| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru> |
| Cc: | Simon Riggs <simon(at)2ndquadrant(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Stas Kelvich <s(dot)kelvich(at)postgrespro(dot)ru>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Read-only access to temp tables for 2PC transactions |
| Date: | 2019-05-24 17:09:21 |
| Message-ID: | 20190524170921.xzrofve2jh5zyfwx@alap3.anarazel.de |
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| Lists: | pgsql-hackers |
Hi,
On 2019-05-24 19:37:15 +0300, Konstantin Knizhnik wrote:
> From my point of view releasing all temporary table locks after preparing of
> 2PC transaction is not technically possible:
> assume that this transaction has updated some tuples of temporary table - them
> are not visible to other transactions until 2PC is committed,
> but since lock is removed, other transactions can update the same tuple.
I don't think tuple level actions are the problem? Those doesn't require
table level locks to be held.
Generally, I fail to see how locks themselves are the problem. The
problem are the catalog entries for the temp table, the relation forks,
and the fact that a session basically couldn't drop (and if created in
that transaction, use) etc the temp table after the PREPARE.
Greetings,
Andres Freund
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