Am Dienstag, den 26.03.2019, 16:14 +0100 schrieb Christoph Berg:
> select 92551.0/97363;
> 0.9506
>
> So the cost is 5% in this very contrived case. In almost any other
> setting, the cost would be lower, I'd think.
Well, my machine (Intel(R) Core(TM) i7-6770HQ CPU @ 2.60GHz, 32 GByte
RAM) tells me this:
pgbench -s 50 -i pgbench
pg_ctl -o "--shared-buffers=128kB" restart
pgbench -r -P4 -Mprepared -T60 -c $clients -j $clients -n -S
...prewarm...
Clients checksums
1 20110
2 35338
4 67207
8 96627
16 110091
Clients no checksums
1 21716
2 38543
4 72118
8 117545
16 121415
Clients Impact
1 0,926045312212194
2 0,916846119918014
4 0,931903269641421
8 0,822042621974563
16 0,906733105464728
So between ~7% to 18% impact with checksums in this specific case here.
Bernd
