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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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src/backend/optimizer/plan
- subselect.c

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+15

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`‎src/backend/optimizer/plan/subselect.c`

Lines changed: 15 additions & 24 deletions

Original file line number	Diff line number	Diff line change
`@@ -7,7 +7,7 @@`
`7`	`7`	`* Portions Copyright (c) 1994, Regents of the University of California`
`8`	`8`	`*`
`9`	`9`	`* 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 $`
`11`	`11`	`*`
`12`	`12`	`*-------------------------------------------------------------------------`
`13`	`13`	`*/`
`@@ -302,8 +302,8 @@ make_subplan(SubLink *slink)`
`302`	`302`	`* the top of an uncorrelated/undirect correlated subplan, which lets`
`303`	`303`	`* us do the work of evaluating the subplan only once. We do this`
`304`	`304`	`* 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.`
`307`	`307`	`*/`
`308`	`308`	`if (node->parParam==NIL)`
`309`	`309`	`{`
`@@ -312,28 +312,19 @@ make_subplan(SubLink *slink)`
`312`	`312`	`switch (nodeTag(plan))`
`313`	`313`	`{`
`314`	`314`	`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`		`-Listindxqual= ((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`	`+}`
`335`	`327`	`break;`
`336`		`-}`
`337`	`328`	`caseT_Material:`
`338`	`329`	`caseT_Sort:`
`339`	`330`	`/* Don't add another Material node if there's one already,`

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`‎src/backend/optimizer/plan/subselect.c`

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