Re: [HACKERS] performance test

Michael Meskes wrote:
>
> I tried inserting 15000 tuples each in two tables via pgsql and timed it.
> After insertion I also created btree indeces on both tables.
>
...
>
> Then I switched to 6.5 without -F:
> real 2m35.833s
> user 0m2.900s
> sys 0m3.910s
>
...
>
> Then I switched on -F:
> real 1m11.573s
> user 0m3.150s
> sys 0m3.760s
>
> I've seen even bigger advantages of -F.

You've seen disadvantages of our unperfect buffer manager -:)
When server need in buffer for new data comming and there is
no unused buffers in pool (i.e. - all buffers filled with new
data and marked as dirty), server gets some dirty buffer,
writes it AND FSYNC file. So, server does many fsyncs
even with BEGIN/END while should do _one_ fsync at COMMIT.

Having this problem fixed you wouldn't had so big difference
between -F and BEGIN/END-no-F.

Vadim