Horton

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

Thomas Munro <thomas.munro@enterprisedb.com>

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From: Thomas Munro <thomas.munro@enterprisedb.com>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Rushabh Lathia <rushabh.lathia@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Heikki Linnakangas <hlinnaka@iki.fi>, Pg Hackers <pgsql-hackers@postgresql.org>, Corey Huinker <corey.huinker@gmail.com>
Date: 2017-11-03T01:39:49Z
Lists: pgsql-hackers 
On Fri, Nov 3, 2017 at 2:24 PM, Peter Geoghegan <pg@bowt.ie> wrote:
> Thomas Munro <thomas.munro@enterprisedb.com> wrote:
>> That way you don't have to opt in to BufFile's
>> double buffering and segmentation schemes just to get shared file
>> clean-up, if for some reason you want direct file handles.
>
> Is that something that you really think is possible?

It's pretty far fetched, but maybe shared temporary relation files
accessed via smgr.c/md.c?  Or maybe future things that don't want to
read/write through a buffer but instead want to mmap it.

-- 
Thomas Munro
http://www.enterprisedb.com

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