Horton

Re: Improving connection scalability: GetSnapshotData()

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Daniel Gustafsson <daniel@yesql.se>
Cc: Robert Haas <robertmhaas@gmail.com>, "Jonathan S. Katz" <jkatz@postgresql.org>, Alexander Korotkov <a.korotkov@postgrespro.ru>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Peter Geoghegan <pg@bowt.ie>, Alvaro Herrera <alvherre@2ndquadrant.com>, Bruce Momjian <bruce@momjian.us>, Thomas Munro <thomas.munro@gmail.com>, David Rowley <dgrowleyml@gmail.com>
Date: 2020-07-16T01:25:32Z
Lists: pgsql-hackers

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Hi,

On 2020-07-01 14:42:59 +0200, Daniel Gustafsson wrote:
> This patch no longer applies to HEAD, please submit a rebased version.  I've
> marked it Waiting on Author in the meantime.

Thanks!

Here's a rebased version.  There's a good bit of commit message
polishing and some code and comment cleanup compared to the last
version. Oh, and obviously the conflicts are resolved.

It could make sense to split the conversion of
VariableCacheData->latestCompletedXid to FullTransactionId out from 0001
into is own commit. Not sure...

I've played with splitting 0003, to have the "infrastructure" pieces
separate, but I think it's not worth it. Without a user the changes look
weird and it's hard to have the comment make sense.

Greetings,

Andres Freund

Commits

  1. Try to unbreak 021_row_visibility.pl on mingw.

  2. Fix and test snapshot behavior on standby.

  3. Fix race condition in snapshot caching when 2PC is used.

  4. snapshot scalability: cache snapshots using a xact completion counter.

  5. Fix use of wrong index in ComputeXidHorizons().

  6. Make vacuum a bit more verbose to debug BF failure.

  7. snapshot scalability: Introduce dense array of in-progress xids.

  8. snapshot scalability: Move PGXACT->vacuumFlags to ProcGlobal->vacuumFlags.

  9. snapshot scalability: Move subxact info to ProcGlobal, remove PGXACT.

  10. snapshot scalability: Move PGXACT->xmin back to PGPROC.

  11. snapshot scalability: Don't compute global horizons while building snapshots.

  12. BRIN: Handle concurrent desummarization properly

  13. Track latest completed xid as a FullTransactionId.

  14. Rename VariableCacheData.nextFullXid to nextXid.

  15. snapshot scalability: Move delayChkpt from PGXACT to PGPROC.

  16. Report progress of CREATE INDEX operations