Message-ID: <ece22f937c7240b2c8e54b5c1bf0b46ec8db1db8.camel@cybertec.at>
Subject: Re: Get info about the index
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: Igor Korot <ikorot01@gmail.com>, Christophe Pettus <xof@thebuild.com>
Cc: Adrian Klaver <adrian.klaver@aklaver.com>, 
 "pgsql-generallists.postgresql.org"
	 <pgsql-general@lists.postgresql.org>
Date: Sat, 26 Jul 2025 21:50:20 +0200
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On Sat, 2025-07-26 at 15:13 -0400, Igor Korot wrote:
> On Sat, Jul 26, 2025, 2:14=E2=80=AFPM Christophe Pettus <xof@thebuild.com=
> wrote:
> > > I want to know all individual things:
> > > - whether the index is unique.
> > > - what type of index it is
> > > - whether the field is ASC or DESC.
> > > - all other individual arams
> >=20
> > pg_index is the source for those.=C2=A0 The one exception is the access=
 method for the index, which is in pg_class.
>=20
> I didn't find the sorting for the field.

That's in pg_index.indoption.

The flags stored there are defined in src/include/catalog/pg_index.h

/*
 * Index AMs that support ordered scans must support these two indoption
 * bits.  Otherwise, the content of the per-column indoption fields is
 * open for future definition.
 */
#define INDOPTION_DESC          0x0001  /* values are in reverse order */
#define INDOPTION_NULLS_FIRST   0x0002  /* NULLs are first instead of last =
*/

So a value of 3 would mean DESC NULLS FIRST.

Yours,
Laurenz Albe