Horton

Re: Core dump happens when execute sql CREATE VIEW v1(c1) AS (SELECT ('4' COLLATE "C")::INT FROM generate_series(1, 10));

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Yulin PEI <ypeiae@connect.ust.hk>
Cc: "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Date: 2021-04-12T16:59:43Z
Lists: pgsql-hackers

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Yulin PEI <ypeiae@connect.ust.hk> writes:
>     I found it could cause a crash when executing sql statement: `CREATE VIEW v1(c1) AS (SELECT ('4' COLLATE "C")::INT FROM generate_series(1, 10)); ` in postgres 13.2 release.

Nice catch.  I don't think the code in DefineVirtualRelation is wrong:
exprCollation shouldn't report any collation for an expression of a
non-collatable type.  Rather the problem is with an old kluge in
coerce_type(), which will push a type coercion underneath a CollateExpr
... without any mind for the possibility that the coercion result isn't
collatable.  So the right fix is more or less the attached.

			regards, tom lane

Commits

  1. Remove no-longer-relevant test case.

  2. Fix old bug with coercing the result of a COLLATE expression.