"Tom Lane" <[EMAIL PROTECTED]> writes:
> I'm not sure offhand whether the existing correlation stats would be of use
> for
> it, or whether we'd have to get ANALYZE to gather additional data.
Please forgive the tangent, but would it be practical to add support for
gathering statistics on an arbitrary expression associated with a table, rather
than just on materialized columns? For example:
analyze my_tab for expression 'my_func(my_tab.col)' ;
It seems like any time you'd consider using a functional index, this feature
would let the planner calculate decent selectivity estimates for the
expression's otherwise opaque data distribution. The expression might be
treated as a virtual column on the table; not sure if that helps or hurts.
Should I post this question on pgsql-hackers?
--
Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance
