David Rowley <david.row...@2ndquadrant.com> writes:
> On Thu, 20 Dec 2018 at 17:50, Tom Lane <t...@sss.pgh.pa.us> wrote:
>> Hm, are you thinking of making BITS_PER_BITMAPWORD match sizeof(Pointer)
>> or something like that? That seems like a good compromise from here.
> Yeah, something along those lines. I've implemented that in the attached.
Pushed with some fiddling with the comment.
I wasn't excited about the test case you offered --- on HEAD, it pretty
much all devolves to file access operations (probably, checking the
current length of all the child relations). Instead I experimented
with an old test case I had for a complex-to-plan query, and got these
results:
HEAD, asserts off:
pgbench reports:
latency average = 11704.992 ms
tps = 0.085434 (including connections establishing)
tps = 0.085437 (excluding connections establishing)
Top hits according to perf:
+ 65.42% 65.16% 158499 postmaster postgres
[.] match_eclasses_to_foreign_key_col
+ 6.85% 6.82% 16634 postmaster postgres
[.] bms_overlap
+ 6.25% 6.22% 15173 postmaster postgres
[.] generate_join_implied_equalities_for_ecs
+ 3.91% 3.88% 9465 postmaster postgres
[.] make_canonical_pathkey
+ 3.04% 3.01% 7351 postmaster postgres
[.] have_relevant_eclass_joinclause
+ 2.06% 2.05% 4992 postmaster postgres
[.] bms_is_subset
+ 1.19% 1.18% 2887 postmaster postgres
[.] equal
+ 0.95% 0.95% 2309 postmaster postgres
[.] get_eclass_for_sort_expr
+ 0.90% 0.90% 2189 postmaster postgres
[.] add_paths_to_joinrel
With patch:
latency average = 10741.595 ms
tps = 0.093096 (including connections establishing)
tps = 0.093099 (excluding connections establishing)
+ 69.03% 68.76% 178278 postmaster postgres
[.] match_eclasses_to_foreign_key_col
+ 5.85% 5.82% 15138 postmaster postgres
[.] generate_join_implied_equalities_for_ecs
+ 4.58% 4.55% 11842 postmaster postgres
[.] bms_overlap
+ 4.38% 4.36% 11338 postmaster postgres
[.] make_canonical_pathkey
+ 2.77% 2.75% 7155 postmaster postgres
[.] have_relevant_eclass_joinclause
+ 1.30% 1.29% 3364 postmaster postgres
[.] equal
+ 1.26% 1.25% 3261 postmaster postgres
[.] bms_is_subset
+ 1.06% 1.05% 2722 postmaster postgres
[.] get_eclass_for_sort_expr
+ 0.70% 0.70% 1813 postmaster postgres
[.] add_paths_to_joinrel
Ignoring the, um, elephant in the room, this shows a pretty clear win
for the performance of bms_overlap and bms_is_subset, confirming
the thesis that this change is worthwhile.
I'll start a separate thread about match_eclasses_to_foreign_key_col.
regards, tom lane
