Arctic Toucan <arctic_toucan@hotmail.com> writes:
> -- Is there something magical about the hash aggregate estimate of 200 rows?
Yeah, it's the default :-(
> Is this a bug, or some subtlety of the Postgres query planner?
It's an, um, known deficiency --- the planner hasn't got any idea how to
construct aggregated statistics for an inheritance tree.
regards, tom lane