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Commit558c9d7

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Fix PHJ match bit initialization.
Hash join tuples reuse the HOT status bit to indicate match statusduring hash join execution. Correct reuse requires clearing the bit inall tuples. Serial hash join and parallel multi-batch hash join do soupon inserting the tuple into the hashtable. Single batch parallel hashjoin and batch 0 of unexpected multi-batch hash joins forgot to do this.It hadn't come up before because hashtable tuple match bits are onlyused for right and full outer joins and parallel ROJ and FOJ wereunsupported.11c2d6f introduced support for parallel ROJ/FOJ butneglected to ensure the match bits were reset.Author: Melanie Plageman <melanieplageman@gmail.com>Reported-by: Richard Guo <guofenglinux@gmail.com>Discussion:https://postgr.es/m/flat/CAMbWs48Nde1Mv%3DBJv6_vXmRKHMuHZm2Q_g4F6Z3_pn%2B3EV6BGQ%40mail.gmail.com
1 parenta282697 commit558c9d7

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3 files changed

+65
-1
lines changed

3 files changed

+65
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lines changed

‎src/backend/executor/nodeHash.c

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@@ -1724,6 +1724,7 @@ ExecParallelHashTableInsert(HashJoinTable hashtable,
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/* Store the hash value in the HashJoinTuple header. */
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hashTuple->hashvalue=hashvalue;
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memcpy(HJTUPLE_MINTUPLE(hashTuple),tuple,tuple->t_len);
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HeapTupleHeaderClearMatch(HJTUPLE_MINTUPLE(hashTuple));
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/* Push it onto the front of the bucket's list */
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ExecParallelHashPushTuple(&hashtable->buckets.shared[bucketno],

‎src/test/regress/expected/join_hash.out

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@@ -955,6 +955,43 @@ $$);
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(1 row)
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rollback to settings;
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-- Hash join reuses the HOT status bit to indicate match status. This can only
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-- be guaranteed to produce correct results if all the hash join tuple match
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-- bits are reset before reuse. This is done upon loading them into the
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-- hashtable.
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SAVEPOINT settings;
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SET enable_parallel_hash = on;
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SET min_parallel_table_scan_size = 0;
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SET parallel_setup_cost = 0;
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SET parallel_tuple_cost = 0;
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CREATE TABLE hjtest_matchbits_t1(id int);
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CREATE TABLE hjtest_matchbits_t2(id int);
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INSERT INTO hjtest_matchbits_t1 VALUES (1);
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INSERT INTO hjtest_matchbits_t2 VALUES (2);
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-- Update should create a HOT tuple. If this status bit isn't cleared, we won't
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-- correctly emit the NULL-extended unmatching tuple in full hash join.
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UPDATE hjtest_matchbits_t2 set id = 2;
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SELECT * FROM hjtest_matchbits_t1 t1 FULL JOIN hjtest_matchbits_t2 t2 ON t1.id = t2.id;
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id | id
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----+----
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1 |
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| 2
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(2 rows)
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-- Test serial full hash join.
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-- Resetting parallel_setup_cost should force a serial plan.
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-- Just to be safe, however, set enable_parallel_hash to off, as parallel full
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-- hash joins are only supported with shared hashtables.
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RESET parallel_setup_cost;
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SET enable_parallel_hash = off;
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SELECT * FROM hjtest_matchbits_t1 t1 FULL JOIN hjtest_matchbits_t2 t2 ON t1.id = t2.id;
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id | id
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----+----
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1 |
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| 2
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(2 rows)
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ROLLBACK TO settings;
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rollback;
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-- Verify that hash key expressions reference the correct
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-- nodes. Hashjoin's hashkeys need to reference its outer plan, Hash's

‎src/test/regress/sql/join_hash.sql

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@@ -506,8 +506,34 @@ $$
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$$);
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rollback to settings;
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rollback;
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-- Hash join reuses the HOT status bit to indicate match status. This can only
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-- be guaranteed to produce correct results if all the hash join tuple match
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-- bits are reset before reuse. This is done upon loading them into the
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-- hashtable.
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SAVEPOINT settings;
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SET enable_parallel_hash=on;
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SET min_parallel_table_scan_size=0;
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SET parallel_setup_cost=0;
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SET parallel_tuple_cost=0;
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CREATETABLEhjtest_matchbits_t1(idint);
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CREATETABLEhjtest_matchbits_t2(idint);
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INSERT INTO hjtest_matchbits_t1VALUES (1);
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INSERT INTO hjtest_matchbits_t2VALUES (2);
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-- Update should create a HOT tuple. If this status bit isn't cleared, we won't
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-- correctly emit the NULL-extended unmatching tuple in full hash join.
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UPDATE hjtest_matchbits_t2set id=2;
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SELECT*FROM hjtest_matchbits_t1 t1 FULLJOIN hjtest_matchbits_t2 t2ONt1.id=t2.id;
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-- Test serial full hash join.
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-- Resetting parallel_setup_cost should force a serial plan.
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-- Just to be safe, however, set enable_parallel_hash to off, as parallel full
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-- hash joins are only supported with shared hashtables.
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RESET parallel_setup_cost;
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SET enable_parallel_hash= off;
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SELECT*FROM hjtest_matchbits_t1 t1 FULLJOIN hjtest_matchbits_t2 t2ONt1.id=t2.id;
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ROLLBACK TO settings;
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rollback;
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-- Verify that hash key expressions reference the correct
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-- nodes. Hashjoin's hashkeys need to reference its outer plan, Hash's

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