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Save a few cycles in EXPLAIN and related commands by not bothering to form

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a physical tuple in do_tup_output().  A virtual tuple is easier to set up
and also easier for most tuple receivers to process.  Per my comment on
Robert Haas' recent patch in this code.
This commit is contained in:
Tom Lane 2009-07-23 21:27:10 +00:00
parent 6a0865e4bb
commit adfa04293b
1 changed files with 13 additions and 12 deletions
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25
src/backend/executor/execTuples.c
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@ -15,7 +15,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/execTuples.c,v 1.108 2009/07/22 17:00:20 tgl Exp $
* $PostgreSQL: pgsql/src/backend/executor/execTuples.c,v 1.109 2009/07/23 21:27:10 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1215,27 +1215,28 @@ begin_tup_output_tupdesc(DestReceiver *dest, TupleDesc tupdesc)
/*
* write a single tuple
*
* XXX This could be made more efficient, since in reality we probably only
* need a virtual tuple.
*/
void
do_tup_output(TupOutputState *tstate, Datum *values, bool *isnull)
{
TupleDesc tupdesc = tstate->slot->tts_tupleDescriptor;
HeapTuple tuple;
TupleTableSlot *slot = tstate->slot;
int natts = slot->tts_tupleDescriptor->natts;
/* form a tuple */
tuple = heap_form_tuple(tupdesc, values, isnull);
/* make sure the slot is clear */
ExecClearTuple(slot);
/* put it in a slot */
ExecStoreTuple(tuple, tstate->slot, InvalidBuffer, true);
/* insert data */
memcpy(slot->tts_values, values, natts * sizeof(Datum));
memcpy(slot->tts_isnull, isnull, natts * sizeof(bool));
/* mark slot as containing a virtual tuple */
ExecStoreVirtualTuple(slot);
/* send the tuple to the receiver */
(*tstate->dest->receiveSlot) (tstate->slot, tstate->dest);
(*tstate->dest->receiveSlot) (slot, tstate->dest);
/* clean up */
ExecClearTuple(tstate->slot);
ExecClearTuple(slot);
}
/*