From: Tom Lane <tgl@sss.pgh.pa.us>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Fix parse_cte.c's failure to examine sub-WITHs in DML statements
Date: Sat, 05 Apr 2025 19:01:59 +0000
Message-ID: <E1u18mF-002qny-2g@gemulon.postgresql.org> (raw)
Fix parse_cte.c's failure to examine sub-WITHs in DML statements.
makeDependencyGraphWalker thought that only SelectStmt nodes could
contain a WithClause. Which was true in our original implementation
of WITH, but astonishingly we missed updating this code when we added
the ability to attach WITH to INSERT/UPDATE/DELETE (and later MERGE).
Moreover, since it was coded to deliberately block recursion to a
WithClause, even updating raw_expression_tree_walker didn't save it.
The upshot of this was that we didn't see references to outer CTE
names appearing within an inner WITH, and would neither complain about
disallowed recursion nor account for such references when sorting CTEs
into a usable order. The lack of complaints about this is perhaps not
so surprising, because typical usage of WITH wouldn't hit either case.
Still, it's pretty broken; failing to detect recursion here leads to
assert failures or worse later on.
Fix by factoring out the processing of sub-WITHs into a new function
WalkInnerWith, and invoking that for all the statement types that
can have WITH.
Bug: #18878
Reported-by: Yu Liang <luy70@psu.edu>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/18878-a26fa5ab6be2f2cf@postgresql.org
Backpatch-through: 13
Branch
------
REL_14_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/754a3d82d79cc3d7040cfadaf9c8cd1579684ee6
Modified Files
--------------
src/backend/parser/parse_cte.c | 139 +++++++++++++++++++++++++------------
src/test/regress/expected/with.out | 8 +++
src/test/regress/sql/with.sql | 7 ++
3 files changed, 111 insertions(+), 43 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: tgl@sss.pgh.pa.us, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Fix parse_cte.c's failure to examine sub-WITHs in DML statements
In-Reply-To: <E1u18mF-002qny-2g@gemulon.postgresql.org>
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