Horton

Re: BUG #14825: enum type: unsafe use?

Christophe Pettus <christophe.pettus@pgexperts.com>

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From: Christophe Pettus <christophe.pettus@pgexperts.com>
To: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, pgsql-bugs@postgresql.org, pgsql-hackers@postgresql.org, "David E. Wheeler" <david@justatheory.com>
Date: 2017-09-25T17:32:08Z
Lists: pgsql-bugs, pgsql-hackers 
> On Sep 25, 2017, at 07:55, Andrew Dunstan <andrew.dunstan@2ndquadrant.com> wrote:
> Let's ask a couple of users who I think are or have been actually
> hurting on this point. Christophe and David, any opinions?

Since about 90% of what I encounter in this area are automatically-generated migrations, having a clear set of (perhaps restrictive) rules which never fail is the most important.  It's easy to split the CREATE or ALTERs out into their own transaction, and leave usage (such as populating a table from a migration) to a second transaction.

It's not clear to me that this is a vote either way, but I think the easiest thing to explain ("you cannot use a new enum value in the same transaction that created it") is the best in this situation.

Commits

  1. Revert to 9.6 treatment of ALTER TYPE enumtype ADD VALUE.

  2. Remove heuristic same-transaction test from check_safe_enum_use().

  3. Use a blacklist to distinguish original from add-on enum values.

  4. Add support for coordinating record typmods among parallel workers.