Re: Parallel Index Scans - Mailing list pgsql-hackers

From Amit Kapila
Subject Re: Parallel Index Scans
Date
Msg-id CAA4eK1+fW0Krn=sRpCJ_DbV-JScKPyvcAOxkqHpDZbt1MLYHUA@mail.gmail.com
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In response to Re: Parallel Index Scans  (Rahila Syed <rahilasyed90@gmail.com>)
List 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



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