Re: Enable data checksums by default

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