| From: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
|---|---|
| To: | Rahila Syed <rahilasyed90(at)gmail(dot)com> |
| Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Parallel Index Scans |
| Date: | 2016-10-18 12:02:12 |
| Message-ID: | CAA4eK1+fW0Krn=sRpCJ_DbV-JScKPyvcAOxkqHpDZbt1MLYHUA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Oct 18, 2016 at 4:08 PM, Rahila Syed <rahilasyed90(at)gmail(dot)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
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