Re: HashAgg degenerate case

On Wed, 2024-11-06 at 15:50 +1300, David Rowley wrote:
> I don't think it could be that exactly though as that could lead to
> JIT compilation over and over again from the following chain of
> function calls: build_hash_tables() -> build_hash_table() ->
> BuildTupleHashTableExt() -> ExecBuildGroupingEqual() ->
> ExecReadyExpr() -> jit_compile_expr()

New patch attached. It extends ResetTupleHashTable() so that the caller
can force setting a new nbuckets, which recreates the tuplehash_hash.

agg_refill_hash_table() now uses that to recalculate and set the
nbuckets for the current grouping set's hashtab, and frees the hashtab
for all other grouping sets (it "frees" them by setting to a minimal
size bucket array).

Regards,
Jeff Davis