)(void*),            /* Function to call when busy */
   void *pBusyArg,                 /* Context argument for xBusyHandler */
   int sync_flags,                 /* Flags for OsSync() (or 0) */
   u8 *zBuf,                       /* Temporary buffer to use */
   int nBuf                        /* Size of zBuf in bytes */
 ){
   int rc;                         /* Return code */
-  int (*xBusy)(void*) = 0;        /* Function to call when waiting for locks */
   WalCkpt sC;
 
-  if( eMode!=SQLITE_CHECKPOINT_PASSIVE ) xBusy = xBusyCall;
+  /* EVIDENCE-OF: R-62920-47450 The busy-handler callback is never invoked
+  ** in the SQLITE_CHECKPOINT_PASSIVE mode. */
+  assert( eMode!=SQLITE_CHECKPOINT_PASSIVE || xBusy==0 );
+
   rc = walCheckpointStart(pWal, zBuf, nBuf, xBusy, pBusyArg, sync_flags, &sC);
   if( sC.pIter==0 ) goto walcheckpoint_out;
   assert( rc==SQLITE_OK );
 
   /* Step the checkpoint object until it reports something other than 
   ** SQLITE_OK.  */
   while( SQLITE_OK==(rc = walCheckpointStep(&sC)) );
   rc = walCheckpointFinalize(&sC);
 
-  /* If this is an SQLITE_CHECKPOINT_RESTART operation, and the entire wal
-  ** file has been copied into the database file, then block until all
-  ** readers have finished using the wal file. This ensures that the next
-  ** process to write to the database restarts the wal file.
+  /* If this is an SQLITE_CHECKPOINT_RESTART or TRUNCATE operation, and the
+  ** entire wal file has been copied into the database file, then block 
+  ** until all readers have finished using the wal file. This ensures that 
+  ** the next process to write to the database restarts the wal file.
   */
   if( rc==SQLITE_OK && eMode!=SQLITE_CHECKPOINT_PASSIVE ){
     assert( pWal->writeLock );
     if( sC.pInfo->nBackfill<pWal->hdr.mxFrame ){
       rc = SQLITE_BUSY;
-    }else if( eMode==SQLITE_CHECKPOINT_RESTART ){
+    }else if( eMode>=SQLITE_CHECKPOINT_RESTART ){
+      u32 salt1;
+      sqlite3_randomness(4, &salt1);
       assert( sC.mxSafeFrame==pWal->hdr.mxFrame );
       rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(1), WAL_NREADER-1);
       if( rc==SQLITE_OK ){
+        if( eMode==SQLITE_CHECKPOINT_TRUNCATE ){
+          /* IMPLEMENTATION-OF: R-44699-57140 This mode works the same way as
+          ** SQLITE_CHECKPOINT_RESTART with the addition that it also
+          ** truncates the log file to zero bytes just prior to a
+          ** successful return.
+          **
+          ** In theory, it might be safe to do this without updating the
+          ** wal-index header in shared memory, as all subsequent reader or
+          ** writer clients should see that the entire log file has been
+          ** checkpointed and behave accordingly. This seems unsafe though,
+          ** as it would leave the system in a state where the contents of
+          ** the wal-index header do not match the contents of the 
+          ** file-system. To avoid this, update the wal-index header to
+          ** indicate that the log file contains zero valid frames.  */
+          walRestartHdr(pWal, salt1);
+          rc = sqlite3OsTruncate(pWal->pWalFd, 0);
+        }
         walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
       }
     }
   }
 
@@ -2687,11 +2740,10 @@
   }
 
   return rc;
 }
 
-
 /*
 ** This function is called just before writing a set of frames to the log
 ** file (see sqlite3WalFrames()). It checks to see if, instead of appending
 ** to the current log file, it is possible to overwrite the start of the
 ** existing log file with the new frames (i.e. "reset" the log). If so,
@@ -2720,24 +2772,12 @@
         ** wal-index header to reflect this.
         **
         ** In theory it would be Ok to update the cache of the header only
         ** at this point. But updating the actual wal-index header is also
         ** safe and means there is no special case for sqlite3WalUndo()
-        ** to handle if this transaction is rolled back.
-        */
-        int i;                    /* Loop counter */
-        u32 *aSalt = pWal->hdr.aSalt;       /* Big-endian salt values */
-
-        pWal->nCkpt++;
-        pWal->hdr.mxFrame = 0;
-        sqlite3Put4byte((u8*)&aSalt[0], 1 + sqlite3Get4byte((u8*)&aSalt[0]));
-        aSalt[1] = salt1;
-        walIndexWriteHdr(pWal);
-        pInfo->nBackfill = 0;
-        pInfo->aReadMark[1] = 0;
-        for(i=2; i<WAL_NREADER; i++) pInfo->aReadMark[i] = READMARK_NOT_USED;
-        assert( pInfo->aReadMark[0]==0 );
+        ** to handle if this transaction is rolled back.  */
+        walRestartHdr(pWal, salt1);
         walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
       }else if( rc!=SQLITE_BUSY ){
         return rc;
       }
     }
@@ -3023,11 +3063,11 @@
 ** If parameter xBusy is not NULL, it is a pointer to a busy-handler
 ** callback. In this case this function runs a blocking checkpoint.
 */
 int sqlite3WalCheckpoint(
   Wal *pWal,                      /* Wal connection */
-  int eMode,                      /* PASSIVE, FULL or RESTART */
+  int eMode,                      /* PASSIVE, FULL, RESTART, or TRUNCATE */
   int (*xBusy)(void*),            /* Function to call when busy */
   void *pBusyArg,                 /* Context argument for xBusyHandler */
   int sync_flags,                 /* Flags to sync db file with (or 0) */
   int nBuf,                       /* Size of temporary buffer */
   u8 *zBuf,                       /* Temporary buffer to use */
@@ -3035,40 +3075,54 @@
   int *pnCkpt                     /* OUT: Number of backfilled frames in WAL */
 ){
   int rc;                         /* Return code */
   int isChanged = 0;              /* True if a new wal-index header is loaded */
   int eMode2 = eMode;             /* Mode to pass to walCheckpoint() */
+  int (*xBusy2)(void*) = xBusy;   /* Busy handler for eMode2 */
 
   assert( pWal->ckptLock==0 );
   assert( pWal->writeLock==0 );
 
+  /* EVIDENCE-OF: R-62920-47450 The busy-handler callback is never invoked
+  ** in the SQLITE_CHECKPOINT_PASSIVE mode. */
+  assert( eMode!=SQLITE_CHECKPOINT_PASSIVE || xBusy==0 );
+
   if( pWal->readOnly ) return SQLITE_READONLY;
   WALTRACE(("WAL%p: checkpoint begins\n", pWal));
+
+  /* IMPLEMENTATION-OF: R-62028-47212 All calls obtain an exclusive 
+  ** "checkpoint" lock on the database file. */
   rc = walLockExclusive(pWal, WAL_CKPT_LOCK, 1);
   if( rc ){
-    /* Usually this is SQLITE_BUSY meaning that another thread or process
-    ** is already running a checkpoint, or maybe a recovery.  But it might
-    ** also be SQLITE_IOERR. */
+    /* EVIDENCE-OF: R-10421-19736 If any other process is running a
+    ** checkpoint operation at the same time, the lock cannot be obtained and
+    ** SQLITE_BUSY is returned.
+    ** EVIDENCE-OF: R-53820-33897 Even if there is a busy-handler configured,
+    ** it will not be invoked in this case.
+    */
+    testcase( rc==SQLITE_BUSY );
+    testcase( xBusy!=0 );
     return rc;
   }
   pWal->ckptLock = 1;
 
-  /* If this is a blocking-checkpoint, then obtain the write-lock as well
-  ** to prevent any writers from running while the checkpoint is underway.
-  ** This has to be done before the call to walIndexReadHdr() below.
+  /* IMPLEMENTATION-OF: R-59782-36818 The SQLITE_CHECKPOINT_FULL, RESTART and
+  ** TRUNCATE modes also obtain the exclusive "writer" lock on the database
+  ** file.
   **
-  ** If the writer lock cannot be obtained, then a passive checkpoint is
-  ** run instead. Since the checkpointer is not holding the writer lock,
-  ** there is no point in blocking waiting for any readers. Assuming no 
-  ** other error occurs, this function will return SQLITE_BUSY to the caller.
+  ** EVIDENCE-OF: R-60642-04082 If the writer lock cannot be obtained
+  ** immediately, and a busy-handler is configured, it is invoked and the
+  ** writer lock retried until either the busy-handler returns 0 or the
+  ** lock is successfully obtained.
   */
   if( eMode!=SQLITE_CHECKPOINT_PASSIVE ){
     rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_WRITE_LOCK, 1);
     if( rc==SQLITE_OK ){
       pWal->writeLock = 1;
     }else if( rc==SQLITE_BUSY ){
       eMode2 = SQLITE_CHECKPOINT_PASSIVE;
+      xBusy2 = 0;
       rc = SQLITE_OK;
     }
   }
 
   /* Read the wal-index header. */
@@ -3079,11 +3133,11 @@
     }
   }
 
   /* Copy data from the log to the database file. */
   if( rc==SQLITE_OK ){
-    rc = walCheckpoint(pWal, eMode2, xBusy, pBusyArg, sync_flags, zBuf, nBuf);
+    rc = walCheckpoint(pWal, eMode2, xBusy2, pBusyArg, sync_flags, zBuf, nBuf);
 
     /* If no error occurred, set the output variables. */
     if( rc==SQLITE_OK || rc==SQLITE_BUSY ){
       if( pnLog ) *pnLog = (int)pWal->hdr.mxFrame;
       if( pnCkpt ) *pnCkpt = (int)(walCkptInfo(pWal)->nBackfill);

Index: src/where.c
==================================================================
--- src/where.c
+++ src/where.c
@@ -220,10 +220,11 @@
     memcpy(pWC->a, pOld, sizeof(pWC->a[0])*pWC->nTerm);
     if( pOld!=pWC->aStatic ){
       sqlite3DbFree(db, pOld);
     }
     pWC->nSlot = sqlite3DbMallocSize(db, pWC->a)/sizeof(pWC->a[0]);
+    memset(&pWC->a[pWC->nTerm], 0, sizeof(pWC->a[0])*(pWC->nSlot-pWC->nTerm));
   }
   pTerm = &pWC->a[idx = pWC->nTerm++];
   if( p && ExprHasProperty(p, EP_Unlikely) ){
     pTerm->truthProb = sqlite3LogEst(p->iTable) - 270;
   }else{
@@ -2945,11 +2946,11 @@
   WhereLevel *pLvl,               /* Level to add scanstatus() entry for */
   int addrExplain                 /* Address of OP_Explain (or 0) */
 ){
   const char *zObj = 0;
   WhereLoop *pLoop = pLvl->pWLoop;
-  if( (pLoop->wsFlags & (WHERE_IPK|WHERE_VIRTUALTABLE))==0 ){
+  if( (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0  &&  pLoop->u.btree.pIndex!=0 ){
     zObj = pLoop->u.btree.pIndex->zName;
   }else{
     zObj = pSrclist->a[pLvl->iFrom].zName;
   }
   sqlite3VdbeScanStatus(
@@ -3589,14 +3590,13 @@
       int iTerm;
       for(iTerm=0; iTerm<pWC->nTerm; iTerm++){
         Expr *pExpr = pWC->a[iTerm].pExpr;
         if( &pWC->a[iTerm] == pTerm ) continue;
         if( ExprHasProperty(pExpr, EP_FromJoin) ) continue;
-        testcase( pWC->a[iTerm].wtFlags & TERM_ORINFO );
-        testcase( pWC->a[iTerm].wtFlags & TERM_VIRTUAL );
-        if( pWC->a[iTerm].wtFlags & (TERM_ORINFO|TERM_VIRTUAL) ) continue;
+        if( (pWC->a[iTerm].wtFlags & TERM_VIRTUAL)!=0 ) continue;
         if( (pWC->a[iTerm].eOperator & WO_ALL)==0 ) continue;
+        testcase( pWC->a[iTerm].wtFlags & TERM_ORINFO );
         pExpr = sqlite3ExprDup(db, pExpr, 0);
         pAndExpr = sqlite3ExprAnd(db, pAndExpr, pExpr);
       }
       if( pAndExpr ){
         pAndExpr = sqlite3PExpr(pParse, TK_AND, 0, pAndExpr, 0);
@@ -4289,25 +4289,46 @@
 
 /*
 ** Adjust the WhereLoop.nOut value downward to account for terms of the
 ** WHERE clause that reference the loop but which are not used by an
 ** index.
+*
+** For every WHERE clause term that is not used by the index
+** and which has a truth probability assigned by one of the likelihood(),
+** likely(), or unlikely() SQL functions, reduce the estimated number
+** of output rows by the probability specified.
+**
+** TUNING:  For every WHERE clause term that is not used by the index
+** and which does not have an assigned truth probability, heuristics
+** described below are used to try to estimate the truth probability.
+** TODO --> Perhaps this is something that could be improved by better
+** table statistics.
+**
+** Heuristic 1:  Estimate the truth probability as 93.75%.  The 93.75%
+** value corresponds to -1 in LogEst notation, so this means decrement
+** the WhereLoop.nOut field for every such WHERE clause term.
 **
-** In the current implementation, the first extra WHERE clause term reduces
-** the number of output rows by a factor of 10 and each additional term
-** reduces the number of output rows by sqrt(2).
+** Heuristic 2:  If there exists one or more WHERE clause terms of the
+** form "x==EXPR" and EXPR is not a constant 0 or 1, then make sure the
+** final output row estimate is no greater than 1/4 of the total number
+** of rows in the table.  In other words, assume that x==EXPR will filter
+** out at least 3 out of 4 rows.  If EXPR is -1 or 0 or 1, then maybe the
+** "x" column is boolean or else -1 or 0 or 1 is a common default value
+** on the "x" column and so in that case only cap the output row estimate
+** at 1/2 instead of 1/4.
 */
 static void whereLoopOutputAdjust(
   WhereClause *pWC,      /* The WHERE clause */
   WhereLoop *pLoop,      /* The loop to adjust downward */
   LogEst nRow            /* Number of rows in the entire table */
 ){
   WhereTerm *pTerm, *pX;
   Bitmask notAllowed = ~(pLoop->prereq|pLoop->maskSelf);
-  int i, j;
-  int nEq = 0;    /* Number of = constraints not within likely()/unlikely() */
+  int i, j, k;
+  LogEst iReduce = 0;    /* pLoop->nOut should not exceed nRow-iReduce */
 
+  assert( (pLoop->wsFlags & WHERE_AUTO_INDEX)==0 );
   for(i=pWC->nTerm, pTerm=pWC->a; i>0; i--, pTerm++){
     if( (pTerm->wtFlags & TERM_VIRTUAL)!=0 ) break;
     if( (pTerm->prereqAll & pLoop->maskSelf)==0 ) continue;
     if( (pTerm->prereqAll & notAllowed)!=0 ) continue;
     for(j=pLoop->nLTerm-1; j>=0; j--){
@@ -4316,24 +4337,30 @@
       if( pX==pTerm ) break;
       if( pX->iParent>=0 && (&pWC->a[pX->iParent])==pTerm ) break;
     }
     if( j<0 ){
       if( pTerm->truthProb<=0 ){
+        /* If a truth probability is specified using the likelihood() hints,
+        ** then use the probability provided by the application. */
         pLoop->nOut += pTerm->truthProb;
       }else{
+        /* In the absence of explicit truth probabilities, use heuristics to
+        ** guess a reasonable truth probability. */
         pLoop->nOut--;
-        if( pTerm->eOperator&WO_EQ ) nEq++;
+        if( pTerm->eOperator&WO_EQ ){
+          Expr *pRight = pTerm->pExpr->pRight;
+          if( sqlite3ExprIsInteger(pRight, &k) && k>=(-1) && k<=1 ){
+            k = 10;
+          }else{
+            k = 20;
+          }
+          if( iReduce<k ) iReduce = k;
+        }
       }
     }
   }
-  /* TUNING:  If there is at least one equality constraint in the WHERE
-  ** clause that does not have a likelihood() explicitly assigned to it
-  ** then do not let the estimated number of output rows exceed half 
-  ** the number of rows in the table. */
-  if( nEq && pLoop->nOut>nRow-10 ){
-    pLoop->nOut = nRow - 10;
-  }
+  if( pLoop->nOut > nRow-iReduce )  pLoop->nOut = nRow - iReduce;
 }
 
 /*
 ** Adjust the cost C by the costMult facter T.  This only occurs if
 ** compiled with -DSQLITE_ENABLE_COSTMULT

Index: test/autoindex2.test
==================================================================
--- test/autoindex2.test
+++ test/autoindex2.test
@@ -222,50 +222,6 @@
 #
 # ^^^--- Before being fixed, the above was using an automatic covering
 # on t3 and reordering the tables so that t3 was in the outer loop and
 # implementing the ORDER BY clause using a B-Tree.
 
-do_execsql_test autoindex2-120 {
-  EXPLAIN QUERY PLAN
-  SELECT
-     t1_id,
-     t1.did,
-     param2,
-     param3,
-     t1.ptime,
-     t1.trange,
-     t1.exmass,
-     t1.mass,
-     t1.vstatus,
-     type,
-     subtype,
-     t1.deviation,
-     t1.formula,
-     dparam1,
-     reserve1,
-     reserve2,
-     param4,
-     t1.last_operation,
-     t1.admin_uuid,
-     t1.previous_value,
-     t1.job_id,
-     client_did, 
-     t1.last_t1,
-     t1.data_t1,
-     t1.previous_date,
-     param5,
-     param6,
-     mgr_uuid
-  FROM
-     t3,
-     t2,
-     t1
-  WHERE
-     t1.ptime > 1393520400
-     AND param3<>9001
-     AND t3.flg7 = 1
-     AND t1.did = t2.did
-     AND t2.uid = t3.uid
-  ORDER BY t1.ptime desc LIMIT 500;
-} {0 0 2 {SEARCH TABLE t1 USING INDEX t1x1 (ptime>?)} 0 1 1 {SEARCH TABLE t2 USING INDEX t2x0 (did=?)} 0 2 0 {SEARCH TABLE t3 USING INDEX t3x0 (uid=?)}}
-
 finish_test

ADDED   test/bigsort.test
Index: test/bigsort.test
==================================================================
--- /dev/null
+++ test/bigsort.test
@@ -0,0 +1,43 @@
+# 2014 November 26
+#
+# 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.
+#
+#***********************************************************************
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+set testprefix bigsort
+
+#--------------------------------------------------------------------
+# At one point there was an overflow problem if the product of the 
+# cache-size and page-size was larger than 2^31. Causing an infinite 
+# loop if the product was also an integer multiple of 2^32, or 
+# inefficiency otherwise.
+#
+do_execsql_test 1.0 {
+  PRAGMA page_size = 1024;
+  CREATE TABLE t1(a, b);
+  BEGIN;
+  WITH data(x,y) AS (
+    SELECT 1, zeroblob(10000)
+    UNION ALL
+    SELECT x+1, y FROM data WHERE x < 300000
+  )
+  INSERT INTO t1 SELECT * FROM data;
+  COMMIT;
+}
+do_execsql_test 1.1 {
+  PRAGMA cache_size = 4194304;
+  CREATE INDEX i1 ON t1(a, b);
+}
+
+
+finish_test
+
+

ADDED   test/btree01.test
Index: test/btree01.test
==================================================================
--- /dev/null
+++ test/btree01.test
@@ -0,0 +1,132 @@
+# 2014-11-27
+#
+# 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 file contains test cases for b-tree logic.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+set testprefix btree01
+
+# The refactoring on the b-tree balance() routine in check-in
+# http://www.sqlite.org/src/info/face33bea1ba3a (2014-10-27)
+# caused the integrity_check on the following SQL to fail.
+#
+do_execsql_test btree01-1.1 {
+  PRAGMA page_size=65536;
+  CREATE TABLE t1(a INTEGER PRIMARY KEY, b BLOB);
+  WITH RECURSIVE
+     c(i) AS (VALUES(1) UNION ALL SELECT i+1 FROM c WHERE i<30)
+  INSERT INTO t1(a,b) SELECT i, zeroblob(6500) FROM c;
+  UPDATE t1 SET b=zeroblob(3000);
+  UPDATE t1 SET b=zeroblob(64000) WHERE a=2;
+  PRAGMA integrity_check;
+} {ok}
+
+# The previous test is sufficient to prevent a regression.  But we
+# add a number of additional tests to stress the balancer in similar
+# ways, looking for related problems.
+#
+for {set i 1} {$i<=30} {incr i} {
+  do_test btree01-1.2.$i {
+    db eval {
+      DELETE FROM t1;
+      WITH RECURSIVE
+        c(i) AS (VALUES(1) UNION ALL SELECT i+1 FROM c WHERE i<30)
+      INSERT INTO t1(a,b) SELECT i, zeroblob(6500) FROM c;
+      UPDATE t1 SET b=zeroblob(3000);
+      UPDATE t1 SET b=zeroblob(64000) WHERE a=$::i;
+      PRAGMA integrity_check;
+    }
+  } {ok}
+}
+for {set i 1} {$i<=30} {incr i} {
+  do_test btree01-1.3.$i {
+    db eval {
+      DELETE FROM t1;
+      WITH RECURSIVE
+        c(i) AS (VALUES(1) UNION ALL SELECT i+1 FROM c WHERE i<30)
+      INSERT INTO t1(a,b) SELECT i, zeroblob(6500) FROM c;
+      UPDATE t1 SET b=zeroblob(2000);
+      UPDATE t1 SET b=zeroblob(64000) WHERE a=$::i;
+      PRAGMA integrity_check;
+    }
+  } {ok}
+}
+for {set i 1} {$i<=30} {incr i} {
+  do_test btree01-1.4.$i {
+    db eval {
+      DELETE FROM t1;
+      WITH RECURSIVE
+        c(i) AS (VALUES(1) UNION ALL SELECT i+1 FROM c WHERE i<30)
+      INSERT INTO t1(a,b) SELECT i, zeroblob(6500) FROM c;
+      UPDATE t1 SET b=zeroblob(6499) WHERE (a%3)==0;
+      UPDATE t1 SET b=zeroblob(6499) WHERE (a%3)==1;
+      UPDATE t1 SET b=zeroblob(6499) WHERE (a%3)==2;
+      UPDATE t1 SET b=zeroblob(64000) WHERE a=$::i;
+      PRAGMA integrity_check;
+    }
+  } {ok}
+}
+for {set i 1} {$i<=30} {incr i} {
+  do_test btree01-1.5.$i {
+    db eval {
+      DELETE FROM t1;
+      WITH RECURSIVE
+        c(i) AS (VALUES(1) UNION ALL SELECT i+1 FROM c WHERE i<30)
+      INSERT INTO t1(a,b) SELECT i, zeroblob(6542) FROM c;
+      UPDATE t1 SET b=zeroblob(2331);
+      UPDATE t1 SET b=zeroblob(65496) WHERE a=$::i;
+      PRAGMA integrity_check;
+    }
+  } {ok}
+}
+for {set i 1} {$i<=30} {incr i} {
+  do_test btree01-1.6.$i {
+    db eval {
+      DELETE FROM t1;
+      WITH RECURSIVE
+        c(i) AS (VALUES(1) UNION ALL SELECT i+1 FROM c WHERE i<30)
+      INSERT INTO t1(a,b) SELECT i, zeroblob(6542) FROM c;
+      UPDATE t1 SET b=zeroblob(2332);
+      UPDATE t1 SET b=zeroblob(65496) WHERE a=$::i;
+      PRAGMA integrity_check;
+    }
+  } {ok}
+}
+for {set i 1} {$i<=30} {incr i} {
+  do_test btree01-1.7.$i {
+    db eval {
+      DELETE FROM t1;
+      WITH RECURSIVE
+        c(i) AS (VALUES(1) UNION ALL SELECT i+1 FROM c WHERE i<30)
+      INSERT INTO t1(a,b) SELECT i, zeroblob(6500) FROM c;
+      UPDATE t1 SET b=zeroblob(1);
+      UPDATE t1 SET b=zeroblob(65000) WHERE a=$::i;
+      PRAGMA integrity_check;
+    }
+  } {ok}
+}
+for {set i 1} {$i<=31} {incr i} {
+  do_test btree01-1.8.$i {
+    db eval {
+      DELETE FROM t1;
+      WITH RECURSIVE
+        c(i) AS (VALUES(1) UNION ALL SELECT i+1 FROM c WHERE i<31)
+      INSERT INTO t1(a,b) SELECT i, zeroblob(6500) FROM c;
+      UPDATE t1 SET b=zeroblob(4000);
+      UPDATE t1 SET b=zeroblob(65000) WHERE a=$::i;
+      PRAGMA integrity_check;
+    }
+  } {ok}
+}
+
+finish_test

Index: test/distinct.test
==================================================================
--- test/distinct.test
+++ test/distinct.test
@@ -219,7 +219,37 @@
              WHEN 2 THEN zeroblob(5)
              ELSE 'xyzzy' END
       FROM t1;
   SELECT quote(x) FROM t2 ORDER BY 1;
 } {'xyzzy' X'0000000000'}
+
+#----------------------------------------------------------------------------
+# Ticket [c5ea805691bfc4204b1cb9e9aa0103bd48bc7d34] (2014-12-04)
+# Make sure that DISTINCT works together with ORDER BY and descending
+# indexes.
+#
+do_execsql_test 5.1 {
+  DROP TABLE IF EXISTS t1;
+  CREATE TABLE t1(x);
+  INSERT INTO t1(x) VALUES(3),(1),(5),(2),(6),(4),(5),(1),(3);
+  CREATE INDEX t1x ON t1(x DESC);
+  SELECT DISTINCT x FROM t1 ORDER BY x ASC;
+} {1 2 3 4 5 6}
+do_execsql_test 5.2 {
+  SELECT DISTINCT x FROM t1 ORDER BY x DESC;
+} {6 5 4 3 2 1}
+do_execsql_test 5.3 {
+  SELECT DISTINCT x FROM t1 ORDER BY x;
+} {1 2 3 4 5 6}
+do_execsql_test 5.4 {
+  DROP INDEX t1x;
+  CREATE INDEX t1x ON t1(x ASC);
+  SELECT DISTINCT x FROM t1 ORDER BY x ASC;
+} {1 2 3 4 5 6}
+do_execsql_test 5.5 {
+  SELECT DISTINCT x FROM t1 ORDER BY x DESC;
+} {6 5 4 3 2 1}
+do_execsql_test 5.6 {
+  SELECT DISTINCT x FROM t1 ORDER BY x;
+} {1 2 3 4 5 6}
 
 finish_test

ADDED   test/e_walckpt.test
Index: test/e_walckpt.test
==================================================================
--- /dev/null
+++ test/e_walckpt.test
@@ -0,0 +1,290 @@
+# 2014 December 04
+#
+# 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.
+#
+#***********************************************************************
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+source $testdir/wal_common.tcl
+set testprefix e_walckpt
+
+# The following two commands are used to determine if any of the files
+# "test.db", "test.db2" and "test.db3" are modified by a test case.
+#
+# The [save_db_hashes] command saves a hash of the current contents of
+# all three files in global variables. The [compare_db_hashes] compares
+# the current contents with the saved hashes and returns a list of the
+# files that have changed.
+#
+proc save_db_hashes {} {
+  global H
+  foreach f {test.db test.db2 test.db3} {
+    set H($f) 0
+    catch { set H($f) [md5file $f] }
+  }
+}
+proc compare_db_hashes {} {
+  global H
+  set ret [list]
+  foreach f {test.db test.db2 test.db3} {
+    set expect 0
+    catch { set expect [md5file $f] }
+    if {$H($f) != $expect} { lappend ret $f }
+  }
+  set ret
+}
+
+
+# The following tests are run 3 times, each using a different method of 
+# invoking a checkpoint:
+#
+#   1) Using sqlite3_wal_checkpoint_v2()
+#   2) Using "PRAGMA wal_checkpoint"
+#   3) Using sqlite3_wal_checkpoint() in place of checkpoint_v2(PASSIVE)
+#
+# Cases (2) and (3) are to show that the following statements are 
+# correct, respectively:
+#
+# EVIDENCE-OF: R-36706-10507 The PRAGMA wal_checkpoint command can be
+# used to invoke this interface from SQL.
+#
+# EVIDENCE-OF: R-41613-20553 The sqlite3_wal_checkpoint(D,X) is
+# equivalent to
+# sqlite3_wal_checkpoint_v2(D,X,SQLITE_CHECKPOINT_PASSIVE,0,0).
+# 
+foreach {tn script} {
+  1 {
+    proc checkpoint {db mode args} {
+      eval sqlite3_wal_checkpoint_v2 [list $db] [list $mode] $args
+    }
+  }
+
+  2 {
+    proc checkpoint {db mode args} {
+      set sql "PRAGMA wal_checkpoint"
+      if {[llength $args] && [lindex $args 0]!=""} {
+        set sql "PRAGMA [lindex $args 0].wal_checkpoint"
+      }
+      set rc [catch { $db eval $sql } msg]
+      if {$rc} {
+        regsub {database} $msg {database:} msg
+        error "[sqlite3_errcode $db] - $msg"
+      }
+      set msg
+    }
+  }
+
+  3 {
+    proc checkpoint {db mode args} {
+      if {$mode == "passive"} {
+        set rc [eval sqlite3_wal_checkpoint [list $db] $args]
+        if {$rc != "SQLITE_OK"} {
+          error "$rc - [sqlite3_errmsg $db]"
+        }
+      } else {
+        eval sqlite3_wal_checkpoint_v2 [list $db] [list $mode] $args
+      }
+    }
+  }
+
+} {
+
+  eval $script
+
+  reset_db
+  forcedelete test.db2 test.db3 test.db4
+  execsql {
+    ATTACH 'test.db2' AS aux;
+    ATTACH 'test.db3' AS aux2;
+    ATTACH 'test.db4' AS aux3;
+    CREATE TABLE t1(x);
+    CREATE TABLE aux.t2(x);
+    CREATE TABLE aux2.t3(x);
+    CREATE TABLE aux3.t4(x);
+    PRAGMA main.journal_mode = WAL;
+    PRAGMA aux.journal_mode = WAL;
+    PRAGMA aux2.journal_mode = WAL;
+    /* Leave aux4 in rollback mode */
+  }
+
+  # EVIDENCE-OF: R-49787-09095 The sqlite3_wal_checkpoint_v2(D,X,M,L,C)
+  # interface runs a checkpoint operation on database X of database
+  # connection D in mode M. Status information is written back into
+  # integers pointed to by L and C.
+  #
+  #     Tests 1, 2 and 3 below verify the "on database X" part of the
+  #     above. Other parts of this requirement are tested below.
+  #
+  # EVIDENCE-OF: R-00653-06026 If parameter zDb is NULL or points to a
+  # zero length string, then the specified operation is attempted on all
+  # WAL databases attached to database connection db.
+  #
+  #     Tests 4 and 5 below test this.
+  #
+  foreach {tn2 zDb dblist} {
+    1 main  test.db
+    2 aux   test.db2
+    3 aux2  test.db3
+    4 ""    {test.db test.db2 test.db3}
+    5 -     {test.db test.db2 test.db3}
+    6 temp  {}
+  } {
+    do_test $tn.1.$tn2 {
+      execsql {
+        INSERT INTO t1 VALUES(1);
+        INSERT INTO t2 VALUES(2);
+        INSERT INTO t3 VALUES(3);
+      }
+      save_db_hashes
+
+      if {$zDb == "-"} {
+        checkpoint db passive
+      } else {
+        checkpoint db passive $zDb
+      }
+
+      compare_db_hashes
+    } $dblist
+  }
+
+  # EVIDENCE-OF: R-38207-48996 If zDb is not NULL (or a zero length
+  # string) and is not the name of any attached database, SQLITE_ERROR is
+  # returned to the caller.
+  do_test $tn.2.1 {
+    list [catch { checkpoint db passive notadb } msg] $msg
+  } {1 {SQLITE_ERROR - unknown database: notadb}}
+
+  # EVIDENCE-OF: R-14303-42483 If database zDb is the name of an attached
+  # database that is not in WAL mode, SQLITE_OK is returned and both
+  # *pnLog and *pnCkpt set to -1.
+  #
+  if {$tn==3} {
+    # With sqlite3_wal_checkpoint() the two output variables cannot be 
+    # tested. So just test that no error is returned when attempting to
+    # checkpoint a db in rollback mode.
+    do_test $tn.2.2.a { checkpoint db passive aux3 } {}
+  } else {
+    do_test $tn.2.2.b { checkpoint db passive aux3 } {0 -1 -1}
+  }
+
+  # EVIDENCE-OF: R-62028-47212 All calls obtain an exclusive "checkpoint"
+  # lock on the database file.
+  db close
+  testvfs tvfs
+  tvfs filter xShmLock
+  tvfs script filelock
+  proc filelock {method file handle details} {
+    # Test for an exclusive checkpoint lock. A checkpoint lock locks a
+    # single byte starting at offset 1.
+    if {$details == "1 1 lock exclusive"} { set ::seen_checkpoint_lock 1 }
+  }
+  sqlite3 db test.db -vfs tvfs
+  do_test $tn.3.1 {
+    execsql { INSERT INTO t1 VALUES('xyz') }
+    unset -nocomplain ::seen_checkpoint_lock
+    checkpoint db passive
+    set ::seen_checkpoint_lock
+  } {1}
+  db close
+  tvfs delete
+  reset_db
+
+
+ 
+
+  #-----------------------------------------------------------------------
+  # EVIDENCE-OF: R-10421-19736 If any other process is running a
+  # checkpoint operation at the same time, the lock cannot be obtained and
+  # SQLITE_BUSY is returned.
+  #
+  # EVIDENCE-OF: R-53820-33897 Even if there is a busy-handler configured,
+  # it will not be invoked in this case.
+  #
+  testvfs tvfs
+  tvfs filter xWrite
+  sqlite3 db test.db -vfs tvfs
+  sqlite3 db2 test.db -vfs tvfs
+
+  do_test $tn.3.2.1 {
+    db2 eval {
+      PRAGMA journal_mode = WAL;
+      CREATE TABLE t1(x, y);
+      INSERT INTO t1 VALUES(1,2);
+      INSERT INTO t1 VALUES(3,4);
+      INSERT INTO t1 VALUES(5,6);
+    }
+    file size test.db-wal
+  } [wal_file_size 5 1024]
+
+
+  # Connection [db] runs a checkpoint. During this checkpoint, each
+  # time it calls xWrite() to write a page into the database file, we
+  # attempt to start a checkpoint using [db2]. According to the 
+  # first requirement being tested, this should return SQLITE_BUSY. According
+  # to the second, the busy-handler belonging to [db2] should not be
+  # invoked.
+  #
+  set ::write_count 0
+  set ::write_errors [list]
+  proc busy_callback {args} {
+    lappend ::write_errors "busy handler called!"
+  }
+  proc write_callback {args} {
+    set rc [catch {checkpoint db2 passive} msg]
+    if {0==[regexp "database is locked" $msg] && $msg!="1 -1 -1"} {
+      lappend ::write_errors "$rc $msg"
+    } 
+    incr ::write_count
+  }
+  db2 busy busy_callback
+  tvfs script write_callback
+
+  do_test $tn.3.2.2 {
+    db eval {SELECT * FROM sqlite_master}
+    checkpoint db full
+    set ::write_count
+  } {2}
+
+  do_test $tn.3.2.3 {
+    set ::write_errors
+  } {}
+
+  db close
+  db2 close
+  tvfs delete
+
+}
+
+#-----------------------------------------------------------------------
+# EVIDENCE-OF: R-03996-12088 The M parameter must be a valid checkpoint
+# mode:
+#
+#   Valid checkpoint modes are 0, 1, 2 and 3.
+#
+sqlite3 db test.db
+foreach {tn mode res} {
+  0 -1001    {1 {SQLITE_MISUSE - not an error}}
+  1 -1       {1 {SQLITE_MISUSE - not an error}}
+  2  0       {0 {0 -1 -1}}
+  3  1       {0 {0 -1 -1}}
+  4  2       {0 {0 -1 -1}}
+  5  3       {0 {0 -1 -1}}
+  6  4       {1 {SQLITE_MISUSE - not an error}}
+  7  114     {1 {SQLITE_MISUSE - not an error}}
+  8  1000000 {1 {SQLITE_MISUSE - not an error}}
+} {
+  do_test 4.$tn {
+    list [catch "sqlite3_wal_checkpoint_v2 db $mode" msg] $msg
+  } $res
+}
+
+
+finish_test

Index: test/join5.test
==================================================================
--- test/join5.test
+++ test/join5.test
@@ -104,7 +104,61 @@
 } {}
 do_test join5-2.12 {
   execsql {SELECT * FROM xy LEFT JOIN ab ON NULL WHERE NULL}
 } {}
 
+# Ticket https://www.sqlite.org/src/tktview/6f2222d550f5b0ee7ed37601
+# Incorrect output on a LEFT JOIN.
+#
+do_execsql_test join5-3.1 {
+  DROP TABLE IF EXISTS t1;
+  DROP TABLE IF EXISTS t2;
+  DROP TABLE IF EXISTS t3;
+  CREATE TABLE x1(a);
+  INSERT INTO x1 VALUES(1);
+  CREATE TABLE x2(b NOT NULL);
+  CREATE TABLE x3(c, d);
+  INSERT INTO x3 VALUES('a', NULL);
+  INSERT INTO x3 VALUES('b', NULL);
+  INSERT INTO x3 VALUES('c', NULL);
+  SELECT * FROM x1 LEFT JOIN x2 LEFT JOIN x3 ON x3.d = x2.b;
+} {1 {} {} {}}
+do_execsql_test join5-3.2 {
+  DROP TABLE IF EXISTS t1;
+  DROP TABLE IF EXISTS t2;
+  DROP TABLE IF EXISTS t3;
+  DROP TABLE IF EXISTS t4;
+  DROP TABLE IF EXISTS t5;
+  CREATE TABLE t1(x text NOT NULL, y text);
+  CREATE TABLE t2(u text NOT NULL, x text NOT NULL);
+  CREATE TABLE t3(w text NOT NULL, v text);
+  CREATE TABLE t4(w text NOT NULL, z text NOT NULL);
+  CREATE TABLE t5(z text NOT NULL, m text);
+  INSERT INTO t1 VALUES('f6d7661f-4efe-4c90-87b5-858e61cd178b',NULL);
+  INSERT INTO t1 VALUES('f6ea82c3-2cad-45ce-ae8f-3ddca4fb2f48',NULL);
+  INSERT INTO t1 VALUES('f6f47499-ecb4-474b-9a02-35be73c235e5',NULL);
+  INSERT INTO t1 VALUES('56f47499-ecb4-474b-9a02-35be73c235e5',NULL);
+  INSERT INTO t3 VALUES('007f2033-cb20-494c-b135-a1e4eb66130c',
+                        'f6d7661f-4efe-4c90-87b5-858e61cd178b');
+  SELECT *
+    FROM t3
+         INNER JOIN t1 ON t1.x= t3.v AND t1.y IS NULL
+         LEFT JOIN t4  ON t4.w = t3.w
+         LEFT JOIN t5  ON t5.z = t4.z
+         LEFT JOIN t2  ON t2.u = t5.m
+         LEFT JOIN t1 xyz ON xyz.y = t2.x;
+} {007f2033-cb20-494c-b135-a1e4eb66130c f6d7661f-4efe-4c90-87b5-858e61cd178b f6d7661f-4efe-4c90-87b5-858e61cd178b {} {} {} {} {} {} {} {} {}}
+do_execsql_test join5-3.3 {
+  DROP TABLE IF EXISTS x1;
+  DROP TABLE IF EXISTS x2;
+  DROP TABLE IF EXISTS x3;
+  CREATE TABLE x1(a);
+  INSERT INTO x1 VALUES(1);
+  CREATE TABLE x2(b NOT NULL);
+  CREATE TABLE x3(c, d);
+  INSERT INTO x3 VALUES('a', NULL);
+  INSERT INTO x3 VALUES('b', NULL);
+  INSERT INTO x3 VALUES('c', NULL);
+  SELECT * FROM x1 LEFT JOIN x2 JOIN x3 WHERE x3.d = x2.b;
+} {}
 
 finish_test

Index: test/permutations.test
==================================================================
--- test/permutations.test
+++ test/permutations.test
@@ -111,10 +111,11 @@
   thread003.test thread004.test thread005.test trans2.test vacuum3.test 
   incrvacuum_ioerr.test autovacuum_crash.test btree8.test shared_err.test
   vtab_err.test walslow.test walcrash.test walcrash3.test
   walthread.test rtree3.test indexfault.test securedel2.test
   sort3.test sort4.test fts4growth.test fts4growth2.test
+  bigsort.test
 }]
 if {[info exists ::env(QUICKTEST_INCLUDE)]} {
   set allquicktests [concat $allquicktests $::env(QUICKTEST_INCLUDE)]
 }
 

Index: test/scanstatus.test
==================================================================
--- test/scanstatus.test
+++ test/scanstatus.test
@@ -266,11 +266,11 @@
 do_execsql_test    4.2.1 { DELETE FROM p1 WHERE x=4 }
 do_scanstatus_test 4.2.2 { 
   nLoop 1 nVisit 1 nEst 1.0 zName sqlite_autoindex_p1_1 
   zExplain {SEARCH TABLE p1 USING INDEX sqlite_autoindex_p1_1 (x=?)}
 
-  nLoop 1 nVisit 3 nEst 524288.0 zName c1 zExplain {SCAN TABLE c1}
+  nLoop 1 nVisit 3 nEst 262144.0 zName c1 zExplain {SCAN TABLE c1}
 }
 
 #-------------------------------------------------------------------------
 # Further tests of different scan types.
 #

ADDED   test/sharedB.test
Index: test/sharedB.test
==================================================================
--- /dev/null
+++ test/sharedB.test
@@ -0,0 +1,60 @@
+# 2014-12-05
+#
+# 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.
+#
+#***********************************************************************
+#
+# Open two database connections on the same database in shared cache
+# mode.  Hold one open while repeatedly closing, reopening, and using
+# the second.
+#
+# This test is designed to demostrate that the fix for ticket
+# [e4a18565a36884b00edf66541f38c693827968ab] works.  
+#
+
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+if {[run_thread_tests]==0} { finish_test ; return }
+db close
+set ::testprefix sharedB
+
+set ::enable_shared_cache [sqlite3_enable_shared_cache 1]
+
+#-------------------------------------------------------------------------
+#
+do_test 1.1 {
+  sqlite3 db1 test.db
+  sqlite3 db2 test.db
+
+  db1 eval {
+    CREATE TABLE t1(x,y TEXT COLLATE nocase);
+    WITH RECURSIVE
+      c(i) AS (VALUES(1) UNION ALL SELECT i+1 FROM c WHERE i<100)
+    INSERT INTO t1(x,y) SELECT i, printf('x%03dy',i) FROM c;
+    CREATE INDEX t1yx ON t1(y,x);
+  }
+  db2 eval {
+    SELECT x FROM t1 WHERE y='X014Y';
+  }
+} {14}
+
+for {set j 1} {$j<=100} {incr j} {
+  do_test 1.2.$j {
+    db2 close
+    sqlite3 db2 test.db
+    db2 eval {
+      SELECT x FROM t1 WHERE y='X014Y';
+    }
+  } {14}
+}
+
+db1 close
+db2 close
+sqlite3_enable_shared_cache $::enable_shared_cache
+finish_test

Index: test/shell1.test
==================================================================
--- test/shell1.test
+++ test/shell1.test
@@ -43,24 +43,25 @@
   set res [catchcmd "-bad test.db" ""]
   set rc [lindex $res 0]
   list $rc \
        [regexp {Error: unknown option: -bad} $res]
 } {1 1}
-# error on extra options
-do_test shell1-1.1.2 {
-  set res [catchcmd "-bad test.db \"select 3\" \"select 4\"" ""]
+do_test shell1-1.1.1b {
+  set res [catchcmd "test.db -bad" ""]
   set rc [lindex $res 0]
   list $rc \
-       [regexp {Error: too many options: "select 4"} $res]
+       [regexp {Error: unknown option: -bad} $res]
 } {1 1}
+# error on extra options
+do_test shell1-1.1.2 {
+  catchcmd "test.db \"select 3\" \"select 4\"" ""
+} {0 {3
+4}}
 # error on extra options
 do_test shell1-1.1.3 {
-  set res [catchcmd "-bad FOO test.db BAD" ".quit"]
-  set rc [lindex $res 0]
-  list $rc \
-       [regexp {Error: too many options: "BAD"} $res]
-} {1 1}
+  catchcmd "test.db FOO test.db BAD" ".quit"
+} {1 {Error: near "FOO": syntax error}}
 
 # -help
 do_test shell1-1.2.1 {
   set res [catchcmd "-help test.db" ""]
   set rc [lindex $res 0]
@@ -73,15 +74,15 @@
 # -init filename       read/process named file
 do_test shell1-1.3.1 {
   catchcmd "-init FOO test.db" ""
 } {0 {}}
 do_test shell1-1.3.2 {
-  set res [catchcmd "-init FOO test.db .quit BAD" ""]
-  set rc [lindex $res 0]
-  list $rc \
-       [regexp {Error: too many options: "BAD"} $res]
-} {1 1}
+  catchcmd "-init FOO test.db .quit BAD" ""
+} {0 {}}
+do_test shell1-1.3.3 {
+  catchcmd "-init FOO test.db BAD .quit" ""
+} {1 {Error: near "BAD": syntax error}}
 
 # -echo                print commands before execution
 do_test shell1-1.4.1 {
   catchcmd "-echo test.db" "" 
 } {0 {}}

Index: test/shell2.test
==================================================================
--- test/shell2.test
+++ test/shell2.test
@@ -50,13 +50,13 @@
 
 # Shell silently ignores extra parameters.
 # Ticket [f5cb008a65].
 do_test shell2-1.2.1 {
   set rc [catch { eval exec $CLI \":memory:\" \"select 3\" \"select 4\" } msg]
-  list $rc \
-       [regexp {Error: too many options: "select 4"} $msg]
-} {1 1}
+  list $rc $msg
+} {0 {3
+4}}
 
 # Test a problem reported on the mailing list. The shell was at one point
 # returning the generic SQLITE_ERROR message ("SQL error or missing database")
 # instead of the "too many levels..." message in the test below.
 #

Index: test/vtab1.test
==================================================================
--- test/vtab1.test
+++ test/vtab1.test
@@ -1392,7 +1392,49 @@
 } {1 2 3}
 
 do_execsql_test 21.3 {
   SELECT * FROM t9v WHERE a=b;
 } {2 2 2}
+
+#-------------------------------------------------------------------------
+# At one point executing a CREATE VIRTUAL TABLE statement that specified 
+# a database name but no virtual table arguments was causing an internal
+# buffer overread. Valgrind would report errors while running the following 
+# tests. Specifically:
+#
+#   CREATE VIRTUAL TABLE t1 USING fts4;          -- Ok - no db name.
+#   CREATE VIRTUAL TABLE main.t1 USING fts4(x);  -- Ok - has vtab arguments.
+#   CREATE VIRTUAL TABLE main.t1 USING fts4;     -- Had the problem. 
+#
+ifcapable fts3 {
+  forcedelete test.db2
+  set nm [string repeat abcdefghij 100]
+  do_execsql_test 22.1 {
+    ATTACH 'test.db2' AS $nm
+  }
+  
+  execsql "SELECT * FROM sqlite_master"
+  do_execsql_test 22.2 "CREATE VIRTUAL TABLE ${nm}.t1 USING fts4"
+  
+  do_test 22.3.1 {
+    set sql "CREATE VIRTUAL TABLE ${nm}.t2 USING fts4"
+    set stmt [sqlite3_prepare_v2 db $sql -1 dummy]
+    sqlite3_step $stmt
+  } {SQLITE_DONE}
+  
+  do_test 22.3.2 {
+    sqlite3_finalize $stmt
+  } {SQLITE_OK}
+  
+  do_test 22.4.1 {
+    set sql "CREATE VIRTUAL TABLE ${nm}.t3 USING fts4"
+    set n [string length $sql]
+    set stmt [sqlite3_prepare db "${sql}xyz" $n dummy]
+    sqlite3_step $stmt
+  } {SQLITE_DONE}
+  
+  do_test 22.4.2 {
+    sqlite3_finalize $stmt
+  } {SQLITE_OK}
+}
 
 finish_test

Index: test/wal5.test
==================================================================
--- test/wal5.test
+++ test/wal5.test
@@ -53,11 +53,12 @@
       array set a $args
       foreach key [array names a] {
         if {[lsearch {-mode -db} $key]<0} { error "unknown switch: $key" }
       }
 
-      if {$a(-mode)!="restart" && $a(-mode)!="full"} { set a(-mode) passive }
+      set vals {restart full truncate}
+      if {[lsearch -exact $vals $a(-mode)]<0} { set a(-mode) passive }
 
       set cmd [list sqlite3_wal_checkpoint_v2 $dbhandle $a(-mode)]
       if {[info exists a(-db)]} { lappend sql $a(-db) }
 
       uplevel $cmd
@@ -276,10 +277,15 @@
     7   RESTART   -   {0 4 4}   3
     8   RESTART   1   {1 3 3}   1
     9   RESTART   2   {1 4 3}   2
     10  RESTART   3   {1 4 4}   3
 
+    11  TRUNCATE  -   {0 0 0}   3
+    12  TRUNCATE  1   {1 3 3}   1
+    13  TRUNCATE  2   {1 4 3}   2
+    14  TRUNCATE  3   {1 4 4}   3
+
   } {
     do_multiclient_test tn {
       setup_and_attach_aux
 
       proc busyhandler {x} {
@@ -345,10 +351,45 @@
     code3 {sqlite3 db3 test.db}
 
     do_test 3.$tn.5 { sql3 { PRAGMA journal_mode } } {wal}
 
     do_test 3.$tn.6 { code3 { do_wal_checkpoint db3 } } {0 0 0}
+  }
+
+  # Test SQLITE_CHECKPOINT_TRUNCATE.
+  #
+  do_multiclient_test tn {
+
+    code1 $do_wal_checkpoint
+    code2 $do_wal_checkpoint
+    code3 $do_wal_checkpoint
+
+    do_test 3.$tn.1 {
+      sql1 {
+        PRAGMA page_size = 1024;
+        PRAGMA journal_mode = WAL;
+        PRAGMA synchronous = normal;
+        CREATE TABLE t1(x, y);
+        CREATE INDEX i1 ON t1(x, y);
+        INSERT INTO t1 VALUES(1, 2);
+        INSERT INTO t1 VALUES(3, 4);
+      }
+      file size test.db-wal
+    } [wal_file_size 8 1024]
+
+    do_test 3.$tn.2 { do_wal_checkpoint db -mode truncate } {0 0 0}
+    do_test 3.$tn.3 { file size test.db-wal } 0
+
+    do_test 3.$tn.4 {
+      sql2 { SELECT * FROM t1 }
+    } {1 2 3 4}
+
+    do_test 3.$tn.5 {
+      sql2 { INSERT INTO t1 VALUES('a', 'b') }
+      file size test.db-wal
+    } [wal_file_size 2 1024]
+
   }
 }
 
 
 finish_test

Index: test/whereJ.test
==================================================================
--- test/whereJ.test
+++ test/whereJ.test
@@ -636,8 +636,43 @@
      AND cx.type=2
      AND px.cx_id = cx.cx_id
      AND px.px_tid = 0
      AND px.le_id = le.le_id;
 } {/.*SCAN TABLE cx.*SEARCH TABLE px.*SEARCH TABLE le.*/}
+
+
+# The following test is derived from a performance problem reported from
+# the field.  Notice the multiple indexes with the same initial tables,
+# and the unusual WHERE clause terms.
+#
+do_test 5.1 {
+  set res [db eval {
+    DROP TABLE IF EXISTS t1;
+    CREATE TABLE t1(a,b,c,d,e,f,g,h);
+    CREATE INDEX t1abc ON t1(a,b,c);
+    CREATE INDEX t1abe ON t1(a,b,e);
+    CREATE INDEX t1abf ON t1(a,b,f);
+    ANALYZE;
+    DROP TABLE IF EXISTS sqlite_stat4;
+    DROP TABLE IF EXISTS sqlite_stat3;
+    DELETE FROM sqlite_stat1;
+    INSERT INTO sqlite_stat1(tbl,idx,stat)
+      VALUES('t1','t1abc','2000000 8000 1600 800'),
+            ('t1','t1abe','2000000 8000 1600 150'),
+            ('t1','t1abf','2000000 8000 1600 150');
+    ANALYZE sqlite_master;
+  
+    EXPLAIN QUERY PLAN
+    SELECT * FROM t1
+     WHERE (a=1 OR a=2)
+       AND (b=3 OR b=4)
+       AND (d>=5 AND d<=5)
+       AND ((e>=7 AND e<=7) OR (f>=8 AND f<=8))
+       AND g>0;
+  }]
+} {~/ANY/}
+do_test 5.2 {set res} {/USING INDEX t1abe/}
+do_test 5.3 {set res} {/USING INDEX t1abf/}
+
 
 
 finish_test