public inbox for [email protected]  

help / color / mirror / Atom feed

From: Fujii Masao <[email protected]>
To: Etsuro Fujita <[email protected]>
To: [email protected]
Subject: Re: pgsql: postgres_fdw: Inherit the local transaction's access/deferrable
Date: Mon, 2 Jun 2025 12:03:50 +0900
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>



On 2025/06/01 17:34, Etsuro Fujita wrote:
> postgres_fdw: Inherit the local transaction's access/deferrable modes.
> 
> Previously, postgres_fdw always 1) opened a remote transaction in READ
> WRITE mode even when the local transaction was READ ONLY, causing a READ
> ONLY transaction using it that references a foreign table mapped to a
> remote view executing a volatile function to write in the remote side,
> and 2) opened the remote transaction in NOT DEFERRABLE mode even when
> the local transaction was DEFERRABLE, causing a SERIALIZABLE READ ONLY
> DEFERRABLE transaction using it to abort due to a serialization failure
> in the remote side.
> 
> To avoid these, modify postgres_fdw to open a remote transaction in the
> same access/deferrable modes as the local transaction.  This commit also
> modifies it to open a remote subtransaction in the same access mode as
> the local subtransaction.
> 
> Although these issues exist since the introduction of postgres_fdw,
> there have been no reports from the field.  So it seems fine to just fix
> them in master only.

I'm not sure this change should be considered a bug fix,
since the current behavior of postgres_fdw with a local read-only
transaction isn't clearly documented. Some users might see this
as a behavioral change rather than a fix. Anyway if we go with it,
shouldn't we document the change in the v18 release notes?

Regards,

-- 
Fujii Masao
NTT DATA Japan Corporation

view thread (12+ 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: pgsql: postgres_fdw: Inherit the local transaction's access/deferrable
  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