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Re: WIP: WAL prefetch (another approach)

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Dmitry Dolgov <9erthalion6@gmail.com>, David Steele <david@pgmasters.net>, Andres Freund <andres@anarazel.de>, Alvaro Herrera <alvherre@2ndquadrant.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2020-06-05T21:15:14Z
Lists: pgsql-hackers 
On Sat, Jun 6, 2020 at 8:41 AM Tomas Vondra
<tomas.vondra@2ndquadrant.com> wrote:
> BTW in all three cases it happens right after the first restart point in
> the WAL stream:
>
>     LOG:  restored log file "0000000100000108000000FD" from archive
>     LOG:  restartpoint starting: time
>     LOG:  restored log file "0000000100000108000000FE" from archive
>     LOG:  restartpoint complete: wrote 236092 buffers (22.5%); 0 WAL ...
>     LOG:  recovery restart point at 108/FC000028
>     DETAIL:  Last completed transaction was at log time 2020-06-04
>              15:27:00.95139+02.
>     LOG:  recovery no longer prefetching: unexpected pageaddr
>           108/57000000 in log segment 0000000100000108000000FF, offset 0
>     LOG:  restored log file "0000000100000108000000FF" from archive
>
> It looks exactly like this in case of all 3 failures ...

Huh.  Thanks!  I'll try to reproduce this here.

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Fix recovery_prefetch docs.

  2. Prefetch data referenced by the WAL, take II.

  3. Add circular WAL decoding buffer, take II.

  4. Fix generation of ./INSTALL for the distribution tarball

  5. Revert recovery prefetching feature.

  6. Sync guc.c and postgresql.conf.sample with the SGML docs.

  7. Add information of total data processed to replication slot stats.

  8. Doc: Review for "Optionally prefetch referenced data in recovery."

  9. Add circular WAL decoding buffer.

  10. Optionally prefetch referenced data in recovery.

  11. Remove read_page callback from XLogReader.

  12. Provide ReadRecentBuffer() to re-pin buffers by ID.

  13. Provide recovery_init_sync_method=syncfs.

  14. Mark factorial operator, and postfix operators in general, as deprecated.

  15. Rationalize GetWalRcv{Write,Flush}RecPtr().

  16. Support PrefetchBuffer() in recovery.

  17. Prevent hard failures of standbys caused by recycled WAL segments