diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/access/heap/heapam.c | 9 | ||||
| -rw-r--r-- | src/test/regress/expected/join.out | 36 | ||||
| -rw-r--r-- | src/test/regress/sql/join.sql | 24 |
3 files changed, 66 insertions, 3 deletions
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c index 4be0dee4de0..82bb9cb33b6 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -1184,7 +1184,12 @@ heap_rescan(TableScanDesc sscan, ScanKey key, bool set_params, scan->rs_vmbuffer = InvalidBuffer; } - Assert(scan->rs_empty_tuples_pending == 0); + /* + * Reset rs_empty_tuples_pending, a field only used by bitmap heap scan, + * to avoid incorrectly emitting NULL-filled tuples from a previous scan + * on rescan. + */ + scan->rs_empty_tuples_pending = 0; /* * The read stream is reset on rescan. This must be done before @@ -1216,8 +1221,6 @@ heap_endscan(TableScanDesc sscan) if (BufferIsValid(scan->rs_vmbuffer)) ReleaseBuffer(scan->rs_vmbuffer); - Assert(scan->rs_empty_tuples_pending == 0); - /* * Must free the read stream before freeing the BufferAccessStrategy. */ diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out index 0246d56aea9..6b16c3a6769 100644 --- a/src/test/regress/expected/join.out +++ b/src/test/regress/expected/join.out @@ -7924,3 +7924,39 @@ where exists (select 1 from j3 (13 rows) drop table j3; +-- Exercise the "skip fetch" Bitmap Heap Scan optimization when candidate +-- tuples are discarded. This may occur when: +-- 1. A join doesn't require all inner tuples to be scanned for each outer +-- tuple, and +-- 2. The inner side is scanned using a bitmap heap scan, and +-- 3. The bitmap heap scan is eligible for the "skip fetch" optimization. +-- This optimization is usable when no data from the underlying table is +-- needed. Use a temp table so it is only visible to this backend and +-- vacuum may reliably mark all blocks in the table all visible in the +-- visibility map. +CREATE TEMP TABLE skip_fetch (a INT, b INT) WITH (fillfactor=10); +INSERT INTO skip_fetch SELECT i % 3, i FROM generate_series(0,30) i; +CREATE INDEX ON skip_fetch(a); +VACUUM (ANALYZE) skip_fetch; +SET enable_indexonlyscan = off; +SET enable_seqscan = off; +EXPLAIN (COSTS OFF) +SELECT t1.a FROM skip_fetch t1 LEFT JOIN skip_fetch t2 ON t2.a = 1 WHERE t2.a IS NULL; + QUERY PLAN +--------------------------------------------------------- + Nested Loop Anti Join + -> Seq Scan on skip_fetch t1 + -> Materialize + -> Bitmap Heap Scan on skip_fetch t2 + Recheck Cond: (a = 1) + -> Bitmap Index Scan on skip_fetch_a_idx + Index Cond: (a = 1) +(7 rows) + +SELECT t1.a FROM skip_fetch t1 LEFT JOIN skip_fetch t2 ON t2.a = 1 WHERE t2.a IS NULL; + a +--- +(0 rows) + +RESET enable_indexonlyscan; +RESET enable_seqscan; diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql index 923e7c5549a..8bfe3b7ba67 100644 --- a/src/test/regress/sql/join.sql +++ b/src/test/regress/sql/join.sql @@ -2904,3 +2904,27 @@ where exists (select 1 from j3 and t1.unique1 < 1; drop table j3; + +-- Exercise the "skip fetch" Bitmap Heap Scan optimization when candidate +-- tuples are discarded. This may occur when: +-- 1. A join doesn't require all inner tuples to be scanned for each outer +-- tuple, and +-- 2. The inner side is scanned using a bitmap heap scan, and +-- 3. The bitmap heap scan is eligible for the "skip fetch" optimization. +-- This optimization is usable when no data from the underlying table is +-- needed. Use a temp table so it is only visible to this backend and +-- vacuum may reliably mark all blocks in the table all visible in the +-- visibility map. +CREATE TEMP TABLE skip_fetch (a INT, b INT) WITH (fillfactor=10); +INSERT INTO skip_fetch SELECT i % 3, i FROM generate_series(0,30) i; +CREATE INDEX ON skip_fetch(a); +VACUUM (ANALYZE) skip_fetch; + +SET enable_indexonlyscan = off; +SET enable_seqscan = off; +EXPLAIN (COSTS OFF) +SELECT t1.a FROM skip_fetch t1 LEFT JOIN skip_fetch t2 ON t2.a = 1 WHERE t2.a IS NULL; +SELECT t1.a FROM skip_fetch t1 LEFT JOIN skip_fetch t2 ON t2.a = 1 WHERE t2.a IS NULL; + +RESET enable_indexonlyscan; +RESET enable_seqscan; |