On Mon, Oct 31, 2022 at 1:33 PM Michael Paquier <michael@paquier.xyz> wrote:
On Mon, Oct 31, 2022 at 01:12:09PM +0800, Richard Guo wrote: > BTW, I noticed a micro-optimization opportunity in examine_variable that > we can fetch the RangeTblEntry for 'onerel' outside the foreach loop > when iterating the extended stats so that we can do it only once rather > than for each stat.
Isn't that the kind of thing where we'd better have some regression coverage?
Yeah, we need to have some regression tests for that. I come up with a case in stats_ext like below
CREATE STATISTICS stxdinp ON (a + 1), a, b FROM stxdinp; SELECT * FROM check_estimated_rows('SELECT a + 1, b FROM ONLY stxdinp GROUP BY 1, 2');
This case should be able to cover both expression stats and ndistinct stats. Hence, attach v2 patch.
