From: Tom Lane <tgl@sss.pgh.pa.us>
To: matt.jibson@gmail.com
Cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #17565: Extended query protocol incorrectly sets TBLOCK_STARTED even though multiple queries can be executed
Date: Mon, 01 Aug 2022 18:21:18 -0400
Message-ID: <2185026.1659392478@sss.pgh.pa.us> (raw)
In-Reply-To: <17565-156f3bd8f262150f@postgresql.org>
References: <17565-156f3bd8f262150f@postgresql.org>
PG Bug reporting form <noreply@postgresql.org> writes:
> The extended query protocol is most often used with the 4 messages in the
> sequence: Parse, Bind, Execute, Sync. Parse, Bind, and Execute all call
> start_xact_command, which will change blockState to TBLOCK_STARTED. However
> it is within the protocol spec to instead do: Parse, Bind, Execute, Parse,
> Bind, Execute, Sync. That is: issue two query executions and then a Sync.
> The Npgsql driver does exactly this at its startup.
> The doc comment for TBLOCK_STARTED says "running single-query transaction",
> but this is a case where a driver can escape that restriction which is
> assumed by the rest of the code. For example, there are various things
> differentiate between STARTED and INPROGRESS or IMPLICIT_INPROGRESS:
> PreventInTransactionBlock, IsInTransactionBlock. Some statements (VACUUM,
> DISCARD ALL) use those functions to prevent their execution in a multi
> statement context, but those can be escaped using the extended protocol.
Hmmm ... I think this is a duplicate of a bug that we just fixed last
week. Please see
https://www.postgresql.org/message-id/flat/17434-d9f7a064ce2a88a3%40postgresql.orghttps://git.postgresql.org/gitweb/?p=postgresql.git&a=commitdiff&h=f92944137
and let us know (preferably on that thread) if you think there's
still more to do.
regards, tom lane
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To: pgsql-bugs@postgresql.org
Cc: tgl@sss.pgh.pa.us, matt.jibson@gmail.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #17565: Extended query protocol incorrectly sets TBLOCK_STARTED even though multiple queries can be executed
In-Reply-To: <2185026.1659392478@sss.pgh.pa.us>
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