Date: Tue, 12 Jan 2021 12:08:04 -0300
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Michael Paquier <michael@paquier.xyz>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>,
	Tom Lane <tgl@sss.pgh.pa.us>, exclusion@gmail.com,
	pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #16577: Segfault on altering a table located in a dropped
 tablespace
Message-ID: <20210112150804.GA27528@alvherre.pgsql>
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On 2021-Jan-12, Michael Paquier wrote:

> +       /*
> +        * If a tablespace is specified, removal of that tablespace is normally
> +        * protected by the existence of a physical file; but for relations with
> +        * no files, add a pg_shdepend entry to account for that.
> +        */
> +       if (!create_storage && reltablespace != InvalidOid)
>
> On HEAD, could we consider using this dependency link even for
> relations that have physical files, and remove the physical file
> check?  Could that make the dependency handling cleaner?

That would bloat the catalog with a lot of entries for stuff that can be
detected with the current method.  Did you notice that the code is
removing an "#ifdef NOT_USED" line to enable existing code?  Well, when
I wrote this code in 2005 (59d1b3d99e69) it was doing things as you
suggest, but in the end we decided that it wasn't necessary so it was
taken out.

-- 
Álvaro Herrera                            39°49'30"S 73°17'W
"Someone said that it is at least an order of magnitude more work to do
production software than a prototype. I think he is wrong by at least
an order of magnitude."                              (Brian Kernighan)