scan->rs_vmbuffer=InvalidBuffer;

}

Assert(scan->rs_empty_tuples_pending==0);

scan->rs_empty_tuples_pending=0;

if (BufferIsValid(scan->rs_vmbuffer))

ReleaseBuffer(scan->rs_vmbuffer);

Assert(scan->rs_empty_tuples_pending==0);

(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;

andt1.unique1<1;

droptable j3;

CREATE TEMP TABLE skip_fetch (aINT, bINT) WITH (fillfactor=10);

INSERT INTO skip_fetchSELECT i %3, iFROM generate_series(0,30) i;

CREATEINDEXON skip_fetch(a);

VACUUM (ANALYZE) skip_fetch;

SET enable_indexonlyscan= off;

SET enable_seqscan= off;

EXPLAIN (COSTS OFF)

SELECTt1.aFROM skip_fetch t1LEFT JOIN skip_fetch t2ONt2.a=1WHEREt2.a ISNULL;

SELECTt1.aFROM skip_fetch t1LEFT JOIN skip_fetch t2ONt2.a=1WHEREt2.a ISNULL;

RESET enable_indexonlyscan;

RESET enable_seqscan;