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Overview
Comment:Fix some comments in fkey.c. Add tests to fkey8.test.
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SHA1:210cb2a6aaf780365064a26c0c99926bd6346e19
User & Date: dan 2014-12-17 14:38:45
Context
2014-12-17
15:03
Experimental opimizations to speed up FK constraint CASCADE and SET NULL action processing. check-in: 8c5dd6cc user: dan tags: trunk
14:38
Fix some comments in fkey.c. Add tests to fkey8.test. Closed-Leaf check-in: 210cb2a6 user: dan tags: experimental-fk-actions
2014-12-16
20:13
Experimental opimizations to speed up FK constraint CASCADE and SET NULL action processing. Requires further testing. check-in: 35a20a5f user: dan tags: experimental-fk-actions
Changes
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Changes to src/fkey.c.

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  /* Resolve the references in the WHERE clause. */
  memset(&sNameContext, 0, sizeof(NameContext));
  sNameContext.pSrcList = pSrc;
  sNameContext.pParse = pParse;
  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
  ** each row found. Otherwise, for deferred constraints, increment the
  ** deferred constraint counter by nIncr for each row selected.  */
  pWInfo = sqlite3WhereBegin(pParse, pSrc, pWhere, 0, 0, 0, 0);
  sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, nIncr);
  if( pWInfo ){
    sqlite3WhereEnd(pWInfo);
  }

  /* Clean up the WHERE clause constructed above. */
................................................................................
    }
    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. 
      **
      ** 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 the child keys
      ** 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);
  }

  /* Loop through all the foreign key constraints that refer to this table.
................................................................................
      if( regNew!=0 ){
        fkScanChildren(pParse, pSrc, pTab, pIdx, pFKey, aiCol, regNew, -1);
      }
      if( regOld!=0 ){
        int eAction = pFKey->aAction[aChange!=0];
        fkScanChildren(pParse, pSrc, pTab, pIdx, pFKey, aiCol, regOld, 1);
        /* If this is a deferred FK constraint, or a CASCADE or SET NULL
        ** action applies, do not set the may-abort flag on this statement.
        ** The flag may be set on this statement for some other reason, but
        ** not as a result of this FK constraint. */













        if( !pFKey->isDeferred && eAction!=OE_Cascade && eAction!=OE_SetNull ){
          sqlite3MayAbort(pParse);
        }
      }
      pItem->zName = 0;
      sqlite3SrcListDelete(db, pSrc);
    }







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  /* Resolve the references in the WHERE clause. */
  memset(&sNameContext, 0, sizeof(NameContext));
  sNameContext.pSrcList = pSrc;
  sNameContext.pParse = pParse;
  sqlite3ResolveExprNames(&sNameContext, pWhere);

  /* Create VDBE to loop through the entries in pSrc that match the WHERE
  ** clause. For each row found, increment either the deferred or immediate
  ** foreign key constraint counter. */

  pWInfo = sqlite3WhereBegin(pParse, pSrc, pWhere, 0, 0, 0, 0);
  sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, nIncr);
  if( pWInfo ){
    sqlite3WhereEnd(pWInfo);
  }

  /* Clean up the WHERE clause constructed above. */
................................................................................
    }
    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. 
      **
      ** 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);
  }

  /* Loop through all the foreign key constraints that refer to this table.
................................................................................
      if( regNew!=0 ){
        fkScanChildren(pParse, pSrc, pTab, pIdx, pFKey, aiCol, regNew, -1);
      }
      if( regOld!=0 ){
        int eAction = pFKey->aAction[aChange!=0];
        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);
    }

Changes to test/fkey8.test.

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    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);
  }























} {
  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








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    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