Horton

Re: Parallel Index Scans

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Peter Geoghegan <pg@heroku.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2016-10-20T17:03:24Z
Lists: pgsql-hackers 
On Wed, Oct 19, 2016 at 11:07 PM, Amit Kapila <amit.kapila16@gmail.com> wrote:
>> Ideally, the parallel_workers storage parameter will rarely be
>> necessary because the optimizer will generally do the right thing in
>> all case.
>
> Yeah, we can choose not to provide any parameter for parallel index
> scans, but some users might want to have a parameter similar to
> parallel table scans, so it could be handy for them to use.

I think the parallel_workers reloption should override the degree of
parallelism for any sort of parallel scan on that table.  Had I
intended it to apply only to sequential scans, I would have named it
differently.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Commits

  1. Replace min_parallel_relation_size with two new GUCs.

  2. Factor out logic for computing number of parallel workers.

  3. Support condition variables.

  4. Allow parallel custom and foreign scans.

  5. Add a C API for parallel heap scans.