Re: Optimising a two column OR check - Mailing list pgsql-performance

From Justin Pryzby
Subject Re: Optimising a two column OR check
Date
Msg-id 20191012144336.GA4475@telsasoft.com
Whole thread Raw
In response to Optimising a two column OR check  (Ivan Voras <ivoras@gmail.com>)
Responses Re: Optimising a two column OR check  (Jeff Janes <jeff.janes@gmail.com>)
List pgsql-performance
On Sat, Oct 12, 2019 at 04:39:56PM +0200, Ivan Voras wrote:
> With seqscan disabled, I get this plan on 9.6:
>  Bitmap Heap Scan on friend  (cost=8.42..19.01 rows=14 width=8)
...
> I expected to get an index-only scan in this situation, as that would be a
> very common query. Is there a way to actually make this sort of query
> resolvable with an index-only scan? Maybe a different table structure would
> help?

The v11 release notes have this relevant item:

https://www.postgresql.org/docs/11/release-11.html
|Allow bitmap scans to perform index-only scans when possible (Alexander Kuzmenkov)

Justin



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