Re: How to generate random bigint - Mailing list pgsql-general

From Thomas Munro
Subject Re: How to generate random bigint
Date
Msg-id CA+hUKGKXT12z4rWCUXVXNKWCdwE-hkALhHCczZWdXdtN_htCDw@mail.gmail.com
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In response to Re: How to generate random bigint  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
On Thu, Dec 21, 2023 at 7:21 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Phillip Diffley <phillip6402@gmail.com> writes:
> > Postgres's random() function generates a random double. That can be
> > converted to a random int for smaller integers, but a double can't
> > represent all of the values in a bigint. Is there a recommended way to
> > generate a random bigint in Postgres?
>
> Doesn't look like there's anything directly exposed for that.
> Since PG v13 you could use gen_random_uuid, if you're careful
> to extract only bits that aren't fixed by the v4 UUID spec.
> pgcrypto's pg_random_bytes() function offers another
> some-assembly-required solution that'd work considerably
> further back.  Or you could make a custom C function that
> leverages pg_strong_random().

Also pg_read_binary_file('/dev/urandom', 0, 8) could be useful
(assuming you're on Unix) if you can figure out how to cast it...



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