Experimental opimizations to speed up FK constraint CASCADE and SET NULL action processing.

FossilOrigin-Name: 8c5dd6cc259e0cdaaddaa52ccfa96fee6b166906

manifest

@@ -1,5 +1,5 @@
-C Fix\sthe\se_walauto.test\sscript\sso\sthat\sit\sworks\son\swindows.
+C Experimental\sopimizations\sto\sspeed\sup\sFK\sconstraint\sCASCADE\sand\sSET\sNULL\saction\sprocessing.
-D 2014-12-16T12:46:38.635
+D 2014-12-17T15:03:50.611
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 6c4f961fa91d0b4fa121946a19f9e5eac2f2f809
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -184,7 +184,7 @@ F src/date.c 93594514aae68de117ca4a2a0d6cc63eddf26744
 F src/delete.c 0750b1eb4d96cd3fb2c798599a3a7c85e92f1417
 F src/expr.c 00da3072f362b06f39ce4052baa1d4ce2bb36d1c
 F src/fault.c 160a0c015b6c2629d3899ed2daf63d75754a32bb
-F src/fkey.c da985ae673efef2c712caef825a5d2edb087ead7
+F src/fkey.c e0444b61bed271a76840cbe6182df93a9baa3f12
 F src/func.c 6d3c4ebd72aa7923ce9b110a7dc15f9b8c548430
 F src/global.c 6ded36dda9466fc1c9a3c5492ded81d79bf3977d
 F src/hash.c 4263fbc955f26c2e8cdc0cf214bc42435aa4e4f5
@@ -295,7 +295,7 @@ F src/vdbe.c 1a9e671c9cfc259e4d2affc71f7df4a4c00a842c
 F src/vdbe.h 6fc69d9c5e146302c56e163cb4b31d1ee64a18c3
 F src/vdbeInt.h 9bb69ff2447c34b6ccc58b34ec35b615f86ead78
 F src/vdbeapi.c 4bc511a46b9839392ae0e90844a71dc96d9dbd71
-F src/vdbeaux.c 6f7f39c3fcf0f5923758df8561bb5d843908a553
+F src/vdbeaux.c 07ef87c6d4b5abdf13ff33babb10205702fdab0a
 F src/vdbeblob.c 4af4bfb71f6df7778397b4a0ebc1879793276778
 F src/vdbemem.c 31d8eabb0cd78bfeab4e5124c7363c3e9e54db9f
 F src/vdbesort.c c150803a3e98fbc68bd07772cbbd4328a0a7212d
@@ -504,6 +504,7 @@ F test/fkey4.test 86446017011273aad8f9a99c1a65019e7bd9ca9d
 F test/fkey5.test 8a1fde4e7721ae00b05b3178888833726ca2df8d
 F test/fkey6.test abb59f866c1b44926fd02d1fdd217d831fe04f48
 F test/fkey7.test 72e915890ee4a005daaf3002cb208e8fe973ac13
+F test/fkey8.test 8f08203458321e6c19a263829de4cfc936274ab0
 F test/fkey_malloc.test 594a7ea1fbab553c036c70813cd8bd9407d63749
 F test/format4.test 1f0cac8ff3895e9359ed87e41aaabee982a812eb
 F test/fts-9fd058691.test 78b887e30ae6816df0e1fed6259de4b5a64ad33c
@@ -1232,7 +1233,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P ae43539e62e76676a3daf561b629a1b9b4e2d2c9
+P 7d092ebb6724c3c0fdc05dc94ca767d158933fb5 210cb2a6aaf780365064a26c0c99926bd6346e19
-R 6cb5309eecfa4835aff26790e68b0f80
+R 2edc2fe620223f33e078e9395972a943
-U drh
+U dan
-Z 6fc407d3934d070a5bb755e43a0ba0ad
+Z c2959ecd9d3a1afd4baaa55723226ea7

manifest.uuid

@@ -1 +1 @@
-7d092ebb6724c3c0fdc05dc94ca767d158933fb5
+8c5dd6cc259e0cdaaddaa52ccfa96fee6b166906

src/fkey.c

@@ -437,7 +437,7 @@ static void fkLookupParent(
         OE_Abort, 0, P4_STATIC, P5_ConstraintFK);
   }else{
     if( nIncr>0 && pFKey->isDeferred==0 ){
-      sqlite3ParseToplevel(pParse)->mayAbort = 1;
+      sqlite3MayAbort(pParse);
     }
     sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, nIncr);
   }
@@ -509,6 +509,10 @@ static Expr *exprTableColumn(
 ** code for an SQL UPDATE operation, this function may be called twice -
 ** once to "delete" the old row and once to "insert" the new row.
 **
+** Parameter nIncr is passed -1 when inserting a row (as this may decrease
+** the number of FK violations in the db) or +1 when deleting one (as this
+** may increase the number of FK constraint problems).
+**
 ** The code generated by this function scans through the rows in the child
 ** table that correspond to the parent table row being deleted or inserted.
 ** For each child row found, one of the following actions is taken:
@@ -625,13 +629,9 @@ static void fkScanChildren(
   sqlite3ResolveExprNames(&sNameContext, pWhere);
 
   /* Create VDBE to loop through the entries in pSrc that match the WHERE
-  ** clause. If the constraint is not deferred, throw an exception for
+  ** clause. For each row found, increment either the deferred or immediate
-  ** each row found. Otherwise, for deferred constraints, increment the
+  ** foreign key constraint counter. */
-  ** deferred constraint counter by nIncr for each row selected.  */
   pWInfo = sqlite3WhereBegin(pParse, pSrc, pWhere, 0, 0, 0, 0);
-  if( nIncr>0 && pFKey->isDeferred==0 ){
-    sqlite3ParseToplevel(pParse)->mayAbort = 1;
-  }
   sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, nIncr);
   if( pWInfo ){
     sqlite3WhereEnd(pWInfo);
@@ -810,6 +810,24 @@ static int fkParentIsModified(
   return 0;
 }
 
+/*
+** Return true if the parser passed as the first argument is being
+** used to code a trigger that is really a "SET NULL" action belonging
+** to trigger pFKey.
+*/
+static int isSetNullAction(Parse *pParse, FKey *pFKey){
+  Parse *pTop = sqlite3ParseToplevel(pParse);
+  if( pTop->pTriggerPrg ){
+    Trigger *p = pTop->pTriggerPrg->pTrigger;
+    if( (p==pFKey->apTrigger[0] && pFKey->aAction[0]==OE_SetNull)
+     || (p==pFKey->apTrigger[1] && pFKey->aAction[1]==OE_SetNull)
+    ){
+      return 1;
+    }
+  }
+  return 0;
+}
+
 /*
 ** This function is called when inserting, deleting or updating a row of
 ** table pTab to generate VDBE code to perform foreign key constraint 
@@ -862,7 +880,7 @@ void sqlite3FkCheck(
     int *aiCol;
     int iCol;
     int i;
-    int isIgnore = 0;
+    int bIgnore = 0;
 
     if( aChange 
      && sqlite3_stricmp(pTab->zName, pFKey->zTo)!=0
@@ -921,7 +939,7 @@ void sqlite3FkCheck(
         int rcauth;
         char *zCol = pTo->aCol[pIdx ? pIdx->aiColumn[i] : pTo->iPKey].zName;
         rcauth = sqlite3AuthReadCol(pParse, pTo->zName, zCol, iDb);
-        isIgnore = (rcauth==SQLITE_IGNORE);
+        bIgnore = (rcauth==SQLITE_IGNORE);
       }
 #endif
     }
@@ -936,12 +954,18 @@ void sqlite3FkCheck(
       /* A row is being removed from the child table. Search for the parent.
       ** If the parent does not exist, removing the child row resolves an 
       ** outstanding foreign key constraint violation. */
-      fkLookupParent(pParse, iDb, pTo, pIdx, pFKey, aiCol, regOld, -1,isIgnore);
+      fkLookupParent(pParse, iDb, pTo, pIdx, pFKey, aiCol, regOld, -1, bIgnore);
     }
-    if( regNew!=0 ){
+    if( regNew!=0 && !isSetNullAction(pParse, pFKey) ){
       /* A row is being added to the child table. If a parent row cannot
-      ** be found, adding the child row has violated the FK constraint. */ 
+      ** be found, adding the child row has violated the FK constraint. 
-      fkLookupParent(pParse, iDb, pTo, pIdx, pFKey, aiCol, regNew, +1,isIgnore);
+      **
+      ** If this operation is being performed as part of a trigger program
+      ** that is actually a "SET NULL" action belonging to this very 
+      ** foreign key, then omit this scan altogether. As all child key
+      ** values are guaranteed to be NULL, it is not possible for adding
+      ** this row to cause an FK violation.  */
+      fkLookupParent(pParse, iDb, pTo, pIdx, pFKey, aiCol, regNew, +1, bIgnore);
     }
 
     sqlite3DbFree(db, aiFree);
@@ -962,8 +986,8 @@ void sqlite3FkCheck(
      && !pParse->pToplevel && !pParse->isMultiWrite 
     ){
       assert( regOld==0 && regNew!=0 );
-      /* Inserting a single row into a parent table cannot cause an immediate
+      /* Inserting a single row into a parent table cannot cause (or fix)
-      ** foreign key violation. So do nothing in this case.  */
+      ** an immediate foreign key violation. So do nothing in this case.  */
       continue;
     }
 
@@ -987,13 +1011,28 @@ void sqlite3FkCheck(
         fkScanChildren(pParse, pSrc, pTab, pIdx, pFKey, aiCol, regNew, -1);
       }
       if( regOld!=0 ){
-        /* If there is a RESTRICT action configured for the current operation
+        int eAction = pFKey->aAction[aChange!=0];
-        ** on the parent table of this FK, then throw an exception 
-        ** immediately if the FK constraint is violated, even if this is a
-        ** deferred trigger. That's what RESTRICT means. To defer checking
-        ** the constraint, the FK should specify NO ACTION (represented
-        ** using OE_None). NO ACTION is the default.  */
         fkScanChildren(pParse, pSrc, pTab, pIdx, pFKey, aiCol, regOld, 1);
+        /* If this is a deferred FK constraint, or a CASCADE or SET NULL
+        ** action applies, then any foreign key violations caused by
+        ** removing the parent key will be rectified by the action trigger.
+        ** So do not set the "may-abort" flag in this case.
+        **
+        ** Note 1: If the FK is declared "ON UPDATE CASCADE", then the
+        ** may-abort flag will eventually be set on this statement anyway
+        ** (when this function is called as part of processing the UPDATE
+        ** within the action trigger).
+        **
+        ** Note 2: At first glance it may seem like SQLite could simply omit
+        ** all OP_FkCounter related scans when either CASCADE or SET NULL
+        ** applies. The trouble starts if the CASCADE or SET NULL action 
+        ** trigger causes other triggers or action rules attached to the 
+        ** child table to fire. In these cases the fk constraint counters
+        ** might be set incorrectly if any OP_FkCounter related scans are 
+        ** omitted.  */
+        if( !pFKey->isDeferred && eAction!=OE_Cascade && eAction!=OE_SetNull ){
+          sqlite3MayAbort(pParse);
+        }
       }
       pItem->zName = 0;
       sqlite3SrcListDelete(db, pSrc);

src/vdbeaux.c

@@ -396,6 +396,7 @@ static Op *opIterNext(VdbeOpIter *p){
 */
 int sqlite3VdbeAssertMayAbort(Vdbe *v, int mayAbort){
   int hasAbort = 0;
+  int hasFkCounter = 0;
   Op *pOp;
   VdbeOpIter sIter;
   memset(&sIter, 0, sizeof(sIter));
@@ -404,15 +405,17 @@ int sqlite3VdbeAssertMayAbort(Vdbe *v, int mayAbort){
   while( (pOp = opIterNext(&sIter))!=0 ){
     int opcode = pOp->opcode;
     if( opcode==OP_Destroy || opcode==OP_VUpdate || opcode==OP_VRename 
-#ifndef SQLITE_OMIT_FOREIGN_KEY
-     || (opcode==OP_FkCounter && pOp->p1==0 && pOp->p2==1) 
-#endif
      || ((opcode==OP_Halt || opcode==OP_HaltIfNull) 
       && ((pOp->p1&0xff)==SQLITE_CONSTRAINT && pOp->p2==OE_Abort))
     ){
       hasAbort = 1;
       break;
     }
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+    if( opcode==OP_FkCounter && pOp->p1==0 && pOp->p2==1 ){
+      hasFkCounter = 1;
+    }
+#endif
   }
   sqlite3DbFree(v->db, sIter.apSub);
 
@@ -421,7 +424,7 @@ int sqlite3VdbeAssertMayAbort(Vdbe *v, int mayAbort){
   ** through all opcodes and hasAbort may be set incorrectly. Return
   ** true for this case to prevent the assert() in the callers frame
   ** from failing.  */
-  return ( v->db->mallocFailed || hasAbort==mayAbort );
+  return ( v->db->mallocFailed || hasAbort==mayAbort || hasFkCounter );
 }
 #endif /* SQLITE_DEBUG - the sqlite3AssertMayAbort() function */
 

test/fkey8.test

@@ -0,0 +1,106 @@
+# 2001 September 15
+#
+# 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 implements regression tests for SQLite library.
+#
+# This file implements tests for foreign keys.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+set testprefix fkey8
+
+ifcapable {!foreignkey} {
+  finish_test
+  return
+}
+do_execsql_test 1.0 { PRAGMA foreign_keys = 1; }
+
+
+foreach {tn use_stmt sql schema} {
+  1   1 "DELETE FROM p1" {
+    CREATE TABLE p1(a PRIMARY KEY);
+    CREATE TABLE c1(b REFERENCES p1);
+  }
+
+  2.1     0 "DELETE FROM p1" {
+    CREATE TABLE p1(a PRIMARY KEY);
+    CREATE TABLE c1(b REFERENCES p1 ON DELETE CASCADE);
+  }
+  2.2   0 "DELETE FROM p1" {
+    CREATE TABLE p1(a PRIMARY KEY);
+    CREATE TABLE c1(b REFERENCES p1 ON DELETE SET NULL);
+  }
+  2.3   1 "DELETE FROM p1" {
+    CREATE TABLE p1(a PRIMARY KEY);
+    CREATE TABLE c1(b REFERENCES p1 ON DELETE SET DEFAULT);
+  }
+
+  3   1 "DELETE FROM p1" {
+    CREATE TABLE p1(a PRIMARY KEY);
+    CREATE TABLE c1(b REFERENCES p1 ON DELETE CASCADE);
+    CREATE TRIGGER ct1 AFTER DELETE ON c1 BEGIN
+      INSERT INTO p1 VALUES('x');
+    END;
+  }
+
+  4   1 "DELETE FROM p1" {
+    CREATE TABLE p1(a PRIMARY KEY);
+    CREATE TABLE c1(b REFERENCES p1 ON DELETE CASCADE, c PRIMARY KEY);
+    CREATE TABLE cc1(d REFERENCES c1);
+  }
+
+  5.1   0 "DELETE FROM p1" {
+    CREATE TABLE p1(a PRIMARY KEY);
+    CREATE TABLE c1(b REFERENCES p1 ON DELETE CASCADE, c PRIMARY KEY);
+    CREATE TABLE cc1(d REFERENCES c1 ON DELETE CASCADE);
+  }
+  5.2   0 "DELETE FROM p1" {
+    CREATE TABLE p1(a PRIMARY KEY);
+    CREATE TABLE c1(b REFERENCES p1 ON DELETE CASCADE, c PRIMARY KEY);
+    CREATE TABLE cc1(d REFERENCES c1 ON DELETE SET NULL);
+  }
+  5.3   1 "DELETE FROM p1" {
+    CREATE TABLE p1(a PRIMARY KEY);
+    CREATE TABLE c1(b REFERENCES p1 ON DELETE CASCADE, c PRIMARY KEY);
+    CREATE TABLE cc1(d REFERENCES c1 ON DELETE SET DEFAULT);
+  }
+
+  6.1   1 "UPDATE p1 SET a = ?" {
+    CREATE TABLE p1(a PRIMARY KEY);
+    CREATE TABLE c1(b REFERENCES p1 ON UPDATE SET NULL, c);
+  }
+  6.2   0 "UPDATE OR IGNORE p1 SET a = ?" {
+    CREATE TABLE p1(a PRIMARY KEY);
+    CREATE TABLE c1(b REFERENCES p1 ON UPDATE SET NULL, c);
+  }
+  6.3   1 "UPDATE OR IGNORE p1 SET a = ?" {
+    CREATE TABLE p1(a PRIMARY KEY);
+    CREATE TABLE c1(b REFERENCES p1 ON UPDATE CASCADE, c);
+  }
+  6.4   1 "UPDATE OR IGNORE p1 SET a = ?" {
+    CREATE TABLE p1(a PRIMARY KEY);
+    CREATE TABLE c1(b NOT NULL REFERENCES p1 ON UPDATE SET NULL, c);
+  }
+
+} {
+  drop_all_tables
+  do_test 1.$tn {
+    execsql $schema
+    set stmt [sqlite3_prepare_v2 db $sql -1 dummy]
+    set ret [uses_stmt_journal $stmt]
+    sqlite3_finalize $stmt
+    set ret
+  } $use_stmt
+}
+
+
+finish_test
+