Bruce Momjian <pgman@candle.pha.pa.us> writes:
> That certainly would make sense. We have hesitated to gather more
> statistics because of the time involved. Fuller statistics on just the
> indexed columns could be a big win and be done fairly quickly because
> the rows are already sorted in the index.
Yeah, a scan over just the index itself would be a perfect way to
gather stats. The normal objection to it (can't tell whether entries
correspond to currently-valid tuples) doesn't apply, because we don't
really care whether the stats are perfectly accurate.
Should put this in TODO, along with something about splitting the
ANALYZE function out of VACUUM and making it invokable as a separate
statement.
regards, tom lane