public inbox for [email protected]  

help / color / mirror / Atom feed

From: Tatsuo Ishii <[email protected]>
To: [email protected]
Cc: [email protected]
Subject: Re: Proposal: Recent mutated table tracking in memory
Date: Fri, 26 Jun 2026 07:40:28 +0900 (JST)
Message-ID: <[email protected]> (raw)
In-Reply-To: <CACeKOO31reCtDYU1twicmqgdEStCJXWJ6P4LMFMYytaYaGew-A@mail.gmail.com>
References: <CACeKOO02V7_SBpCUJWG7yS-ABNEXzAAU-vb+JrY=rD8yBiiy0g@mail.gmail.com>
	<[email protected]>
	<CACeKOO31reCtDYU1twicmqgdEStCJXWJ6P4LMFMYytaYaGew-A@mail.gmail.com>

Hi Nadav,

> Hi Tatsuo,
> 
> Good catch -- that was a bug, and chasing it down turned up a second
> one in the same area.
> 
> The original problem you described: the flush ran in dml_adaptive()
> while pgpool was *routing* the COMMIT, before the COMMIT was sent to
> the backend.  So a COMMIT that later failed (your deferred-constraint
> example) had already marked the tables, even though the writes rolled
> back.
> 
> My first instinct was to just move the flush to handle_query_context(),
> where reaching CommandComplete for the COMMIT means it succeeded.  But
> that path resolves table/database OIDs via pool_table_name_to_oid() /
> the relcache, which on a cache miss issues a do_query() -- and at that
> point the COMMIT response is still being read from the backend, so
> injecting a query desyncs the protocol and hangs the session.  Testing
> caught this immediately.
> 
> It turned out the existing autocommit marking branch had the very same
> hazard: pool_extract_table_oids() in handle_query_context() also does a
> relcache do_query() on a miss, so e.g. "DROP TABLE IF EXISTS <nonexistent>"
> (an uncacheable name -> guaranteed miss) reliably hung the session too.

Are you saying that the non patched pgpool has a problem?
I tried following queries with master branch and found no hang.

BEGIN;
DROP TABLE IF EXISTS non_existent_table;
COMMIT;

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

view thread (61+ messages)  latest in thread

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: [email protected]
  Cc: [email protected], [email protected], [email protected]
  Subject: Re: Proposal: Recent mutated table tracking in memory
  In-Reply-To: <[email protected]>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox