Horton

Re: Parallel Index Scans

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Rahila Syed <rahilasyed90@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2016-10-18T12:02:12Z
Lists: pgsql-hackers 
On Tue, Oct 18, 2016 at 4:08 PM, Rahila Syed <rahilasyed90@gmail.com> wrote:
>>Another point which needs some thoughts is whether it is good idea to
>>use index relation size to calculate parallel workers for index scan.
>>I think ideally for index scans it should be based on number of pages
>>to be fetched/scanned from index.
> IIUC, its not possible to know the exact number of pages scanned from an
> index
> in advance.

We can't find the exact numbers of index pages to be scanned, but I
think we can find estimated number of pages to be fetched (refer
cost_index).

-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

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.