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Commite8be8ff

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Further tweaking of logic that decides when to materialize an uncorrelated
subplan: do it if subplan has subplans itself, and always do it if thesubplan is an indexscan. (I originally set it to materialize an indexscanonly if the indexqual is fairly selective, but I dunno what I wasthinking ... an unselective indexscan is still expensive ...)
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1 file changed

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‎src/backend/optimizer/plan/subselect.c

Lines changed: 15 additions & 24 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
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* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.29 2000/03/02 04:08:16 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.30 2000/03/11 23:53:41 tgl Exp $
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*
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*-------------------------------------------------------------------------
1313
*/
@@ -302,8 +302,8 @@ make_subplan(SubLink *slink)
302302
* the top of an uncorrelated/undirect correlated subplan, which lets
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* us do the work of evaluating the subplan only once. We do this
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* if the subplan's top plan node is anything more complicated than
305-
* a sequentialor indexscan, and we do it even forthose plan types
306-
*if thequal appears selective enough to eliminate many tuples.
305+
* aplainsequential scan, and we do it even forseqscan if the
306+
* qual appears selective enough to eliminate many tuples.
307307
*/
308308
if (node->parParam==NIL)
309309
{
@@ -312,28 +312,19 @@ make_subplan(SubLink *slink)
312312
switch (nodeTag(plan))
313313
{
314314
caseT_SeqScan:
315-
{
316-
Selectivityqualsel;
317-
318-
qualsel=clauselist_selectivity(subquery,plan->qual,0);
319-
/* Is 10% selectivity a good threshold?? */
320-
use_material=qualsel<0.10;
321-
break;
322-
}
323-
caseT_IndexScan:
324-
{
325-
List*indxqual= ((IndexScan*)plan)->indxqualorig;
326-
Selectivityqualsel;
327-
328-
qualsel=clauselist_selectivity(subquery,plan->qual,0);
329-
qualsel *=clauselist_selectivity(subquery,indxqual,0);
330-
/* Note: if index is lossy, we just double-counted the
331-
* index selectivity. Worth fixing?
332-
*/
333-
/* Is 10% selectivity a good threshold?? */
334-
use_material=qualsel<0.10;
315+
if (plan->initPlan||plan->subPlan)
316+
use_material= true;
317+
else
318+
{
319+
Selectivityqualsel;
320+
321+
qualsel=clauselist_selectivity(subquery,
322+
plan->qual,
323+
0);
324+
/* Is 10% selectivity a good threshold?? */
325+
use_material=qualsel<0.10;
326+
}
335327
break;
336-
}
337328
caseT_Material:
338329
caseT_Sort:
339330
/* Don't add another Material node if there's one already,

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