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

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

View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/nodeModifyTable.c,v 1.2 2009/10/26 02:26:31 tgl Exp $
* $PostgreSQL: pgsql/src/backend/executor/nodeModifyTable.c,v 1.3 2009/11/20 20:38:10 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -215,9 +215,10 @@ ExecInsert(TupleTableSlot *slot,
* slot should not try to clear it.
*/
TupleTableSlot *newslot = estate->es_trig_tuple_slot;
TupleDesc tupdesc = RelationGetDescr(resultRelationDesc);
if (newslot->tts_tupleDescriptor != slot->tts_tupleDescriptor)
ExecSetSlotDescriptor(newslot, slot->tts_tupleDescriptor);
if (newslot->tts_tupleDescriptor != tupdesc)
ExecSetSlotDescriptor(newslot, tupdesc);
ExecStoreTuple(newtuple, newslot, InvalidBuffer, false);
slot = newslot;
tuple = newtuple;
@ -467,9 +468,10 @@ ExecUpdate(ItemPointer tupleid,
* slot should not try to clear it.
*/
TupleTableSlot *newslot = estate->es_trig_tuple_slot;
TupleDesc tupdesc = RelationGetDescr(resultRelationDesc);
if (newslot->tts_tupleDescriptor != slot->tts_tupleDescriptor)
ExecSetSlotDescriptor(newslot, slot->tts_tupleDescriptor);
if (newslot->tts_tupleDescriptor != tupdesc)
ExecSetSlotDescriptor(newslot, tupdesc);
ExecStoreTuple(newtuple, newslot, InvalidBuffer, false);
slot = newslot;
tuple = newtuple;