| From: | Michael Paquier <michael(dot)paquier(at)gmail(dot)com> |
|---|---|
| To: | Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com> |
| Cc: | Petr Jelinek <petr(dot)jelinek(at)2ndquadrant(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: logical replication and PANIC during shutdown checkpoint in publisher |
| Date: | 2017-05-02 14:08:41 |
| Message-ID: | CAB7nPqRPPMwm0Y8YO6ehn=CUK-NMvS8rK8C_B1tQT_D8i5RvkA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, May 2, 2017 at 9:30 PM, Peter Eisentraut
<peter(dot)eisentraut(at)2ndquadrant(dot)com> wrote:
> On 5/2/17 03:11, Petr Jelinek wrote:
>> logical decoding can theoretically
>> do HOT pruning (even if the chance is really small) so it's not safe to
>> start logical replication either.
>
> This seems a bit impossible to resolve. On the one hand, we want to
> allow streaming until after the shutdown checkpoint. On the other hand,
> streaming itself might produce new WAL.
It would be nice to split things into two:
- patch 1 adding the signal handling that wins a backpatch.
- patch 2 fixing the side cases with logical decoding.
> Can we prevent HOT pruning during logical decoding?
It does not sound much difficult to do, couldn't you just make it a
no-op with am_walsender?
--
Michael
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