public inbox for [email protected]  

help / color / mirror / Atom feed

From: Peter J. Holzer <[email protected]>
To: [email protected]
Subject: Re: Request for Insights on ID Column Migration Approach
Date: Sat, 5 Oct 2024 11:22:52 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <CAE_cSysRBuzmGoRGknPX6Y5sws7qgh0iitYLfQj3g3iiSygzDw@mail.gmail.com>
	<[email protected]>
	<[email protected]>

On 2024-09-27 18:37:35 -0400, Tom Lane wrote:
> "Peter J. Holzer" <[email protected]> writes:
> > As you can see, adding the primary key takes just as much time as
> > creating the unique index. So it doesn't look like PostgreSQL is able to
> > take advantage of the existing index (which makes sense since it still
> > has to create a new index).
> 
> No, but you can attach an existing unique index as a primary key:
> 
> regression=# create table t1 (f1 int not null);
> CREATE TABLE
> regression=# create unique index t1_f1 on t1(f1);
> CREATE INDEX
> regression=# alter table t1 add primary key using index t1_f1;
> ALTER TABLE

Ah, yes. I thought that was possible but I checked the docs[1] and
didn't see it. I checked again before writing this mail and still didn't
see it. Only when I started copy-pasting relevant parts of th synopsis
into the mail did I notice "ADD table_constraint_using_index". I'll get
new glasses soon, I promise. ;-)

        hp


[1] https://www.postgresql.org/docs/current/sql-altertable.html


-- 
   _  | Peter J. Holzer    | Story must make more sense than reality.
|_|_) |                    |
| |   | [email protected]         |    -- Charles Stross, "Creative writing
__/   | http://www.hjp.at/ |       challenge!"


Attachments:

  [application/pgp-signature] signature.asc (833B, 2-signature.asc)
  download

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: [email protected]
  Cc: [email protected], [email protected]
  Subject: Re: Request for Insights on ID Column Migration Approach
  In-Reply-To: <[email protected]>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox