I'm surprised to see that it's only Memoize that ever makes use of lateral_vars. I'd need a bit more time to process your patch, but one additional thought I had was that I wonder if the following code is still needed in nodeMemoize.c
if (bms_nonempty_difference(outerPlan->chgParam, node->keyparamids)) cache_purge_all(node);
Ideally, that would be an Assert failure, but possibly we should probably still call cache_purge_all(node) after Assert(false) so that at least we'd not start returning wrong results if we've happened to miss other cache keys. I thought maybe something like:
Hmm, I think this code is still needed because the parameter contained in the subplan below a Memoize node may come from parent plan, as in the test query added in 411137a42.
EXPLAIN (COSTS OFF) SELECT unique1 FROM tenk1 t0 WHERE unique1 < 3 AND EXISTS ( SELECT 1 FROM tenk1 t1 INNER JOIN tenk1 t2 ON t1.unique1 = t2.hundred WHERE t0.ten = t1.twenty AND t0.two <> t2.four OFFSET 0); QUERY PLAN ---------------------------------------------------------------- Index Scan using tenk1_unique1 on tenk1 t0 Index Cond: (unique1 < 3) Filter: (SubPlan 1) SubPlan 1 -> Nested Loop -> Index Scan using tenk1_hundred on tenk1 t2 Filter: (t0.two <> four) -> Memoize Cache Key: t2.hundred Cache Mode: logical -> Index Scan using tenk1_unique1 on tenk1 t1 Index Cond: (unique1 = t2.hundred) Filter: (t0.ten = twenty) (13 rows)
Currently we don't have a way to add Params of uplevel vars to Memoize cache keys. So I think we still need to call cache_purge_all() each time uplevel Params change.
