Horton

Re: Improving connection scalability: GetSnapshotData()

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Andres Freund <andres@anarazel.de>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Ian Barwick <ian.barwick@2ndquadrant.com>, Robert Haas <robertmhaas@gmail.com>, Thomas Munro <thomas.munro@gmail.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Daniel Gustafsson <daniel@yesql.se>, "Jonathan S. Katz" <jkatz@postgresql.org>, Alexander Korotkov <a.korotkov@postgrespro.ru>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Peter Geoghegan <pg@bowt.ie>, Bruce Momjian <bruce@momjian.us>, David Rowley <dgrowleyml@gmail.com>
Date: 2020-09-15T02:56:24Z
Lists: pgsql-hackers 
On Mon, Sep 14, 2020 at 05:42:51PM -0700, Andres Freund wrote:
> My test uses IPC::Run - although I'm indirectly 'use'ing, which I guess
> isn't pretty. Just as 013_crash_restart.pl already did (even before
> psql/t/010_tab_completion.pl). I am mostly wondering whether we could
> avoid copying the utility functions into multiple test files...
> 
> Does IO::Pty work on windows? Given that currently the test doesn't use
> a pty and that there's no benefit I can see in requiring one, I'm a bit
> hesitant to go there?

Per https://metacpan.org/pod/IO::Tty:
"Windows is now supported, but ONLY under the Cygwin environment, see
http://sources.redhat.com/cygwin/."

So I would suggest to make stuff a soft dependency (as Tom is
hinting?), and not worry about Windows specifically.  It is not like
what we are dealing with here is specific to Windows anyway, so you
would have already sufficient coverage.  I would not mind if any
refactoring is done later, once we know that the proposed test is
stable in the buildfarm as we would get a better image of what part of
the facility overlaps across multiple tests.
--
Michael

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