Date: Wed, 25 Mar 2026 18:46:11 +0900 (JST)
Message-Id: <20260325.184611.1088077863621666688.ishii@postgresql.org>
To: pgpool-hackers@lists.postgresql.org
Subject: Re: pool_search_relcach does not consider session local cache case
From: Tatsuo Ishii <ishii@postgresql.org>
In-Reply-To: <20260320.115354.1808938375091443061.ishii@postgresql.org>
References: <20260320.115354.1808938375091443061.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.

Patch pushed to down to v4.4.  A test is also added down to v4.5
(v4.4's test script is not suitable to apply the same patch as master
- v4.5).

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