On Fri, Aug 28, 2026 at 4:21 PM Robert Haas <[email protected]> wrote: > > > > ### 5. pg_plan_advice.advice / stash advice changes are silently ignored by > > an already-cached generic plan > > This is a planner control feature; it does not affect behavior other > than at plan time. I don't see that as a bug. That said, I think it > would be perfectly valid for someone to try to figure a way for advice > stash changes to invalidate plans, but I suspect that will require > significant new infrastructure. Plan invalidation is generally tied to > catalog modifications, and here we would instead want to tie it to a > plan ID. We could do that by adding a custom invalidation type to > sinval.h just for the use of pg_stash_advice, but would be a pretty > serious piece of core infrastructure for an as-yet-unproven contrib > module to use to solve a problem which (for all we know now) may have > little practical impact.
FWIW, this was already discussed back in the day I think in [1]. I wouldn't remeber it otherwise if not the mailing list, but apparently ANALYZE on the table affected was enough to trigger the change [2]. Perhaps adding one statement to the docs would be good enough to cover it for now, like: "In order to change the already cached plans, issue ANALYZE on relevant tables." (because apparently without it it now confused 2 people and 1 AI ;)) -J. [1] - https://www.postgresql.org/message-id/CA%2BTgmoYO0qtqz%2BV7S4q0e_dLhLrrsMxA51t5wks_y8Skv6cdRQ%40mail.gmail.com [2] - https://www.postgresql.org/message-id/CA%2BTgmob8O4TbZVr2zoqm5m-Zp6fj-8iBh%3D0u-xfiy5Xr5MNFCQ%40mail.gmail.com
