Horton

Re: prevent immature WAL streaming

Nathan Bossart <bossartn@amazon.com>

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From: "Bossart, Nathan" <bossartn@amazon.com>
To: Andres Freund <andres@anarazel.de>, Fujii Masao <masao.fujii@oss.nttdata.com>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Pg Hackers <pgsql-hackers@lists.postgresql.org>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, 蔡梦娟(玊于) <mengjuan.cmj@alibaba-inc.com>, Jakub Wartak <Jakub.Wartak@tomtom.com>
Date: 2021-09-02T00:04:17Z
Lists: pgsql-hackers 
On 9/1/21, 10:06 AM, "Andres Freund" <andres@anarazel.de> wrote:
> On 2021-09-01 15:01:43 +0900, Fujii Masao wrote:
>> Thanks for clarifying that! Unless I misunderstand that, when recovery ends
>> at a partially-flushed segment-spanning record, it sets
>> XLP_FIRST_IS_ABORTED_PARTIAL in the next segment before starting writing
>> new WAL data there. Therefore XLP_FIRST_IS_CONTRECORD or
>> XLP_FIRST_IS_ABORTED_PARTIAL must be set in the next segment following
>> a partially-flushed segment-spanning record. If none of them is set,
>> the validation code in recovery should report an error.
>
> Right. With the small addition that I think we shouldn't just do this for
> segment spanning records, but for all records spanning pages.

This approach seems promising.  I like that it avoids adding extra
work in the hot path for writing WAL.  I'm assuming it won't be back-
patchable, though.

Nathan

Commits

  1. Fix determination of broken LSN in OVERWRITTEN_CONTRECORD

  2. Fix instability in 026_overwrite_contrecord.pl test.

  3. Fix typo

  4. Change recently added test code for stability

  5. Remove unstable, unnecessary test; fix typo

  6. Repair two portability oversights of new test

  7. Fix WAL replay in presence of an incomplete record

  8. Document XLOG_INCLUDE_XID a little better

  9. Revert "Avoid creating archive status ".ready" files too early"

  10. Avoid creating archive status ".ready" files too early

  11. Fix scenario where streaming standby gets stuck at a continuation record.

  12. Teach xlogreader to follow timeline switches

  13. Forbid using pg_xlogfile_name() and pg_xlogfile_name_offset() during