Commit0960ae1

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Fix EXPLAIN Bitmap heap scan to count pages with no visible tuples

Previously, bitmap heap scans only counted lossy and exact pages forexplain when there was at least one visible tuple on the page.heapam_scan_bitmap_next_block() returned true only if there was a"valid" page with tuples to be processed. However, the lossy and exactpage counters in EXPLAIN should count the number of pages representedin a lossy or non-lossy way in the constructed bitmap, regardless ofwhether or not the pages ultimately contained visible tuples.Backpatch to all supported versions.Author: Melanie PlagemanDiscussion:https://www.postgresql.org/message-id/CAAKRu_ZwCwWFeL_H3ia26bP2e7HiKLWt0ZmGXPVwPO6uXq0vaA@mail.gmail.comDiscussion:https://www.postgresql.org/message-id/CAAKRu_bxrXeZ2rCnY8LyeC2Ls88KpjWrQ%2BopUrXDRXdcfwFZGA@mail.gmail.com

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-6

lines changed

src
- backend/executor
  - nodeBitmapHeapscan.c
- test/regress/expected
  - partition_prune.out

-6

lines changed

Lines changed: 5 additions & 5 deletions

Original file line number	Diff line number	Diff line change
`@@ -204,6 +204,11 @@ BitmapHeapNext(BitmapHeapScanState *node)`
`204`	`204`
`205`	`205`	`BitmapAdjustPrefetchIterator(node,tbmres);`
`206`	`206`
	`207`	`+if (tbmres->ntuples >=0)`
	`208`	`+node->exact_pages++;`
	`209`	`+else`
	`210`	`+node->lossy_pages++;`
	`211`	`+`
`207`	`212`	`/*`
`208`	`213`	`* We can skip fetching the heap page if we don't need any fields`
`209`	`214`	`* from the heap, and the bitmap entries don't need rechecking,`
`@@ -235,11 +240,6 @@ BitmapHeapNext(BitmapHeapScanState *node)`
`235`	`240`	`continue;`
`236`	`241`	`}`
`237`	`242`
`238`		`-if (tbmres->ntuples >=0)`
`239`		`-node->exact_pages++;`
`240`		`-else`
`241`		`-node->lossy_pages++;`
`242`		`-`
`243`	`243`	`/* Adjust the prefetch target */`
`244`	`244`	`BitmapAdjustPrefetchTarget(node);`
`245`	`245`	`}`

Lines changed: 3 additions & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -2848,6 +2848,7 @@ update ab_a1 set b = 3 from ab where ab.a = 1 and ab.a = ab_a1.a;`
`2848`	`2848`	`Index Cond: (a = 1)`
`2849`	`2849`	`-> Bitmap Heap Scan on ab_a1_b3 ab_a1_3 (actual rows=0 loops=1)`
`2850`	`2850`	`Recheck Cond: (a = 1)`
	`2851`	`+ Heap Blocks: exact=1`
`2851`	`2852`	`-> Bitmap Index Scan on ab_a1_b3_a_idx (actual rows=1 loops=1)`
`2852`	`2853`	`Index Cond: (a = 1)`
`2853`	`2854`	`-> Materialize (actual rows=1 loops=1)`
`@@ -2863,9 +2864,10 @@ update ab_a1 set b = 3 from ab where ab.a = 1 and ab.a = ab_a1.a;`
`2863`	`2864`	`Index Cond: (a = 1)`
`2864`	`2865`	`-> Bitmap Heap Scan on ab_a1_b3 ab_3 (actual rows=0 loops=1)`
`2865`	`2866`	`Recheck Cond: (a = 1)`
	`2867`	`+ Heap Blocks: exact=1`
`2866`	`2868`	`-> Bitmap Index Scan on ab_a1_b3_a_idx (actual rows=1 loops=1)`
`2867`	`2869`	`Index Cond: (a = 1)`
`2868`		`-(34 rows)`
	`2870`	`+(36 rows)`
`2869`	`2871`
`2870`	`2872`	`table ab;`
`2871`	`2873`	`a \| b`

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