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Overview
| Comment: | Do not run ON UPDATE actions of a foreign key constraint unless at least one column value really does change. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
71ac8e28e55ff0250ebe2fe239159ce2 |
| User & Date: | drh 2009-09-23 03:01:59 |
Context
|
2009-09-23
| ||
| 08:43 | Add missing comments to fkey.c. Also, change the terminology used for comments and names in fkey.c from "referenced/referencing" to "parent/child". This is arguably less correct, but is easier to follow. (check-in: 540c2d18 user: dan tags: trunk) | |
| 03:01 | Do not run ON UPDATE actions of a foreign key constraint unless at least one column value really does change. (check-in: 71ac8e28 user: drh tags: trunk) | |
| 02:29 | Generalize the IS and IS NOT operators so that their right-hand side can be an arbitrary expression and not simple the constant NULL. They work like = and <> except that NULL values compare equal to one another an unequal to everything else. (check-in: 98853f61 user: drh tags: trunk) | |
Changes
Changes to src/fkey.c.
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}
static void fkTriggerDelete(sqlite3 *dbMem, Trigger *p){
if( p ){
TriggerStep *pStep = p->step_list;
sqlite3ExprDelete(dbMem, pStep->pWhere);
sqlite3ExprListDelete(dbMem, pStep->pExprList);
sqlite3DbFree(dbMem, p);
}
}
void sqlite3FkCheck(
Parse *pParse, /* Parse context */
Table *pTab, /* Row is being deleted from this table */
................................................................................
int nFrom; /* Length in bytes of zFrom */
Index *pIdx = 0; /* Parent key index for this FK */
int *aiCol = 0; /* child table cols -> parent key cols */
TriggerStep *pStep; /* First (only) step of trigger program */
Expr *pWhere = 0; /* WHERE clause of trigger step */
ExprList *pList = 0; /* Changes list if ON UPDATE CASCADE */
int i; /* Iterator variable */
if( locateFkeyIndex(pParse, pTab, pFKey, &pIdx, &aiCol) ) return 0;
assert( aiCol || pFKey->nCol==1 );
for(i=0; i<pFKey->nCol; i++){
Token tOld = { "old", 3 }; /* Literal "old" token */
Token tNew = { "new", 3 }; /* Literal "new" token */
................................................................................
sqlite3PExpr(pParse, TK_DOT,
sqlite3PExpr(pParse, TK_ID, 0, 0, &tOld),
sqlite3PExpr(pParse, TK_ID, 0, 0, &tToCol)
, 0)
, 0);
pWhere = sqlite3ExprAnd(db, pWhere, pEq);
if( action!=OE_Cascade || pChanges ){
Expr *pNew;
if( action==OE_Cascade ){
pNew = sqlite3PExpr(pParse, TK_DOT,
sqlite3PExpr(pParse, TK_ID, 0, 0, &tNew),
sqlite3PExpr(pParse, TK_ID, 0, 0, &tToCol)
, 0);
................................................................................
pStep = pTrigger->step_list = (TriggerStep *)&pTrigger[1];
pStep->target.z = (char *)&pStep[1];
pStep->target.n = nFrom;
memcpy((char *)pStep->target.z, zFrom, nFrom);
pStep->pWhere = sqlite3ExprDup(db, pWhere, EXPRDUP_REDUCE);
pStep->pExprList = sqlite3ExprListDup(db, pList, EXPRDUP_REDUCE);
}
/* Re-enable the lookaside buffer, if it was disabled earlier. */
db->lookaside.bEnabled = enableLookaside;
sqlite3ExprDelete(pParse->db, pWhere);
sqlite3ExprListDelete(pParse->db, pList);
if( db->mallocFailed==1 ){
fkTriggerDelete(db, pTrigger);
return 0;
}
pStep->op = (action!=OE_Cascade || pChanges) ? TK_UPDATE : TK_DELETE;
pStep->pTrig = pTrigger;
|
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}
static void fkTriggerDelete(sqlite3 *dbMem, Trigger *p){
if( p ){
TriggerStep *pStep = p->step_list;
sqlite3ExprDelete(dbMem, pStep->pWhere);
sqlite3ExprListDelete(dbMem, pStep->pExprList);
sqlite3ExprDelete(dbMem, p->pWhen);
sqlite3DbFree(dbMem, p);
}
}
void sqlite3FkCheck(
Parse *pParse, /* Parse context */
Table *pTab, /* Row is being deleted from this table */
................................................................................
int nFrom; /* Length in bytes of zFrom */
Index *pIdx = 0; /* Parent key index for this FK */
int *aiCol = 0; /* child table cols -> parent key cols */
TriggerStep *pStep; /* First (only) step of trigger program */
Expr *pWhere = 0; /* WHERE clause of trigger step */
ExprList *pList = 0; /* Changes list if ON UPDATE CASCADE */
int i; /* Iterator variable */
Expr *pWhen = 0; /* WHEN clause for the trigger */
if( locateFkeyIndex(pParse, pTab, pFKey, &pIdx, &aiCol) ) return 0;
assert( aiCol || pFKey->nCol==1 );
for(i=0; i<pFKey->nCol; i++){
Token tOld = { "old", 3 }; /* Literal "old" token */
Token tNew = { "new", 3 }; /* Literal "new" token */
................................................................................
sqlite3PExpr(pParse, TK_DOT,
sqlite3PExpr(pParse, TK_ID, 0, 0, &tOld),
sqlite3PExpr(pParse, TK_ID, 0, 0, &tToCol)
, 0)
, 0);
pWhere = sqlite3ExprAnd(db, pWhere, pEq);
/* For ON UPDATE, construct the next term of the WHEN clause.
** The final WHEN clause will be like this:
**
** WHEN NOT(old.col1 IS new.col1 AND ... AND old.colN IS new.colN)
*/
if( pChanges ){
pEq = sqlite3PExpr(pParse, TK_IS,
sqlite3PExpr(pParse, TK_DOT,
sqlite3PExpr(pParse, TK_ID, 0, 0, &tOld),
sqlite3PExpr(pParse, TK_ID, 0, 0, &tToCol),
0),
sqlite3PExpr(pParse, TK_DOT,
sqlite3PExpr(pParse, TK_ID, 0, 0, &tNew),
sqlite3PExpr(pParse, TK_ID, 0, 0, &tToCol),
0),
0);
pWhen = sqlite3ExprAnd(db, pWhen, pEq);
}
if( action!=OE_Cascade || pChanges ){
Expr *pNew;
if( action==OE_Cascade ){
pNew = sqlite3PExpr(pParse, TK_DOT,
sqlite3PExpr(pParse, TK_ID, 0, 0, &tNew),
sqlite3PExpr(pParse, TK_ID, 0, 0, &tToCol)
, 0);
................................................................................
pStep = pTrigger->step_list = (TriggerStep *)&pTrigger[1];
pStep->target.z = (char *)&pStep[1];
pStep->target.n = nFrom;
memcpy((char *)pStep->target.z, zFrom, nFrom);
pStep->pWhere = sqlite3ExprDup(db, pWhere, EXPRDUP_REDUCE);
pStep->pExprList = sqlite3ExprListDup(db, pList, EXPRDUP_REDUCE);
if( pWhen ){
pWhen = sqlite3PExpr(pParse, TK_NOT, pWhen, 0, 0);
pTrigger->pWhen = sqlite3ExprDup(db, pWhen, EXPRDUP_REDUCE);
}
}
/* Re-enable the lookaside buffer, if it was disabled earlier. */
db->lookaside.bEnabled = enableLookaside;
sqlite3ExprDelete(db, pWhere);
sqlite3ExprDelete(db, pWhen);
sqlite3ExprListDelete(db, pList);
if( db->mallocFailed==1 ){
fkTriggerDelete(db, pTrigger);
return 0;
}
pStep->op = (action!=OE_Cascade || pChanges) ? TK_UPDATE : TK_DELETE;
pStep->pTrig = pTrigger;
|