Re: Why a bitmap scan in this case? - Mailing list pgsql-performance

From Jon Zeppieri
Subject Re: Why a bitmap scan in this case?
Date
Msg-id CAKfDxxwffetLV3UKdLZR_zUOe4odDLges-v7kkTtasfMQ2a2NQ@mail.gmail.com
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In response to Re: Why a bitmap scan in this case?  (Jon Zeppieri <zeppieri@gmail.com>)
List pgsql-performance
On Thu, Dec 19, 2024 at 2:09 PM Jon Zeppieri <zeppieri@gmail.com> wrote:
>
> The row estimate is not good. The query estimates 317919 rows but
> there are only 27701. There is some correlation here; if end_on is
> null, start_on is a lot more likely to be recent, so maybe extended
> statistics would be useful here.
>

Though, given that the index only contains rows where end_on is null,
it seems odd that the planner would estimate more rows than are
present in the index. That said, I have no idea whether the planner
uses that sort of information. -J



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