Horton

Re: Improving connection scalability: GetSnapshotData()

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Thomas Munro <thomas.munro@gmail.com>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>, Daniel Gustafsson <daniel@yesql.se>, 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>, Bruce Momjian <bruce@momjian.us>, David Rowley <dgrowleyml@gmail.com>
Date: 2020-08-12T00:19:38Z
Lists: pgsql-hackers 
Hi,

On 2020-07-29 19:20:04 +1200, Thomas Munro wrote:
> On Wed, Jul 29, 2020 at 6:15 PM Thomas Munro <thomas.munro@gmail.com> wrote:
> > +static inline FullTransactionId
> > +FullXidViaRelative(FullTransactionId rel, TransactionId xid)
> >
> > I'm struggling to find a better word for this than "relative".
> 
> The best I've got is "anchor" xid.  It is an xid that is known to
> limit nextFullXid's range while the receiving function runs.

Thinking about it, I think that relative is a good descriptor. It's just
that 'via' is weird. How about: FullXidRelativeTo?

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