Commit46a0eee

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Tweak nodeBitmapAnd to stop evaluating sub-plan scans if it finds it's

got an empty bitmap after any step; the remaining subplans can no longeraffect the result. Per a suggestion from Ilia Kantor.

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+30

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lines changed

+30

-4

lines changed

Lines changed: 11 additions & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@`
`8`	`8`	`*`
`9`	`9`	`*`
`10`	`10`	`* IDENTIFICATION`
`11`		`- * $PostgreSQL: pgsql/src/backend/executor/nodeBitmapAnd.c,v 1.2 2005/04/20 15:48:36 tgl Exp $`
	`11`	`+ * $PostgreSQL: pgsql/src/backend/executor/nodeBitmapAnd.c,v 1.3 2005/08/28 22:47:20 tgl Exp $`
`12`	`12`	`*`
`13`	`13`	`*-------------------------------------------------------------------------`
`14`	`14`	`*/`
`@@ -143,6 +143,16 @@ MultiExecBitmapAnd(BitmapAndState *node)`
`143`	`143`	`tbm_intersect(result,subresult);`
`144`	`144`	`tbm_free(subresult);`
`145`	`145`	`}`
	`146`	`+`
	`147`	`+/*`
	`148`	`+ * If at any stage we have a completely empty bitmap, we can fall`
	`149`	`+ * out without evaluating the remaining subplans, since ANDing them`
	`150`	`+ * can no longer change the result. (Note: the fact that indxpath.c`
	`151`	`+ * orders the subplans by selectivity should make this case more`
	`152`	`+ * likely to occur.)`
	`153`	`+ */`
	`154`	`+if (tbm_is_empty(result))`
	`155`	`+break;`
`146`	`156`	`}`
`147`	`157`
`148`	`158`	`if (result==NULL)`

Lines changed: 10 additions & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -23,7 +23,7 @@`
`23`	`23`	`* Copyright (c) 2003-2005, PostgreSQL Global Development Group`
`24`	`24`	`*`
`25`	`25`	`* IDENTIFICATION`
`26`		`- * $PostgreSQL: pgsql/src/backend/nodes/tidbitmap.c,v 1.5 2005/07/24 02:25:26 tgl Exp $`
	`26`	`+ * $PostgreSQL: pgsql/src/backend/nodes/tidbitmap.c,v 1.6 2005/08/28 22:47:20 tgl Exp $`
`27`	`27`	`*`
`28`	`28`	`*-------------------------------------------------------------------------`
`29`	`29`	`*/`
`@@ -510,6 +510,15 @@ tbm_intersect_page(TIDBitmap a, PagetableEntry apage, const TIDBitmap *b)`
`510`	`510`	`}`
`511`	`511`	`}`
`512`	`512`
	`513`	`+/*`
	`514`	`+ * tbm_is_empty - is a TIDBitmap completely empty?`
	`515`	`+ */`
	`516`	`+bool`
	`517`	`+tbm_is_empty(constTIDBitmap*tbm)`
	`518`	`+{`
	`519`	`+return (tbm->nentries==0);`
	`520`	`+}`
	`521`	`+`
`513`	`522`	`/*`
`514`	`523`	`* tbm_begin_iterate - prepare to iterate through a TIDBitmap`
`515`	`524`	`*`

Lines changed: 6 additions & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -9,7 +9,7 @@`
`9`	`9`	`*`
`10`	`10`	`*`
`11`	`11`	`* IDENTIFICATION`
`12`		`- * $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.187 2005/07/2820:26:20 tgl Exp $`
	`12`	`+ * $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.188 2005/08/2822:47:20 tgl Exp $`
`13`	`13`	`*`
`14`	`14`	`*-------------------------------------------------------------------------`
`15`	`15`	`*/`
`@@ -538,6 +538,11 @@ choose_bitmap_and(PlannerInfo root, RelOptInfo rel, List *paths)`
`538`	`538`	`* cases, the partial index will sort before competing non-partial`
`539`	`539`	`* indexes and so it makes the right choice, but perhaps we need to`
`540`	`540`	`* work harder.`
	`541`	`+ *`
	`542`	`+ * Note: outputting the selected sub-paths in selectivity order is a good`
	`543`	`+ * thing even if we weren't using that as part of the selection method,`
	`544`	`+ * because it makes the short-circuit case in MultiExecBitmapAnd() more`
	`545`	`+ * likely to apply.`
`541`	`546`	`*/`
`542`	`547`
`543`	`548`	`/* Convert list to array so we can apply qsort */`

Lines changed: 3 additions & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -15,7 +15,7 @@`
`15`	`15`	`*`
`16`	`16`	`* Copyright (c) 2003-2005, PostgreSQL Global Development Group`
`17`	`17`	`*`
`18`		`- * $PostgreSQL: pgsql/src/include/nodes/tidbitmap.h,v 1.1 2005/04/17 22:24:02 tgl Exp $`
	`18`	`+ * $PostgreSQL: pgsql/src/include/nodes/tidbitmap.h,v 1.2 2005/08/28 22:47:20 tgl Exp $`
`19`	`19`	`*`
`20`	`20`	`*-------------------------------------------------------------------------`
`21`	`21`	`*/`
`@@ -49,6 +49,8 @@ extern void tbm_add_tuples(TIDBitmap *tbm, const ItemPointer tids, int ntids);`
`49`	`49`	`externvoidtbm_union(TIDBitmapa,constTIDBitmapb);`
`50`	`50`	`externvoidtbm_intersect(TIDBitmapa,constTIDBitmapb);`
`51`	`51`
	`52`	`+externbooltbm_is_empty(constTIDBitmap*tbm);`
	`53`	`+`
`52`	`54`	`externvoidtbm_begin_iterate(TIDBitmap*tbm);`
`53`	`55`	`externTBMIterateResulttbm_iterate(TIDBitmaptbm);`
`54`	`56`

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