From: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
---|---|
To: | Nikita Malakhov <hukutoc(at)gmail(dot)com> |
Cc: | "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
Subject: | Re: Pro et contra of preserving pg_proc oids during pg_upgrade |
Date: | 2023-10-16 11:36:21 |
Message-ID: | 202310161136.iswfvsuj7v3w@alvherre.pgsql |
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Lists: | pgsql-hackers |
On 2023-Oct-13, Nikita Malakhov wrote:
> Textual representation requires a long text field because it could
> contain schema, arguments, it is difficult and not effective to be
> saved as part of the data, and must be parsed to retrieve function
> oid.
It is worse than that: the regproc textual representation depends on
search_path. If you store the text now, the meaning could change later,
depending on the search_path that applies at read time.
Of course, the storage for OID is much shorter and not subject to this
problem; but it is subject to the problem that it breaks if you drop and
replace the function, which could happen for instance in an extensions
upgrade script.
I think a better way to store a function's identity is to store the
'identity' column from pg_identify_object(). It is fully qualified and
you can cast to regprocedure with no ambiguity (which gives you an OID,
if you need one). And it should upgrade cleanly.
If you have a regproc column that you want to upgrade, maybe it would
work to do 'ALTER TABLE .. SET TYPE TEXT USING' and turn the value into
pg_identify_object().identity.
--
Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/
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