Re: Query plan for "id IS NULL" on PK

From: Rob Sargent <robjsargent(at)gmail(dot)com>
To: "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>
Cc: pgsql-general(at)lists(dot)postgresql(dot)org
Subject: Re: Query plan for "id IS NULL" on PK
Date: 2023-02-14 22:36:32
Message-ID: 8e744026-7547-5d4d-b76c-ca152881ccce@gmail.com
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On 2/14/23 15:30, David G. Johnston wrote:
> On Tue, Feb 14, 2023 at 3:25 PM Rob Sargent <robjsargent(at)gmail(dot)com> wrote:
>
>
> When will id be null in a primary key?
>
>
> The OP seems to be aware of this...
>
> "We cannot change the query being executed. Is there any way we can
> make the query planner ignore `OR (id IS NULL)` (as that will never be
> the case for the PK) and use both `id` clauses in the index condition?"
>
> David J.
>
Yes, agreed.
But if the query is supposed to be generic and re-used in a situation
where id could be null, wouldn't the null id records be fetched every time?

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