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Commitf9c655d

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Fix alias matching in transformLockingClause().
When locking a specific named relation for a FOR [KEY] UPDATE/SHAREclause, transformLockingClause() finds the relation to lock byscanning the rangetable for an RTE with a matching eref->aliasname.However, it failed to account for the visibility rules of a join RTE.If a join RTE doesn't have a user-supplied alias, it will have agenerated eref->aliasname of "unnamed_join" that is not visible as arelation name in the parse namespace. Such an RTE needs to be skipped,otherwise it might be found in preference to a regular base relationwith a user-supplied alias of "unnamed_join", preventing it from beinglocked.In addition, if a join RTE doesn't have a user-supplied alias, butdoes have a join_using_alias, then the RTE needs to be matched usingthat alias rather than the generated eref->aliasname, otherwise amisleading "relation not found" error will be reported rather than a"join cannot be locked" error.Backpatch all the way, except for the second part which only goes backto 14, where JOIN USING aliases were added.Dean Rasheed, reviewed by Tom Lane.Discussion:https://postgr.es/m/CAEZATCUY_KOBnqxbTSPf=7fz9HWPnZ5Xgb9SwYzZ8rFXe7nb=w@mail.gmail.com
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‎src/backend/parser/analyze.c

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@@ -2809,6 +2809,15 @@ transformLockingClause(ParseState *pstate, Query *qry, LockingClause *lc,
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++i;
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if (!rte->inFromCl)
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continue;
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/*
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* A join RTE without an alias is not visible as a relation
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* name and needs to be skipped (otherwise it might hide a
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* base relation with the same name).
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*/
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if (rte->rtekind==RTE_JOIN&&rte->alias==NULL)
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continue;
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if (strcmp(rte->eref->aliasname,thisrel->relname)==0)
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{
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switch (rte->rtekind)

‎src/test/regress/expected/join.out

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@@ -2449,6 +2449,14 @@ ERROR: column t1.x does not exist
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LINE 1: select t1.x from t1 join t3 on (t1.a = t3.x);
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^
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HINT: Perhaps you meant to reference the column "t3.x".
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-- Test matching of locking clause with wrong alias
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select t1.*, t2.*, unnamed_join.* from
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t1 join t2 on (t1.a = t2.a), t3 as unnamed_join
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for update of unnamed_join;
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a | b | a | b | x | y
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---+---+---+---+---+---
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(0 rows)
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--
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-- regression test for 8.1 merge right join bug
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--

‎src/test/regress/sql/join.sql

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@@ -509,6 +509,12 @@ select * from t1 left join t2 on (t1.a = t2.a);
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selectt1.xfrom t1join t3on (t1.a=t3.x);
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-- Test matching of locking clause with wrong alias
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select t1.*, t2.*, unnamed_join.*from
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t1join t2on (t1.a=t2.a), t3as unnamed_join
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forupdate of unnamed_join;
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--
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-- regression test for 8.1 merge right join bug
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--

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