Re: reg* checks in pg_upgrade are out of date

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
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