> On 23 Mar 2026, at 22:58, Merlin Moncure <[email protected]> wrote:
> On Thu, Mar 19, 2026 at 1:09 AM Andrei Lepikhov <[email protected]> wrote:
> Poking around more, I see that the bad plans are related to bloat. A simple
> REINDEX of one of the indexes made the problem disappear; however, what's odd
> is that the estimates didn't really change although the net plan cost
> certainly did. It's also worth noting ANALYZE doesn't help, only REINDEX
> does.
We already have plan-freezing and plan-hinting extensions. If I understand you
correctly, it makes sense to invent a statistics-freezing module right now. I
think such a module will be quite simple - is it a good crutch for you?
Also, we have some stuff already to work out your case someday:
1. Postgres already scans indexes during planning to improve estimations of
inequality clauses (get_actual_variable_range). Here may be a way to estimate
the bloat effect. Not sure how to do it, but allowing index AM to read the page
number of the returned tuple, you might, in principle, detect anomalies in the
index.
2. We are quite close to vacuum statistics and detailed index statistics. This
is also a way to estimate issues of stale statistics/bloated indexes and decide
on the scan type.
So, keep the community posted and provide more real-life examples to build up a
proper solution.
Andrei,
pgEdge
