From: | Andres Freund <andres(at)anarazel(dot)de> |
---|---|
To: | Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> |
Cc: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, Pg Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, "Bossart, Nathan" <bossartn(at)amazon(dot)com>, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, 蔡梦娟(玊于) <mengjuan(dot)cmj(at)alibaba-inc(dot)com>, Jakub Wartak <Jakub(dot)Wartak(at)tomtom(dot)com> |
Subject: | Re: prevent immature WAL streaming |
Date: | 2021-09-01 03:15:24 |
Message-ID: | 20210901031524.mdo6aayalmd5jxly@alap3.anarazel.de |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
Hi,
On 2021-09-01 11:34:34 +0900, Fujii Masao wrote:
> On 2021/09/01 0:53, Andres Freund wrote:
> > Of course, we need to be careful to not weaken WAL validity checking too
> > much. How about the following:
> >
> > If we're "aborting" a continued record, we set XLP_FIRST_IS_ABORTED_PARTIAL on
> > the page at which we do so (i.e. the page after the valid end of the WAL).
>
> When do you expect that XLP_FIRST_IS_ABORTED_PARTIAL is set? It's set
> when recovery finds a a partially-flushed segment-spanning record?
> But maybe we cannot do that (i.e., cannot overwrite the page) because
> the page that the flag is set in might have already been archived. No?
I was imagining that XLP_FIRST_IS_ABORTED_PARTIAL would be set in the "tail
end" of a partial record. I.e. if there's a partial record starting in the
successfully archived segment A, but the end of the record, in B, has not been
written to disk before a crash, we'd set XLP_FIRST_IS_ABORTED_PARTIAL at the
end of the valid data in B. Which could not have been archived yet, or we'd
not have a partial record. So we should never need to set the flag on an
already archived page.
Greetings,
Andres Freund
From | Date | Subject | |
---|---|---|---|
Next Message | Greg Nancarrow | 2021-09-01 03:22:22 | Re: Added schema level support for publication. |
Previous Message | Kyotaro Horiguchi | 2021-09-01 03:12:25 | Re: Possible missing segments in archiving on standby |