On Fri, Feb 28, 2020 at 08:35:33PM -0500, Tom Lane wrote:
Tomas Vondra <tomas.von...@2ndquadrant.com> writes:
I think we might check if there are any attributes with the given data
type, and allow the change if there are none. That would still allow the
change when the type is used only for things like function parameters
etc. But we'd also have to check for domains (recursively).
Still has race conditions.
Yeah, I have no problem believing that.
One thing I haven't mentioned in the original message is CASCADE. It
seems useful to optionally change storage for all attributes with the
given data type. But I'm not sure it's actually a good idea, and the
amount of code seems non-trivial (it'd have to copy quite a bit of code
from ALTER TABLE).
You'd need a moderately strong lock on each such table, which means
there'd be serious deadlock hazards. I'm dubious that it's worth
troubling with.
Yeah, I don't plan to do this in v1 (and I have no immediate plan to
work on it after that). But I wonder how is the deadlock risk any
different compared e.g. to DROP TYPE ... CASCADE?
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
