Re: WIP: Avoid creation of the free space map for small tables

Hi John Naylor,
On Tue, Jan 8, 2019 at 2:27 AM John Naylor <jcnaylor(at)gmail(dot)com> wrote:
> I've attached two patches for testing. Each one applies on top of the
> current patch.

Thanks for the patch, I did a quick test for both of the patches same
tests as in [1], now for fillfactors 20, 70, 100 (Note for
HEAP_FSM_CREATION_THRESHOLD = 4 highest tid inserted was 20 fillfactor
is (3,43), for 70 fillfactor is (3, 157) and for 100 fillfactor is
(3, 225), so exactly 4 pages are used)

Machine : cthulhu, same as before [2] and server settings is default.
Test: COPY command as in [1], for 500 tables.

Fill factor 20
execution time in ms %increase in
execution time
Base 119.238
v11-all-pages 121.974 2.2945705228
v11-Every-other-page 114.455 -4.0113051209
v11-last-page 113.573 -4.7510021973

Fill factor 70
execution time in ms %increase in execution time
Base 209.991
v11-all-pages 211.076 0.5166888105
v11-Every-other-page 206.476 -1.6738812616
v11-last-page 203.591 -3.0477496655

Fill factor 100
execution time in ms %increase in execution time
Base 269.691
v11-all-pages 270.078 0.1434975583
v11-Every-other-page 262.691 -2.5955630703
v11-last-page 260.293 -3.4847288193

Observations
1. Execution time of both base and v11-all-pages patch has improved
than my earlier results [2]. But still v11-all-pages is slightly
behind base.
2. v11-Every-other-page and v11-last-page patches improve the
performance from base.
3. IMHO v11-Every-other-page would be ideal to consider it improves
the performance and also to an extent avoid expansion if space is
already available.

[1] https://www.postgresql.org/message-id/CAJVSVGX%3D2Q52fwijD9cjeq1UdiYGXns2_9WAPFf%3DE8cwbFCDvQ%40mail.gmail.com
[2] https://www.postgresql.org/message-id/CAD__Ouj%3Dat4hy2wYidK90v92qSRLjU%2BQe4y-PwfjLLeGkhc6ZA%40mail.gmail.com

--
Thanks and Regards
Mithun Chicklore Yogendra
EnterpriseDB: http://www.enterprisedb.com