Message-ID: <f8624649dc10bcb5a908f3054b6377e8573ffc12.camel@cybertec.at>
Subject: Re: Question on indexes
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: sud <suds1434@gmail.com>, pgsql-general
 <pgsql-general@lists.postgresql.org>
Date: Fri, 11 Oct 2024 08:43:37 +0200
In-Reply-To: <CAD=mzVWLN35FHPxN0Ajh2vnDkFLyg9f0vT6EKF9uPm7CYkHS5g@mail.gmail.com>
References: 
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On Fri, 2024-10-11 at 00:19 +0530, sud wrote:
> I have never used any 'hash index' but saw documents in the past suggesti=
ng issues
> around hash index , like WAL doesnt generate for "hash index" which means=
 we can't
> get the hash index back after crash also they are not applied to replicas=
 etc.
> And also these indexes can not be used for range queries , for sorting et=
c.
>=20
> However, we are seeing that one of the databases has multiple hash indexe=
s created.
> So I wanted to understand from experts here, if it's advisable in any spe=
cific
> scenarios over B-tre despite such downsides?
> Note- Its version 15.4 database.

It is safe to use them, but in my tests I didn't find a realistic case wher=
e the were
better than a B-tree index:
https://www.cybertec-postgresql.com/en/postgresql-hash-index-performance/

Keep them if they do the trick for you, but I'd use B-tree indexes instead.

Yours,
Laurenz Albe