Re: Is the Halloween problem an issue in Postgres - Mailing list pgsql-general

From Thomas Kellerer
Subject Re: Is the Halloween problem an issue in Postgres
Date
Msg-id 5f7e3d0e-52da-c5e4-72d6-edcff340d710@gmx.net
Whole thread Raw
In response to Is the Halloween problem an issue in Postgres  (guyren@icloud.com)
Responses Re: Is the Halloween problem an issue in Postgres  (Adrian Klaver <adrian.klaver@aklaver.com>)
Re: Is the Halloween problem an issue in Postgres  (raf <raf@raf.org>)
List pgsql-general
guyren@icloud.com schrieb am 02.12.2020 um 21:27:
> The Halloween problem is that it is a challenge for the database if
> you’re updating a field that is also in the WHERE clause of the same
> query.
>
> I just saw a presentation from someone about how in SQL Server he
> recommended writing changes to a temp table and then writing them to
> the table as being much more efficient.

It sounds strange to me, that this _is_ actually a problem.

Why exactly is that a problem in SQL Server?
And what are the consequences if you do it nevertheless.




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