Horton

Re: Parallel tuplesort (for parallel B-Tree index creation)

Alvaro Herrera <alvherre@2ndquadrant.com>

View thread View on postgr.es
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Peter Geoghegan <pg@heroku.com>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>, Claudio Freire <klaussfreire@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Pg Hackers <pgsql-hackers@postgresql.org>, Corey Huinker <corey.huinker@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>
Date: 2016-12-04T01:45:44Z
Lists: pgsql-hackers 
Peter Geoghegan wrote:
> On Mon, Nov 7, 2016 at 8:28 PM, Peter Geoghegan <pg@heroku.com> wrote:
> > What do we need to teach pg_restore about parallel CREATE INDEX, if
> > anything at all? Could this be as simple as a blanket disabling of
> > parallelism for CREATE INDEX from pg_restore? Or, does it need to be
> > more sophisticated than that? I suppose that tools like reindexdb and
> > pgbench must be considered in a similar way.
> 
> I still haven't resolved this question, which seems like the most
> important outstanding question,

I don't think a patch must necessarily consider all possible uses that
the new feature may have.  If we introduce parallel index creation,
that's great; if pg_restore doesn't start using it right away, that's
okay.  You, or somebody else, can still patch it later.  The patch is
still a step forward.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Support parallel btree index builds.

  2. Report an ERROR if a parallel worker fails to start properly.

  3. Transfer state pertaining to pending REINDEX operations to workers.

  4. Add a barrier primitive for synchronizing backends.

  5. Allow DML commands that create tables to use parallel query.

  6. Refactor GetOldestXmin() to use flags

  7. Fix regression in parallel planning against inheritance tables.

  8. Don't create "holes" in BufFiles, in the new logtape code.

  9. Simplify the code for logical tape read buffers.

  10. Fix excessive memory consumption in the new sort pre-reading code.

  11. Implement binary heap replace-top operation in a smarter way.

  12. Cosmetic code cleanup in commands/extension.c.

  13. Speed up planner's scanning for parallel-query hazards.

  14. Read from the same worker repeatedly until it returns no tuple.

  15. Improve tuplesort.c to support variable merge order. The original coding