[Bizgres-general] Performance - WAL bypass + parse

[Mark Kirkwood]

Decided to check this out after seeing the message on -hackers,
very nice, more speed is always good!

One thing I am wondering about - what do you see if you load files 
bigger than the RAM size of the machine (e.g. 4G in your case)? Does the 
performance difference still persist? I am raising this because:

i) It is a more realistic DW scenario
ii) 146M is only 6x the disk cache of 3 drives (assuming 8M for each)
iii) You dont get much chance to measure the impact of the bgwriter or
checkpointer (speed may be throttled on these?)

If you guys have not got the time to do some experiments along these
lines, I could look into it, however I don't have such flash HW ... :-).

Cheers

Mark


>---------------------------------------------------------------------------
>  Case:  1 column table, 146MB load, TEXT field
>---------------------------------------------------------------------------
>Fast Parsing in copy, fsync = false
>  21MB/s
>
>Fast Parsing in copy, WAL Bypass enabled
>  27.6MB/s
>
>WAL Bypass enabled (No fast parse)
>  14.2MB/s
>
>WAL Bypass disabled, fsync = true
>  11.2MB/s
>
>WAL Bypass disabled, fsync = false (same as baseline)
>  12.1MB/s