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Add a WHEN clause to CREATE TRIGGER, allowing a boolean expression to be

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checked to determine whether the trigger should be fired.

For BEFORE triggers this is mostly a matter of spec compliance; but for AFTER
triggers it can provide a noticeable performance improvement, since queuing of
a deferred trigger event and re-fetching of the row(s) at end of statement can
be short-circuited if the trigger does not need to be fired.

Takahiro Itagaki, reviewed by KaiGai Kohei.
This commit is contained in:
Tom Lane
2009-11-20 20:38:12 +00:00
parent 201a45c4fa
commit 7fc0f06221
27 changed files with 783 additions and 100 deletions
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13
src/backend/commands/tablecmds.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.305 2009/11/04 12:24:23 heikki Exp $
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.306 2009/11/20 20:38:10 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -5403,7 +5403,7 @@ validateForeignKeyConstraint(Constraint *fkconstraint,
trig.tgconstraint = constraintOid;
trig.tgdeferrable = FALSE;
trig.tginitdeferred = FALSE;
/* we needn't fill in tgargs */
/* we needn't fill in tgargs or tgqual */
/*
* See if we can do it with a single LEFT JOIN query. A FALSE result
@ -5476,13 +5476,14 @@ CreateFKCheckTrigger(RangeVar *myRel, Constraint *fkconstraint,
}
fk_trigger->columns = NIL;
fk_trigger->whenClause = NULL;
fk_trigger->isconstraint = true;
fk_trigger->deferrable = fkconstraint->deferrable;
fk_trigger->initdeferred = fkconstraint->initdeferred;
fk_trigger->constrrel = fkconstraint->pktable;
fk_trigger->args = NIL;
(void) CreateTrigger(fk_trigger, constraintOid, indexOid,
(void) CreateTrigger(fk_trigger, NULL, constraintOid, indexOid,
"RI_ConstraintTrigger", false);
/* Make changes-so-far visible */
@ -5527,6 +5528,7 @@ createForeignKeyTriggers(Relation rel, Constraint *fkconstraint,
fk_trigger->row = true;
fk_trigger->events = TRIGGER_TYPE_DELETE;
fk_trigger->columns = NIL;
fk_trigger->whenClause = NULL;
fk_trigger->isconstraint = true;
fk_trigger->constrrel = myRel;
switch (fkconstraint->fk_del_action)
@ -5563,7 +5565,7 @@ createForeignKeyTriggers(Relation rel, Constraint *fkconstraint,
}
fk_trigger->args = NIL;
(void) CreateTrigger(fk_trigger, constraintOid, indexOid,
(void) CreateTrigger(fk_trigger, NULL, constraintOid, indexOid,
"RI_ConstraintTrigger", false);
/* Make changes-so-far visible */
@ -5580,6 +5582,7 @@ createForeignKeyTriggers(Relation rel, Constraint *fkconstraint,
fk_trigger->row = true;
fk_trigger->events = TRIGGER_TYPE_UPDATE;
fk_trigger->columns = NIL;
fk_trigger->whenClause = NULL;
fk_trigger->isconstraint = true;
fk_trigger->constrrel = myRel;
switch (fkconstraint->fk_upd_action)
@ -5616,7 +5619,7 @@ createForeignKeyTriggers(Relation rel, Constraint *fkconstraint,
}
fk_trigger->args = NIL;
(void) CreateTrigger(fk_trigger, constraintOid, indexOid,
(void) CreateTrigger(fk_trigger, NULL, constraintOid, indexOid,
"RI_ConstraintTrigger", false);
}