Feedback-ID: i2be9440c:Fastmail
From: Fabian Lindfors <fabian@flapplabs.se>
Content-Type: multipart/alternative;
	boundary="Apple-Mail=_A2CDF16B-824F-46CE-B27C-5FE3A432C7B6"
Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3776.700.51.11.1\))
Subject: Custom index access method for primary keys
Message-Id: <872B0CA7-4483-4FC2-8CD8-0A5C08FC0942@flapplabs.se>
Date: Sat, 5 Apr 2025 12:34:24 +0200
To: pgsql-general@postgresql.org
Archived-At: <https://www.postgresql.org/message-id/872B0CA7-4483-4FC2-8CD8-0A5C08FC0942%40flapplabs.se>
Precedence: bulk


--Apple-Mail=_A2CDF16B-824F-46CE-B27C-5FE3A432C7B6
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain;
	charset=utf-8

Hi! I=E2=80=99m working on an index access method that I intend to be =
generic and to replace btree for my specific use case. I noticed though =
that it doesn=E2=80=99t seem to be possible to specify an access method =
when creating a new table and using PRIMARY KEY.

Same applies to altering a table to add a primary key using an existing =
index with a non-btree access method. That hits this check and errors: =
https://github.com/postgres/postgres/blob/4be6a74cfb1ef4c50740e4c2f97a3b47=
8c16de73/src/backend/parser/parse_utilcmd.c#L2480

Wanted to ask if this an intentional limitation and if there is a reason =
why an index access method (if it supports uniqueness) would not be =
usable for a primary key?=

--Apple-Mail=_A2CDF16B-824F-46CE-B27C-5FE3A432C7B6
Content-Transfer-Encoding: quoted-printable
Content-Type: text/html;
	charset=utf-8

<html><head><meta http-equiv=3D"content-type" content=3D"text/html; =
charset=3Dutf-8"></head><body style=3D"overflow-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: after-white-space;">Hi! I=E2=80=99m =
working on an index access method that I intend to be generic and to =
replace btree for my specific use case. I noticed though that it =
doesn=E2=80=99t seem to be possible to specify an access method when =
creating a new table and using PRIMARY KEY.<div><br></div><div>Same =
applies to altering a table to add a primary key using an existing index =
with a non-btree access method. That hits this check and errors:&nbsp;<a =
href=3D"https://github.com/postgres/postgres/blob/4be6a74cfb1ef4c50740e4c2=
f97a3b478c16de73/src/backend/parser/parse_utilcmd.c#L2480">https://github.=
com/postgres/postgres/blob/4be6a74cfb1ef4c50740e4c2f97a3b478c16de73/src/ba=
ckend/parser/parse_utilcmd.c#L2480</a></div><div><br></div><div>Wanted =
to ask if this an intentional limitation and if there is a reason why an =
index access method (if it supports uniqueness) would not be usable for =
a primary key?</div></body></html>=

--Apple-Mail=_A2CDF16B-824F-46CE-B27C-5FE3A432C7B6--