Re: [PATCH] pg_upgrade: add --initdb option to create the new cluster automatically

On 17/07/2026 15:10, Bohyun Lee wrote:
> -O: dropped support with --initdb entirely, as you originally suggested.
> The partial "-c only" forwarding still broke on quoted values with
> spaces. pg_upgrade now rejects -O + --initdb during option parsing, with
> a test and a doc note.

> @@ -244,6 +249,17 @@ parseCommandLine(int argc, char *argv[])
> if (optind < argc)
> pg_fatal("too many command-line arguments (first is \"%s\")", argv[optind]);
>
> + /*
> + * -O passes options to the new cluster's postmaster, but with --initdb
> + * the new cluster is created by initdb, which accepts a different option
> + * set. Rather than guess which -O options initdb also understands, reject
> + * the combination and let the user create the cluster manually (without
> + * --initdb) if they need postmaster-only options.
> + */
> + if (new_cluster.pgopts && user_opts.initdb_new_cluster)
> + pg_fatal("options %s and %s cannot be used together",
> + "-O/--new-options", "--initdb");
> +
> if (!user_opts.sync_method)
> user_opts.sync_method = pg_strdup("fsync");
>

That doesn't sound right. There's indeed no reason think that initdb
would accept the same options as postmaster, so it doesn't make sense to
pass the -O options to initdb. But why forbid using -O with --initdb? I
would imagine that the -O options are passed to the postmaster the same
way with or without --initdb.

Is there a way to pass extra options to initdb? Or do you require the
user to run initdb first or change the settings afterwards, if they want
some additional settings?

> + <para>
> + To discover the old cluster's encoding and locale,
> + <option>--initdb</option> briefly starts the old server in
> + binary-upgrade mode (which disables autovacuum) and stops it again
> + before creating the new cluster. If a compatibility check fails after
> + the new cluster has been created, its data directory is removed
> + automatically, so the upgrade can be retried without manual cleanup.
> + </para>

Hmm, how's that different from how it works without --initdb? pg_upgrade
needs to launch the old cluster anyway to perform the compatibility
checks, right?

- Heikki