Improvements to the way that OOM errors are processed.

FossilOrigin-Name: c3ef03478a5788c855b3aef385d43ae7f494f440

27 files changed, 126 insertions, 87 deletions

diff --git a/src/alter.c b/src/alter.c
index 16b7a9e19..3419059fa 100644
--- a/src/alter.c
+++ b/src/alter.c
@@ -695,7 +695,7 @@ void sqlite3AlterFinishAddColumn(Parse *pParse, Token *pColDef){
     rc = sqlite3ValueFromExpr(db, pDflt, SQLITE_UTF8, SQLITE_AFF_BLOB, &pVal);
     assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
     if( rc!=SQLITE_OK ){
-      db->mallocFailed = 1;
+      assert( db->mallocFailed = 1 );
       return;
     }
     if( !pVal ){
diff --git a/src/analyze.c b/src/analyze.c
index 4d777fa9f..7a7d68f59 100644
--- a/src/analyze.c
+++ b/src/analyze.c
@@ -1523,7 +1523,7 @@ static int analysisLoader(void *pData, int argc, char **argv, char **NotUsed){
     ** the old data with the new instead of allocating a new array.  */
     if( pIndex->aiRowEst==0 ){
       pIndex->aiRowEst = (tRowcnt*)sqlite3MallocZero(sizeof(tRowcnt) * nCol);
-      if( pIndex->aiRowEst==0 ) pInfo->db->mallocFailed = 1;
+      if( pIndex->aiRowEst==0 ) sqlite3OomFault(pInfo->db);
     }
     aiRowEst = pIndex->aiRowEst;
 #endif
@@ -1670,7 +1670,7 @@ static int loadStatTbl(
   Index *pPrevIdx = 0;          /* Previous index in the loop */
   IndexSample *pSample;         /* A slot in pIdx->aSample[] */
 
-  assert( db->lookaside.bEnabled==0 );
+  assert( db->lookaside.bDisable );
   zSql = sqlite3MPrintf(db, zSql1, zDb);
   if( !zSql ){
     return SQLITE_NOMEM;
@@ -1784,7 +1784,7 @@ static int loadStatTbl(
 static int loadStat4(sqlite3 *db, const char *zDb){
   int rc = SQLITE_OK;             /* Result codes from subroutines */
 
-  assert( db->lookaside.bEnabled==0 );
+  assert( db->lookaside.bDisable );
   if( sqlite3FindTable(db, "sqlite_stat4", zDb) ){
     rc = loadStatTbl(db, 0,
       "SELECT idx,count(*) FROM %Q.sqlite_stat4 GROUP BY idx", 
@@ -1866,10 +1866,9 @@ int sqlite3AnalysisLoad(sqlite3 *db, int iDb){
   /* Load the statistics from the sqlite_stat4 table. */
 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
   if( rc==SQLITE_OK && OptimizationEnabled(db, SQLITE_Stat34) ){
-    int lookasideEnabled = db->lookaside.bEnabled;
-    db->lookaside.bEnabled = 0;
+    db->lookaside.bDisable++;
     rc = loadStat4(db, sInfo.zDatabase);
-    db->lookaside.bEnabled = lookasideEnabled;
+    db->lookaside.bDisable--;
   }
   for(i=sqliteHashFirst(&db->aDb[iDb].pSchema->idxHash);i;i=sqliteHashNext(i)){
     Index *pIdx = sqliteHashData(i);
@@ -1879,7 +1878,7 @@ int sqlite3AnalysisLoad(sqlite3 *db, int iDb){
 #endif
 
   if( rc==SQLITE_NOMEM ){
-    db->mallocFailed = 1;
+    sqlite3OomFault(db);
   }
   return rc;
 }
diff --git a/src/attach.c b/src/attach.c
index 12d3ac3ff..e167951f6 100644
--- a/src/attach.c
+++ b/src/attach.c
@@ -127,7 +127,7 @@ static void attachFunc(
   flags = db->openFlags;
   rc = sqlite3ParseUri(db->pVfs->zName, zFile, &flags, &pVfs, &zPath, &zErr);
   if( rc!=SQLITE_OK ){
-    if( rc==SQLITE_NOMEM ) db->mallocFailed = 1;
+    if( rc==SQLITE_NOMEM ) sqlite3OomFault(db);
     sqlite3_result_error(context, zErr, -1);
     sqlite3_free(zErr);
     return;
@@ -230,7 +230,7 @@ static void attachFunc(
     sqlite3ResetAllSchemasOfConnection(db);
     db->nDb = iDb;
     if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
-      db->mallocFailed = 1;
+      sqlite3OomFault(db);
       sqlite3DbFree(db, zErrDyn);
       zErrDyn = sqlite3MPrintf(db, "out of memory");
     }else if( zErrDyn==0 ){
diff --git a/src/build.c b/src/build.c
index cea05d51c..097149fd4 100644
--- a/src/build.c
+++ b/src/build.c
@@ -78,7 +78,7 @@ void sqlite3TableLock(
     p->zName = zName;
   }else{
     pToplevel->nTableLock = 0;
-    pToplevel->db->mallocFailed = 1;
+    sqlite3OomFault(pToplevel->db);
   }
 }
 
@@ -1555,7 +1555,7 @@ static char *createTableStmt(sqlite3 *db, Table *p){
   n += 35 + 6*p->nCol;
   zStmt = sqlite3DbMallocRaw(0, n);
   if( zStmt==0 ){
-    db->mallocFailed = 1;
+    sqlite3OomFault(db);
     return 0;
   }
   sqlite3_snprintf(n, zStmt, "CREATE TABLE ");
@@ -2038,7 +2038,7 @@ void sqlite3EndTable(
     pOld = sqlite3HashInsert(&pSchema->tblHash, p->zName, p);
     if( pOld ){
       assert( p==pOld );  /* Malloc must have failed inside HashInsert() */
-      db->mallocFailed = 1;
+      sqlite3OomFault(db);
       return;
     }
     pParse->pNewTable = 0;
@@ -2142,7 +2142,6 @@ int sqlite3ViewGetColumnNames(Parse *pParse, Table *pTable){
   int n;            /* Temporarily holds the number of cursors assigned */
   sqlite3 *db = pParse->db;  /* Database connection for malloc errors */
   sqlite3_xauth xAuth;       /* Saved xAuth pointer */
-  u8 bEnabledLA;             /* Saved db->lookaside.bEnabled state */
 
   assert( pTable );
 
@@ -2188,18 +2187,18 @@ int sqlite3ViewGetColumnNames(Parse *pParse, Table *pTable){
   ** statement that defines the view.
   */
   assert( pTable->pSelect );
-  bEnabledLA = db->lookaside.bEnabled;
   if( pTable->pCheck ){
-    db->lookaside.bEnabled = 0;
+    db->lookaside.bDisable++;
     sqlite3ColumnsFromExprList(pParse, pTable->pCheck, 
                                &pTable->nCol, &pTable->aCol);
+    db->lookaside.bDisable--;
   }else{
     pSel = sqlite3SelectDup(db, pTable->pSelect, 0);
     if( pSel ){
       n = pParse->nTab;
       sqlite3SrcListAssignCursors(pParse, pSel->pSrc);
       pTable->nCol = -1;
-      db->lookaside.bEnabled = 0;
+      db->lookaside.bDisable++;
 #ifndef SQLITE_OMIT_AUTHORIZATION
       xAuth = db->xAuth;
       db->xAuth = 0;
@@ -2208,6 +2207,7 @@ int sqlite3ViewGetColumnNames(Parse *pParse, Table *pTable){
 #else
       pSelTab = sqlite3ResultSetOfSelect(pParse, pSel);
 #endif
+      db->lookaside.bDisable--;
       pParse->nTab = n;
       if( pSelTab ){
         assert( pTable->aCol==0 );
@@ -2226,7 +2226,6 @@ int sqlite3ViewGetColumnNames(Parse *pParse, Table *pTable){
       nErr++;
     }
   }
-  db->lookaside.bEnabled = bEnabledLA;
   pTable->pSchema->schemaFlags |= DB_UnresetViews;
 #endif /* SQLITE_OMIT_VIEW */
   return nErr;  
@@ -2692,7 +2691,7 @@ void sqlite3CreateForeignKey(
       pFKey->zTo, (void *)pFKey
   );
   if( pNextTo==pFKey ){
-    db->mallocFailed = 1;
+    sqlite3OomFault(db);
     goto fk_end;
   }
   if( pNextTo ){
@@ -3274,7 +3273,7 @@ Index *sqlite3CreateIndex(
                           pIndex->zName, pIndex);
     if( p ){
       assert( p==pIndex );  /* Malloc must have failed */
-      db->mallocFailed = 1;
+      sqlite3OomFault(db);
       goto exit_create_index;
     }
     db->flags |= SQLITE_InternChanges;
@@ -3992,7 +3991,7 @@ int sqlite3OpenTempDatabase(Parse *pParse){
     db->aDb[1].pBt = pBt;
     assert( db->aDb[1].pSchema );
     if( SQLITE_NOMEM==sqlite3BtreeSetPageSize(pBt, db->nextPagesize, -1, 0) ){
-      db->mallocFailed = 1;
+      sqlite3OomFault(db);
       return 1;
     }
   }
diff --git a/src/callback.c b/src/callback.c
index 2a9f5b802..2b955fdcd 100644
--- a/src/callback.c
+++ b/src/callback.c
@@ -177,7 +177,7 @@ static CollSeq *findCollSeqEntry(
       */
       assert( pDel==0 || pDel==pColl );
       if( pDel!=0 ){
-        db->mallocFailed = 1;
+        sqlite3OomFault(db);
         sqlite3DbFree(db, pDel);
         pColl = 0;
       }
@@ -465,7 +465,7 @@ Schema *sqlite3SchemaGet(sqlite3 *db, Btree *pBt){
     p = (Schema *)sqlite3DbMallocZero(0, sizeof(Schema));
   }
   if( !p ){
-    db->mallocFailed = 1;
+    sqlite3OomFault(db);
   }else if ( 0==p->file_format ){
     sqlite3HashInit(&p->tblHash);
     sqlite3HashInit(&p->idxHash);
diff --git a/src/expr.c b/src/expr.c
index c91db2834..5b134d666 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -699,7 +699,10 @@ void sqlite3ExprAssignVarNumber(Parse *pParse, Expr *pExpr){
       if( x>pParse->nzVar ){
         char **a;
         a = sqlite3DbRealloc(db, pParse->azVar, x*sizeof(a[0]));
-        if( a==0 ) return;  /* Error reported through db->mallocFailed */
+        if( a==0 ){
+          assert( db->mallocFailed ); /* Error reported through mallocFailed */
+          return;
+        }
         pParse->azVar = a;
         memset(&a[pParse->nzVar], 0, (x-pParse->nzVar)*sizeof(a[0]));
         pParse->nzVar = x;
diff --git a/src/fkey.c b/src/fkey.c
index 7eb188924..fae25c482 100644
--- a/src/fkey.c
+++ b/src/fkey.c
@@ -1165,7 +1165,6 @@ static Trigger *fkActionTrigger(
   pTrigger = pFKey->apTrigger[iAction];
 
   if( action!=OE_None && !pTrigger ){
-    u8 enableLookaside;           /* Copy of db->lookaside.bEnabled */
     char const *zFrom;            /* Name of child table */
     int nFrom;                    /* Length in bytes of zFrom */
     Index *pIdx = 0;              /* Parent key index for this FK */
@@ -1274,8 +1273,7 @@ static Trigger *fkActionTrigger(
     }
 
     /* Disable lookaside memory allocation */
-    enableLookaside = db->lookaside.bEnabled;
-    db->lookaside.bEnabled = 0;
+    db->lookaside.bDisable++;
 
     pTrigger = (Trigger *)sqlite3DbMallocZero(db, 
         sizeof(Trigger) +         /* struct Trigger */
@@ -1297,7 +1295,7 @@ static Trigger *fkActionTrigger(
     }
 
     /* Re-enable the lookaside buffer, if it was disabled earlier. */
-    db->lookaside.bEnabled = enableLookaside;
+    db->lookaside.bDisable--;
 
     sqlite3ExprDelete(db, pWhere);
     sqlite3ExprDelete(db, pWhen);
diff --git a/src/func.c b/src/func.c
index 982a8c2ca..d615cf90b 100644
--- a/src/func.c
+++ b/src/func.c
@@ -1615,7 +1615,7 @@ void sqlite3RegisterBuiltinFunctions(sqlite3 *db){
   int rc = sqlite3_overload_function(db, "MATCH", 2);
   assert( rc==SQLITE_NOMEM || rc==SQLITE_OK );
   if( rc==SQLITE_NOMEM ){
-    db->mallocFailed = 1;
+    sqlite3OomFault(db);
   }
 }
 
diff --git a/src/insert.c b/src/insert.c
index 5f36c089f..a8cde7295 100644
--- a/src/insert.c
+++ b/src/insert.c
@@ -83,7 +83,7 @@ const char *sqlite3IndexAffinityStr(sqlite3 *db, Index *pIdx){
     Table *pTab = pIdx->pTable;
     pIdx->zColAff = (char *)sqlite3DbMallocRaw(0, pIdx->nColumn+1);
     if( !pIdx->zColAff ){
-      db->mallocFailed = 1;
+      sqlite3OomFault(db);
       return 0;
     }
     for(n=0; n<pIdx->nColumn; n++){
@@ -134,7 +134,7 @@ void sqlite3TableAffinity(Vdbe *v, Table *pTab, int iReg){
     sqlite3 *db = sqlite3VdbeDb(v);
     zColAff = (char *)sqlite3DbMallocRaw(0, pTab->nCol+1);
     if( !zColAff ){
-      db->mallocFailed = 1;
+      sqlite3OomFault(db);
       return;
     }
 
diff --git a/src/legacy.c b/src/legacy.c
index a10006e55..1b5e518d4 100644
--- a/src/legacy.c
+++ b/src/legacy.c
@@ -90,7 +90,7 @@ int sqlite3_exec(
           for(i=0; i<nCol; i++){
             azVals[i] = (char *)sqlite3_column_text(pStmt, i);
             if( !azVals[i] && sqlite3_column_type(pStmt, i)!=SQLITE_NULL ){
-              db->mallocFailed = 1;
+              sqlite3OomFault(db);
               goto exec_out;
             }
           }
diff --git a/src/main.c b/src/main.c
index 63a105c3f..588461b48 100644
--- a/src/main.c
+++ b/src/main.c
@@ -698,12 +698,12 @@ static int setupLookaside(sqlite3 *db, void *pBuf, int sz, int cnt){
       p = (LookasideSlot*)&((u8*)p)[sz];
     }
     db->lookaside.pEnd = p;
-    db->lookaside.bEnabled = 1;
+    db->lookaside.bDisable = 0;
     db->lookaside.bMalloced = pBuf==0 ?1:0;
   }else{
     db->lookaside.pStart = db;
     db->lookaside.pEnd = db;
-    db->lookaside.bEnabled = 0;
+    db->lookaside.bDisable = 1;
     db->lookaside.bMalloced = 0;
   }
 #endif /* SQLITE_OMIT_LOOKASIDE */
@@ -2208,7 +2208,7 @@ const void *sqlite3_errmsg16(sqlite3 *db){
     ** be cleared before returning. Do this directly, instead of via
     ** sqlite3ApiExit(), to avoid setting the database handle error message.
     */
-    db->mallocFailed = 0;
+    sqlite3OomClear(db);
   }
   sqlite3_mutex_leave(db->mutex);
   return z;
@@ -2846,7 +2846,7 @@ static int openDatabase(
   db->openFlags = flags;
   rc = sqlite3ParseUri(zVfs, zFilename, &flags, &db->pVfs, &zOpen, &zErrMsg);
   if( rc!=SQLITE_OK ){
-    if( rc==SQLITE_NOMEM ) db->mallocFailed = 1;
+    if( rc==SQLITE_NOMEM ) sqlite3OomFault(db);
     sqlite3ErrorWithMsg(db, rc, zErrMsg ? "%s" : 0, zErrMsg);
     sqlite3_free(zErrMsg);
     goto opendb_out;
diff --git a/src/malloc.c b/src/malloc.c
index c8a04128c..057d36a4b 100644
--- a/src/malloc.c
+++ b/src/malloc.c
@@ -608,10 +608,8 @@ void *sqlite3DbMallocRaw(sqlite3 *db, u64 n){
 #ifndef SQLITE_OMIT_LOOKASIDE
   if( db ){
     LookasideSlot *pBuf;
-    if( db->mallocFailed ){
-      return 0;
-    }
-    if( db->lookaside.bEnabled ){
+    if( db->lookaside.bDisable==0 ){
+      assert( db->mallocFailed==0 );
       if( n>db->lookaside.sz ){
         db->lookaside.anStat[1]++;
       }else if( (pBuf = db->lookaside.pFree)==0 ){
@@ -625,7 +623,10 @@ void *sqlite3DbMallocRaw(sqlite3 *db, u64 n){
         }
         return (void*)pBuf;
       }
+    }else if( db->mallocFailed ){
+      return 0;
     }
+    
   }
 #else
   if( db && db->mallocFailed ){
@@ -637,10 +638,10 @@ void *sqlite3DbMallocRaw(sqlite3 *db, u64 n){
 static SQLITE_NOINLINE void *dbMallocRawFinish(sqlite3 *db, u64 n){
   void *p = sqlite3Malloc(n);
   if( !p && db ){
-    db->mallocFailed = 1;
+    sqlite3OomFault(db);
   }
   sqlite3MemdebugSetType(p, 
-         (db && db->lookaside.bEnabled) ? MEMTYPE_LOOKASIDE : MEMTYPE_HEAP);
+         (db && db->lookaside.bDisable==0) ? MEMTYPE_LOOKASIDE : MEMTYPE_HEAP);
   return p;
 }
 
@@ -671,10 +672,10 @@ void *sqlite3DbRealloc(sqlite3 *db, void *p, u64 n){
       sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
       pNew = sqlite3_realloc64(p, n);
       if( !pNew ){
-        db->mallocFailed = 1;
+        sqlite3OomFault(db);
       }
       sqlite3MemdebugSetType(pNew,
-            (db->lookaside.bEnabled ? MEMTYPE_LOOKASIDE : MEMTYPE_HEAP));
+            (db->lookaside.bDisable==0 ? MEMTYPE_LOOKASIDE : MEMTYPE_HEAP));
     }
   }
   return pNew;
@@ -737,10 +738,42 @@ void sqlite3SetString(char **pz, sqlite3 *db, const char *zNew){
 }
 
 /*
+** Call this routine to record the fact that an OOM (out-of-memory) error
+** has happened.  This routine will set db->mallocFailed, and also
+** temporarily disable the lookaside memory allocator and interrupt
+** any running VDBEs.
+*/
+void sqlite3OomFault(sqlite3 *db){
+  if( db->mallocFailed==0 && db->bBenignMalloc==0 ){
+    db->mallocFailed = 1;
+    if( db->nVdbeExec>0 ){
+      db->u1.isInterrupted = 1;
+    }
+    db->lookaside.bDisable++;
+  }
+}
+
+/*
+** This routine reactivates the memory allocator and clears the
+** db->mallocFailed flag as necessary.
+**
+** The memory allocator is not restarted if there are running
+** VDBEs.
+*/
+void sqlite3OomClear(sqlite3 *db){
+  if( db->mallocFailed && db->nVdbeExec==0 ){
+    db->mallocFailed = 0;
+    db->u1.isInterrupted = 0;
+    assert( db->lookaside.bDisable>0 );
+    db->lookaside.bDisable--;
+  }
+}
+
+/*
 ** Take actions at the end of an API call to indicate an OOM error
 */
 static SQLITE_NOINLINE int apiOomError(sqlite3 *db){
-  db->mallocFailed = 0;
+  sqlite3OomClear(db);
   sqlite3Error(db, SQLITE_NOMEM);
   return SQLITE_NOMEM;
 }
diff --git a/src/parse.y b/src/parse.y
index 846c2504b..0bfe4e473 100644
--- a/src/parse.y
+++ b/src/parse.y
@@ -106,6 +106,15 @@ struct TrigEvent { int a; IdList * b; };
 */
 struct AttachKey { int type;  Token key; };
 
+/*
+** Disable lookaside memory allocation for objects that might be
+** shared across database connections.
+*/
+static void disableLookaside(Parse *pParse){
+  pParse->disableLookaside++;
+  pParse->db->lookaside.bDisable++;
+}
+
 } // end %include
 
 // Input is a single SQL command
@@ -156,7 +165,7 @@ create_table ::= createkw temp(T) TABLE ifnotexists(E) nm(Y) dbnm(Z). {
    sqlite3StartTable(pParse,&Y,&Z,T,0,0,E);
 }
 createkw(A) ::= CREATE(X).  {
-  pParse->db->lookaside.bEnabled = 0;
+  disableLookaside(pParse);
   A = X;
 }
 %type ifnotexists {int}
@@ -1507,7 +1516,7 @@ cmd ::= ALTER TABLE add_column_fullname ADD kwcolumn_opt column(Y). {
   sqlite3AlterFinishAddColumn(pParse, &Y);
 }
 add_column_fullname ::= fullname(X). {
-  pParse->db->lookaside.bEnabled = 0;
+  disableLookaside(pParse);
   sqlite3AlterBeginAddColumn(pParse, X);
 }
 kwcolumn_opt ::= .
diff --git a/src/pragma.c b/src/pragma.c
index bde17d1e8..c34d5421c 100644
--- a/src/pragma.c
+++ b/src/pragma.c
@@ -478,7 +478,7 @@ void sqlite3Pragma(
       */
       db->nextPagesize = sqlite3Atoi(zRight);
       if( SQLITE_NOMEM==sqlite3BtreeSetPageSize(pBt, db->nextPagesize,-1,0) ){
-        db->mallocFailed = 1;
+        sqlite3OomFault(db);
       }
     }
     break;
diff --git a/src/prepare.c b/src/prepare.c
index f8ad54665..3fb71a770 100644
--- a/src/prepare.c
+++ b/src/prepare.c
@@ -32,7 +32,7 @@ static void corruptSchema(
     if( z && zExtra ) z = sqlite3_mprintf("%z - %s", z, zExtra);
     sqlite3DbFree(db, *pData->pzErrMsg);
     *pData->pzErrMsg = z;
-    if( z==0 ) db->mallocFailed = 1;
+    if( z==0 ) sqlite3OomFault(db);
   }
   pData->rc = db->mallocFailed ? SQLITE_NOMEM : SQLITE_CORRUPT_BKPT;
 }
@@ -91,7 +91,7 @@ int sqlite3InitCallback(void *pInit, int argc, char **argv, char **NotUsed){
       }else{
         pData->rc = rc;
         if( rc==SQLITE_NOMEM ){
-          db->mallocFailed = 1;
+          sqlite3OomFault(db);
         }else if( rc!=SQLITE_INTERRUPT && (rc&0xFF)!=SQLITE_LOCKED ){
           corruptSchema(pData, argv[0], sqlite3_errmsg(db));
         }
@@ -336,7 +336,7 @@ initone_error_out:
 
 error_out:
   if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
-    db->mallocFailed = 1;
+    sqlite3OomFault(db);
   }
   return rc;
 }
@@ -434,7 +434,7 @@ static void schemaIsValid(Parse *pParse){
     if( !sqlite3BtreeIsInReadTrans(pBt) ){
       rc = sqlite3BtreeBeginTrans(pBt, 0);
       if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
-        db->mallocFailed = 1;
+        sqlite3OomFault(db);
       }
       if( rc!=SQLITE_OK ) return;
       openedTransaction = 1;
@@ -497,6 +497,11 @@ void sqlite3ParserReset(Parse *pParse){
     sqlite3 *db = pParse->db;
     sqlite3DbFree(db, pParse->aLabel);
     sqlite3ExprListDelete(db, pParse->pConstExpr);
+    if( db ){
+      assert( db->lookaside.bDisable >= pParse->disableLookaside );
+      db->lookaside.bDisable -= pParse->disableLookaside;
+    }
+    pParse->disableLookaside = 0;
   }
 }
 
@@ -592,9 +597,6 @@ static int sqlite3Prepare(
   }
   assert( 0==pParse->nQueryLoop );
 
-  if( db->mallocFailed ){
-    pParse->rc = SQLITE_NOMEM;
-  }
   if( pParse->rc==SQLITE_DONE ) pParse->rc = SQLITE_OK;
   if( pParse->checkSchema ){
     schemaIsValid(pParse);
@@ -716,7 +718,7 @@ int sqlite3Reprepare(Vdbe *p){
   rc = sqlite3LockAndPrepare(db, zSql, -1, 0, p, &pNew, 0);
   if( rc ){
     if( rc==SQLITE_NOMEM ){
-      db->mallocFailed = 1;
+      sqlite3OomFault(db);
     }
     assert( pNew==0 );
     return rc;
diff --git a/src/printf.c b/src/printf.c
index 946161f64..238997f37 100644
--- a/src/printf.c
+++ b/src/printf.c
@@ -929,7 +929,7 @@ char *sqlite3VMPrintf(sqlite3 *db, const char *zFormat, va_list ap){
   sqlite3VXPrintf(&acc, zFormat, ap);
   z = sqlite3StrAccumFinish(&acc);
   if( acc.accError==STRACCUM_NOMEM ){
-    db->mallocFailed = 1;
+    sqlite3OomFault(db);
   }
   return z;
 }
diff --git a/src/select.c b/src/select.c
index 891b12354..84d5423de 100644
--- a/src/select.c
+++ b/src/select.c
@@ -1016,7 +1016,7 @@ KeyInfo *sqlite3KeyInfoAlloc(sqlite3 *db, int N, int X){
     p->nRef = 1;
     memset(&p[1], 0, nExtra);
   }else{
-    db->mallocFailed = 1;
+    sqlite3OomFault(db);
   }
   return p;
 }
@@ -1677,7 +1677,7 @@ int sqlite3ColumnsFromExprList(
     pCol->zName = zName;
     sqlite3ColumnPropertiesFromName(0, pCol);
     if( zName && sqlite3HashInsert(&ht, zName, pCol)==pCol ){
-      db->mallocFailed = 1;
+      sqlite3OomFault(db);
     }
   }
   sqlite3HashClear(&ht);
@@ -1764,7 +1764,7 @@ Table *sqlite3ResultSetOfSelect(Parse *pParse, Select *pSelect){
   }
   /* The sqlite3ResultSetOfSelect() is only used n contexts where lookaside
   ** is disabled */
-  assert( db->lookaside.bEnabled==0 );
+  assert( db->lookaside.bDisable );
   pTab->nRef = 1;
   pTab->zName = 0;
   pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) );
@@ -5562,7 +5562,8 @@ int sqlite3Select(
         if( flag ){
           pMinMax = sqlite3ExprListDup(db, pMinMax, 0);
           pDel = pMinMax;
-          if( pMinMax && !db->mallocFailed ){
+          assert( db->mallocFailed || pMinMax!=0 );
+          if( !db->mallocFailed ){
             pMinMax->a[0].sortOrder = flag!=WHERE_ORDERBY_MIN ?1:0;
             pMinMax->a[0].pExpr->op = TK_COLUMN;
           }
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 16d3ea992..70f210c0a 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -1094,8 +1094,8 @@ struct Schema {
 ** lookaside allocations are not used to construct the schema objects.
 */
 struct Lookaside {
+  u32 bDisable;           /* Only operate the lookaside when zero */
   u16 sz;                 /* Size of each buffer in bytes */
-  u8 bEnabled;            /* False to disable new lookaside allocations */
   u8 bMalloced;           /* True if pStart obtained from sqlite3_malloc() */
   int nOut;               /* Number of buffers currently checked out */
   int mxOut;              /* Highwater mark for nOut */
@@ -1178,6 +1178,7 @@ struct sqlite3 {
   u8 autoCommit;                /* The auto-commit flag. */
   u8 temp_store;                /* 1: file 2: memory 0: default */
   u8 mallocFailed;              /* True if we have seen a malloc failure */
+  u8 bBenignMalloc;             /* Do not require OOMs if true */
   u8 dfltLockMode;              /* Default locking-mode for attached dbs */
   signed char nextAutovac;      /* Autovac setting after VACUUM if >=0 */
   u8 suppressErr;               /* Do not issue error messages if true */
@@ -2733,6 +2734,7 @@ struct Parse {
   u8 mayAbort;         /* True if statement may throw an ABORT exception */
   u8 hasCompound;      /* Need to invoke convertCompoundSelectToSubquery() */
   u8 okConstFactor;    /* OK to factor out constants */
+  u8 disableLookaside; /* Number of times lookaside has been disabled */
   int aTempReg[8];     /* Holding area for temporary registers */
   int nRangeReg;       /* Size of the temporary register block */
   int iRangeReg;       /* First register in temporary register block */
@@ -3777,6 +3779,8 @@ int sqlite3CreateFunc(sqlite3 *, const char *, int, int, void *,
   void (*)(sqlite3_context*,int,sqlite3_value **), void (*)(sqlite3_context*),
   FuncDestructor *pDestructor
 );
+void sqlite3OomFault(sqlite3*);
+void sqlite3OomClear(sqlite3*);
 int sqlite3ApiExit(sqlite3 *db, int);
 int sqlite3OpenTempDatabase(Parse *);
 
diff --git a/src/tokenize.c b/src/tokenize.c
index b85e35dc1..5bee3d5a8 100644
--- a/src/tokenize.c
+++ b/src/tokenize.c
@@ -390,7 +390,6 @@ int sqlite3RunParser(Parse *pParse, const char *zSql, char **pzErrMsg){
   void *pEngine;                  /* The LEMON-generated LALR(1) parser */
   int tokenType;                  /* type of the next token */
   int lastTokenParsed = -1;       /* type of the previous token */
-  u8 enableLookaside;             /* Saved value of db->lookaside.bEnabled */
   sqlite3 *db = pParse->db;       /* The database connection */
   int mxSqlLen;                   /* Max length of an SQL string */
 
@@ -406,7 +405,7 @@ int sqlite3RunParser(Parse *pParse, const char *zSql, char **pzErrMsg){
   /* sqlite3ParserTrace(stdout, "parser: "); */
   pEngine = sqlite3ParserAlloc(sqlite3Malloc);
   if( pEngine==0 ){
-    db->mallocFailed = 1;
+    sqlite3OomFault(db);
     return SQLITE_NOMEM;
   }
   assert( pParse->pNewTable==0 );
@@ -414,8 +413,6 @@ int sqlite3RunParser(Parse *pParse, const char *zSql, char **pzErrMsg){
   assert( pParse->nVar==0 );
   assert( pParse->nzVar==0 );
   assert( pParse->azVar==0 );
-  enableLookaside = db->lookaside.bEnabled;
-  if( db->lookaside.pStart ) db->lookaside.bEnabled = 1;
   while( zSql[i]!=0 ){
     assert( i>=0 );
     pParse->sLastToken.z = &zSql[i];
@@ -428,7 +425,6 @@ int sqlite3RunParser(Parse *pParse, const char *zSql, char **pzErrMsg){
     if( tokenType>=TK_SPACE ){
       assert( tokenType==TK_SPACE || tokenType==TK_ILLEGAL );
       if( db->u1.isInterrupted ){
-        sqlite3ErrorMsg(pParse, "interrupt");
         pParse->rc = SQLITE_INTERRUPT;
         break;
       }
@@ -463,7 +459,6 @@ int sqlite3RunParser(Parse *pParse, const char *zSql, char **pzErrMsg){
   sqlite3_mutex_leave(sqlite3MallocMutex());
 #endif /* YYDEBUG */
   sqlite3ParserFree(pEngine, sqlite3_free);
-  db->lookaside.bEnabled = enableLookaside;
   if( db->mallocFailed ){
     pParse->rc = SQLITE_NOMEM;
   }
diff --git a/src/trigger.c b/src/trigger.c
index 4bfb55af6..72c31eb2a 100644
--- a/src/trigger.c
+++ b/src/trigger.c
@@ -323,7 +323,7 @@ void sqlite3FinishTrigger(
     assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
     pTrig = sqlite3HashInsert(pHash, zName, pTrig);
     if( pTrig ){
-      db->mallocFailed = 1;
+      sqlite3OomFault(db);
     }else if( pLink->pSchema==pLink->pTabSchema ){
       Table *pTab;
       pTab = sqlite3HashFind(&pLink->pTabSchema->tblHash, pLink->table);
diff --git a/src/vdbe.c b/src/vdbe.c
index 62ad86d4f..c0eff6a09 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -629,7 +629,6 @@ int sqlite3VdbeExec(
 #endif
   for(pOp=&aOp[p->pc]; rc==SQLITE_OK; pOp++){
     assert( pOp>=aOp && pOp<&aOp[p->nOp]);
-    if( db->mallocFailed ) goto no_mem;
 #ifdef VDBE_PROFILE
     start = sqlite3Hwtime();
 #endif
@@ -6785,7 +6784,7 @@ vdbe_error_halt:
   sqlite3_log(rc, "statement aborts at %d: [%s] %s", 
                    (int)(pOp - aOp), p->zSql, p->zErrMsg);
   sqlite3VdbeHalt(p);
-  if( rc==SQLITE_IOERR_NOMEM ) db->mallocFailed = 1;
+  if( rc==SQLITE_IOERR_NOMEM ) sqlite3OomFault(db);
   rc = SQLITE_ERROR;
   if( resetSchemaOnFault>0 ){
     sqlite3ResetOneSchema(db, resetSchemaOnFault-1);
@@ -6815,7 +6814,7 @@ too_big:
   /* Jump to here if a malloc() fails.
   */
 no_mem:
-  db->mallocFailed = 1;
+  sqlite3OomFault(db);
   sqlite3VdbeError(p, "out of memory");
   rc = SQLITE_NOMEM;
   goto vdbe_error_halt;
@@ -6836,7 +6835,7 @@ abort_due_to_error:
   */
 abort_due_to_interrupt:
   assert( db->u1.isInterrupted );
-  rc = SQLITE_INTERRUPT;
+  rc = db->mallocFailed ? SQLITE_NOMEM : SQLITE_INTERRUPT;
   p->rc = rc;
   sqlite3VdbeError(p, "%s", sqlite3ErrStr(rc));
   goto vdbe_error_halt;
diff --git a/src/vdbeapi.c b/src/vdbeapi.c
index 0a15633dd..fce43630e 100644
--- a/src/vdbeapi.c
+++ b/src/vdbeapi.c
@@ -473,7 +473,7 @@ void sqlite3_result_error_nomem(sqlite3_context *pCtx){
   sqlite3VdbeMemSetNull(pCtx->pOut);
   pCtx->isError = SQLITE_NOMEM;
   pCtx->fErrorOrAux = 1;
-  pCtx->pOut->db->mallocFailed = 1;
+  sqlite3OomFault(pCtx->pOut->db);
 }
 
 /*
@@ -1101,7 +1101,7 @@ static const void *columnName(
     ** is the case, clear the mallocFailed flag and return NULL.
     */
     if( db->mallocFailed ){
-      db->mallocFailed = 0;
+      sqlite3OomClear(db);
       ret = 0;
     }
     sqlite3_mutex_leave(db->mutex);
diff --git a/src/vdbeaux.c b/src/vdbeaux.c
index 632c1231a..7d3a8c429 100644
--- a/src/vdbeaux.c
+++ b/src/vdbeaux.c
@@ -1423,7 +1423,6 @@ static void releaseMemArray(Mem *p, int N){
   if( p && N ){
     Mem *pEnd = &p[N];
     sqlite3 *db = p->db;
-    u8 malloc_failed = db->mallocFailed;
     if( db->pnBytesFreed ){
       do{
         if( p->szMalloc ) sqlite3DbFree(db, p->zMalloc);
@@ -1459,7 +1458,6 @@ static void releaseMemArray(Mem *p, int N){
 
       p->flags = MEM_Undefined;
     }while( (++p)<pEnd );
-    db->mallocFailed = malloc_failed;
   }
 }
 
@@ -1520,7 +1518,7 @@ int sqlite3VdbeList(
   if( p->rc==SQLITE_NOMEM ){
     /* This happens if a malloc() inside a call to sqlite3_column_text() or
     ** sqlite3_column_text16() failed.  */
-    db->mallocFailed = 1;
+    sqlite3OomFault(db);
     return SQLITE_ERROR;
   }
 
@@ -2711,12 +2709,12 @@ int sqlite3VdbeTransferError(Vdbe *p){
   sqlite3 *db = p->db;
   int rc = p->rc;
   if( p->zErrMsg ){
-    u8 mallocFailed = db->mallocFailed;
+    db->bBenignMalloc++;
     sqlite3BeginBenignMalloc();
     if( db->pErr==0 ) db->pErr = sqlite3ValueNew(db);
     sqlite3ValueSetStr(db->pErr, -1, p->zErrMsg, SQLITE_UTF8, SQLITE_TRANSIENT);
     sqlite3EndBenignMalloc();
-    db->mallocFailed = mallocFailed;
+    db->bBenignMalloc--;
     db->errCode = rc;
   }else{
     sqlite3Error(db, rc);
diff --git a/src/vdbemem.c b/src/vdbemem.c
index 0eeb59ef8..974b99074 100644
--- a/src/vdbemem.c
+++ b/src/vdbemem.c
@@ -1381,7 +1381,7 @@ static int valueFromExpr(
   return rc;
 
 no_mem:
-  db->mallocFailed = 1;
+  sqlite3OomFault(db);
   sqlite3DbFree(db, zVal);
   assert( *ppVal==0 );
 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
diff --git a/src/vtab.c b/src/vtab.c
index ea79cd8ce..ca444944f 100644
--- a/src/vtab.c
+++ b/src/vtab.c
@@ -62,7 +62,7 @@ static int createModule(
       pDel = (Module *)sqlite3HashInsert(&db->aModule,zCopy,(void*)pMod);
       assert( pDel==0 || pDel==pMod );
       if( pDel ){
-        db->mallocFailed = 1;
+        sqlite3OomFault(db);
         sqlite3DbFree(db, pDel);
       }
     }
@@ -439,7 +439,7 @@ void sqlite3VtabFinishParse(Parse *pParse, Token *pEnd){
     assert( sqlite3SchemaMutexHeld(db, 0, pSchema) );
     pOld = sqlite3HashInsert(&pSchema->tblHash, zName, pTab);
     if( pOld ){
-      db->mallocFailed = 1;
+      sqlite3OomFault(db);
       assert( pTab==pOld );  /* Malloc must have failed inside HashInsert() */
       return;
     }
@@ -530,7 +530,7 @@ static int vtabCallConstructor(
   db->pVtabCtx = &sCtx;
   rc = xConstruct(db, pMod->pAux, nArg, azArg, &pVTable->pVtab, &zErr);
   db->pVtabCtx = sCtx.pPrior;
-  if( rc==SQLITE_NOMEM ) db->mallocFailed = 1;
+  if( rc==SQLITE_NOMEM ) sqlite3OomFault(db);
   assert( sCtx.pTab==pTab );
 
   if( SQLITE_OK!=rc ){
@@ -1088,7 +1088,7 @@ void sqlite3VtabMakeWritable(Parse *pParse, Table *pTab){
     pToplevel->apVtabLock = apVtabLock;
     pToplevel->apVtabLock[pToplevel->nVtabLock++] = pTab;
   }else{
-    pToplevel->db->mallocFailed = 1;
+    sqlite3OomFault(pToplevel->db);
   }
 }
 
diff --git a/src/where.c b/src/where.c
index 8c8dfbb7b..d3a4ab87e 100644
--- a/src/where.c
+++ b/src/where.c
@@ -943,7 +943,7 @@ static int vtabBestIndex(Parse *pParse, Table *pTab, sqlite3_index_info *p){
 
   if( rc!=SQLITE_OK ){
     if( rc==SQLITE_NOMEM ){
-      pParse->db->mallocFailed = 1;
+      sqlite3OomFault(pParse->db);
     }else if( !pVtab->zErrMsg ){
       sqlite3ErrorMsg(pParse, "%s", sqlite3ErrStr(rc));
     }else{
diff --git a/src/whereexpr.c b/src/whereexpr.c
index e0b8bac1b..ec244bcb4 100644
--- a/src/whereexpr.c
+++ b/src/whereexpr.c
@@ -563,7 +563,6 @@ static void exprAnalyzeOrTerm(
         sqlite3WhereSplit(pAndWC, pOrTerm->pExpr, TK_AND);
         sqlite3WhereExprAnalyze(pSrc, pAndWC);
         pAndWC->pOuter = pWC;
-        testcase( db->mallocFailed );
         if( !db->mallocFailed ){
           for(j=0, pAndTerm=pAndWC->a; j<pAndWC->nTerm; j++, pAndTerm++){
             assert( pAndTerm->pExpr );