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Commite047783

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Make replace_relid() leave argument unmodified
There are a lot of situations when we share the same pointer to a Bitmapsetstructure across different places. In order to evade undesirable side effectsreplace_relid() function should always return a copy.Reported-by: Richard GuoDiscussion:https://postgr.es/m/CAMbWs4_wJthNtYBL%2BSsebpgF-5L2r5zFFk6xYbS0A78GKOTFHw%40mail.gmail.comReviewed-by: Richard Guo, Andres Freund, Ashutosh Bapat, Andrei Lepikhov
1 parent7d58f23 commite047783

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3 files changed

+29
-3
lines changed

3 files changed

+29
-3
lines changed

‎src/backend/optimizer/plan/analyzejoins.c

Lines changed: 8 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1522,19 +1522,24 @@ replace_varno_walker(Node *node, ReplaceVarnoContext *ctx)
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15231523
/*
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* Substitute newId by oldId in relids.
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*
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* We must make a copy of the original Bitmapset before making any
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* modifications, because the same pointer to it might be shared among
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* different places.
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*/
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staticBitmapset*
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replace_relid(Relidsrelids,intoldId,intnewId)
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{
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if (oldId<0)
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returnrelids;
15311535

1536+
/* Delete relid without substitution. */
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if (newId<0)
1533-
/* Delete relid without substitution. */
1534-
returnbms_del_member(relids,oldId);
1538+
returnbms_del_member(bms_copy(relids),oldId);
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1540+
/* Substitute newId for oldId. */
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if (bms_is_member(oldId,relids))
1537-
returnbms_add_member(bms_del_member(relids,oldId),newId);
1542+
returnbms_add_member(bms_del_member(bms_copy(relids),oldId),newId);
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returnrelids;
15401545
}

‎src/test/regress/expected/join.out

Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -6853,6 +6853,21 @@ on true;
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Filter: (t3.id IS NOT NULL)
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(8 rows)
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-- Check that SJE replaces join clauses involving the removed rel correctly
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explain (costs off)
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select * from emp1 t1
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inner join emp1 t2 on t1.id = t2.id
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left join emp1 t3 on t1.id > 1 and t1.id < 2;
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QUERY PLAN
6862+
----------------------------------------------
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Nested Loop Left Join
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Join Filter: ((t2.id > 1) AND (t2.id < 2))
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-> Seq Scan on emp1 t2
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Filter: (id IS NOT NULL)
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-> Materialize
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-> Seq Scan on emp1 t3
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(6 rows)
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-- We can remove the join even if we find the join can't duplicate rows and
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-- the base quals of each side are different. In the following case we end up
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-- moving quals over to s1 to make it so it can't match any rows.

‎src/test/regress/sql/join.sql

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2610,6 +2610,12 @@ select * from generate_series(1,10) t1(id) left join
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lateral (selectt1.idas t1id,t2.idfrom emp1 t2join emp1 t3ont2.id=t3.id)
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on true;
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-- Check that SJE replaces join clauses involving the removed rel correctly
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explain (costs off)
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select*from emp1 t1
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inner join emp1 t2ont1.id=t2.id
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left join emp1 t3ont1.id>1andt1.id<2;
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-- We can remove the join even if we find the join can't duplicate rows and
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-- the base quals of each side are different. In the following case we end up
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-- moving quals over to s1 to make it so it can't match any rows.

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