Re: Refreshing subscription relation state inside a transaction block

From: Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Petr Jelinek <petr(dot)jelinek(at)2ndquadrant(dot)com>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Refreshing subscription relation state inside a transaction block
Date: 2017-07-28 04:13:23
Message-ID: CAD21AoDZjk0qdHn704TUz03Haiqpc4O9zQ1H_h03-Dn3_NZc9A@mail.gmail.com
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On Thu, Jul 27, 2017 at 9:31 AM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> On Wed, Jul 26, 2017 at 10:29 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> On Mon, Jun 19, 2017 at 4:30 AM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>>>> I think that either of the options you suggested now would be better.
>>>> We'll need that for stopping the tablesync which is in progress during
>>>> DropSubscription as well as those will currently still keep running. I
>>>> guess we could simply just register syscache callback, the only problem
>>>> with that is we'd need to AcceptInvalidationMessages regularly while we
>>>> do the COPY which is not exactly free so maybe killing at the end of
>>>> transaction would be better (both for refresh and drop)?
>>>
>>> Attached patch makes table sync worker check its relation subscription
>>> state at the end of COPY and exits if it has disappeared, instead of
>>> killing table sync worker in DDL. There is still a problem that a
>>> table sync worker for a large table can hold a slot for a long time
>>> even after its state is deleted. But it would be for PG11 item.
>>
>> Do we still need to do something about this? Should it be an open item?
>>
>
> Thank you for looking at this.
>
> Yeah, I think it should be added to the open item list. The patch is
> updated by Petr and discussed on another thread[1] that also addresses
> other issues of subscription codes. 0004 patch of that thread is an
> updated patch of the patch attached on this thread.
>

Does anyone have any opinions? Barring any objections, I'll add this
to the open item list.

Regards,

--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center

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