From: Tom Lane <tgl@sss.pgh.pa.us>
To: Guillaume Lelarge <guillaume@lelarge.info>
cc: Fabrice Chapuis <fabrice636861@gmail.com>,
        M Sarwar <sarwarmd02@outlook.com>,
        "pgsql-admin@lists.postgresql.org" <pgsql-admin@lists.postgresql.org>
Subject: Re: pg_restore option --clean
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Comments: In-reply-to Guillaume Lelarge <guillaume@lelarge.info>
	message dated "Wed, 21 Feb 2024 15:35:14 +0100"
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Date: Wed, 21 Feb 2024 10:31:57 -0500
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Guillaume Lelarge <guillaume@lelarge.info> writes:
> pg_restore won't drop objects in cascade. There's no option for that. I'd
> guess the reason is that --clean only cleans the object it will restore. If
> other objects depend on it, pg_restore has no way to know how to recreate
> them, and you would end up with a not completely restored database.

Yeah.  The expectation is that --clean will issue the DROP commands
in reverse dependency order, so that no step would require CASCADE.
If one did, it'd imply that pg_dump failed to catalog all the
dependencies in the database, which would be a bug we'd want to know
about.

Now, this theory does fail in at least two practical cases:

* You're trying to use --clean with a selective restore.

* You're trying to restore into a database that has more or
different objects than the source DB did.

But in both cases, blindly using CASCADE seems like a bad idea.
You'd end up with a database that's missing some objects, and
you won't know which ones or how to put them back.

			regards, tom lane