Re: generic plans and "initial" pruning

On Mon, Nov 17, 2025 at 9:50 PM Amit Langote <amitlangote09@gmail.com> wrote:
> On Wed, Nov 12, 2025 at 11:17 PM Amit Langote <amitlangote09@gmail.com> wrote:
> > * Enable pruning-aware locking in cached / generic plan reuse (0004):
> > extends GetCachedPlan() and CheckCachedPlan() to call ExecutorPrep()
> > on each PlannedStmt in the CachedPlan, locking only surviving
> > partitions. Adds CachedPlanPrepData to pass this through plan cache
> > APIs and down to execution via QueryDesc. Also reinstates the
> > firstResultRel locking rule added in 28317de72 but later lost due to
> > revert of the earlier pruning patch, to ensure correctness when all
> > target partitions are pruned.
>
> Looking at the changes to executor/function.c, I also noticed that I
> had mistakenly allocated the ExecutorPrep state in
> SQLFunctionCache.fcontext whereas the correct context for execution
> related state is SQLFunctionCache.subcontext.  In the updated patch,
> I've made postquel_start() reparent the prep EState's es_query_cxt to
> subcontext from fcontext. I also did not have a test case that
> exercised cached plan reuse for SQL functions, so I added one. I split
> the function.c's GetCachedPlan() + CachedPlanPrepData plumbing into a
> new patch 0005 so it can be reviewed separately, since it is the only
> non-mechanical call-site change.

I also noticed a bug in the prep cleanup logic that runs when a cached
plan becomes invalid during the prep phase. Patch 0005 fixes that and
adds a regression test that exercises the invalidation path. This will
be folded into 0004 later.