Date: Fri, 20 Mar 2026 11:53:54 +0900 (JST)
Message-Id: <20260320.115354.1808938375091443061.ishii@postgresql.org>
To: pgpool-hackers@lists.postgresql.org
Subject: pool_search_relcach does not consider session local cache case
From: Tatsuo Ishii <ishii@postgresql.org>
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While looking into https://github.com/pgpool/pgpool2/issues/154
I found a bug with pool_search_relcach.

pool_search_relcache does not consider the session local cache case
such as temp table search. It creates the search result in shared
relation cache even if the relation cache is session local. As a
result subsequent query against the session local cache is returned
from the shared relation cache. This could cause wrong
result. Example:

create table t1(i int);
select * from t1; -- info "t1 is not a temp table" is registered in shared cache
drop table t1;
create temp table t1(i int);
select * from t1; -- shared cache tells that t1 is not temp table and it could be load balanced,
       	      	  -- it could access non existent table from standby nodes.

Fix is, to not register a temp table to shared relation cache if it's
a session local cache.

Patch attached.

Best regards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp

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