Date: Thu, 14 Nov 2019 19:27:29 -0300
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Mark Dilger <hornschnorter@gmail.com>,
	pgsql-hackers@lists.postgresql.org
Subject: Re: Missing dependency tracking for TableFunc nodes
Message-ID: <20191114222729.GA23410@alvherre.pgsql>
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On 2019-Nov-14, Tomas Vondra wrote:

> Isn't that solved by RemoveObjects() doing this?
> 
>    /* Get an ObjectAddress for the object. */
>    address = get_object_address(stmt->removeType,
>                                 object,
>                                 &relation,
>                                 AccessExclusiveLock,
>                                 stmt->missing_ok);
> 
> I've actually done some debugging before sending the patch, and I think
> this prevent the issue you describe.

Hmm .. shouldn't get_statistics_object_oid get a lock on the table that
owns the stats object too?  I think it should be setting *relp to it.
That way, the lock you're proposing to add would be obtained there.
That means it'd be similar to what we do for OBJECT_TRIGGER etc,
get_object_address_relobject().

I admit this'd crash and burn if we had stats on multiple relations,
because there'd be no way to return the multiple relations that would
end up locked.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services