From: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
Subject: Re: reg* checks in pg_upgrade are out of date
To: Andres Freund <andres@anarazel.de>, pgsql-hackers@postgresql.org,
 Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>
References: <20181122001214.p7assjzejyyul32l@alap3.anarazel.de>
Message-ID: <037e152a-cb25-3bcb-4f35-bdc9988f8204@2ndQuadrant.com>
Date: Thu, 22 Nov 2018 08:49:23 -0500
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On 11/21/18 7:12 PM, Andres Freund wrote:
> Hi,
>
> It seems the list of reg* types and the check for them in pg_upgrade
> have gone out of sync. We have the following reg* types:
>
>   SELECT typname FROM pg_type WHERE typname LIKE 'reg%' order by typname;
> ┌───────────────┐
> │    typname    │
> ├───────────────┤
> │ regclass      │
> │ regconfig     │
> │ regdictionary │
> │ regnamespace  │
> │ regoper       │
> │ regoperator   │
> │ regproc       │
> │ regprocedure  │
> │ regrole       │
> │ regtype       │
> └───────────────┘
> (10 rows)
>
> but pg_upgrade doesn't consider all of them:
>
>          /*
>           * While several relkinds don't store any data, e.g. views, they can
>           * be used to define data types of other columns, so we check all
>           * relkinds.
>           */
>          res = executeQueryOrDie(conn,
>                                  "SELECT n.nspname, c.relname, a.attname "
>                                  "FROM   pg_catalog.pg_class c, "
>                                  "       pg_catalog.pg_namespace n, "
>                                  "       pg_catalog.pg_attribute a "
>                                  "WHERE  c.oid = a.attrelid AND "
>                                  "       NOT a.attisdropped AND "
>                                  "       a.atttypid IN ( "
>                                  "           'pg_catalog.regproc'::pg_catalog.regtype, "
>                                  "           'pg_catalog.regprocedure'::pg_catalog.regtype, "
>                                  "           'pg_catalog.regoper'::pg_catalog.regtype, "
>                                  "           'pg_catalog.regoperator'::pg_catalog.regtype, "
>          /* regclass.oid is preserved, so 'regclass' is OK */
>          /* regtype.oid is preserved, so 'regtype' is OK */
>                                  "           'pg_catalog.regconfig'::pg_catalog.regtype, "
>                                  "           'pg_catalog.regdictionary'::pg_catalog.regtype) AND "
>                                  "       c.relnamespace = n.oid AND "
>                                  "       n.nspname NOT IN ('pg_catalog', 'information_schema')");
>
> (I don't get the order here btw)
>
> ISTM when regrole and regnamespace were added, pg_upgrade wasn't
> considered. It turns out that regrole is safe, because we preserve user
> oids, but regnamespace isn't afaict.  I don't think it's extremely
> likely that users store such reg* columns in tables, but we probably
> still should fix this.
>

yeah, I think you're right, both about the need to fix it and the 
unlikelihood of it occurring in the wild.


cheers


andrew


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