Re: Disconnect from SPI manager on error

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: RekGRpth <rekgrpth(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Disconnect from SPI manager on error
Date: 2019-06-24 15:08:20
Message-ID: CA+Tgmobgzbeks7GhJm_YNnE+JZ0aBfL+P8do-URi-MzhKS8JQg@mail.gmail.com
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On Fri, Jun 21, 2019 at 3:45 AM RekGRpth <rekgrpth(at)gmail(dot)com> wrote:
> >It is not plpgsql's job to clean up after other backend subsystems
> during a transaction abort.
> But plpgsql do clean up on success! I suggest only do cleanup and on exception.

Except that's wrong, because when an error happens, cleanup is - in
most cases - the job of (sub)transaction abort, not something that
should be done by individual bits of code.

PostgreSQL has a centralized system for processing exception cleanup
for a very good reason: there are LOTS of places where errors can be
thrown, and if each of those places has to have its own error cleanup
logic, you end up with a real mess. Instead we've gone the other way:
you can throw an error from anywhere without doing any cleanup, and
it's the job of the error-handling machinery to invoke subtransaction
abort logic, which is responsible for cleaning up whatever mess has
been left behind.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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