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Re: WIP: WAL prefetch (another approach)

Tomas Vondra <tomas.vondra@enterprisedb.com>

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From: Tomas Vondra <tomas.vondra@enterprisedb.com>
To: Thomas Munro <thomas.munro@gmail.com>
Cc: Daniel Gustafsson <daniel@yesql.se>, Stephen Frost <sfrost@snowman.net>, Alvaro Herrera <alvherre@2ndquadrant.com>, Andres Freund <andres@anarazel.de>, David Steele <david@pgmasters.net>, Dmitry Dolgov <9erthalion6@gmail.com>, Jakub Wartak <Jakub.Wartak@tomtom.com>, Tom Lane <tgl@sss.pgh.pa.us>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2021-11-26T23:34:21Z
Lists: pgsql-hackers 
On 11/26/21 22:16, Thomas Munro wrote:
> On Fri, Nov 26, 2021 at 11:32 AM Tomas Vondra
> <tomas.vondra@enterprisedb.com> wrote:
>> The results are pretty good / similar to previous results. Replaying the
>> 1h worth of work on a smaller machine takes ~5:30h without prefetching
>> (master or with prefetching disabled). With prefetching enabled this
>> drops to ~2h (default config) and ~1h (with tuning).
> 
> Thanks for testing!  Wow, that's a nice graph.
> 
> This has bit-rotted already due to Robert's work on ripping out
> globals, so I'll post a rebase early next week, and incorporate your
> code feedback.
> 

One thing that's not clear to me is what happened to the reasons why 
this feature was reverted in the PG14 cycle?

regards

-- 
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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