Re: Performance degradation of inserts when database size grows

Dne 23.5.2011 21:05, Robert Haas napsal(a):
> On Mon, May 23, 2011 at 2:46 PM, Tomas Vondra <tv@fuzzy.cz> wrote:
>> Really? He already has 64 checkpoint segments, which is about 1GB of
>> xlog data. The real problem is that the amount of buffers to write is
>> constantly growing. At the beginning there's 62861 buffers (500MB) and
>> at the end there's 137657 buffers (1GB).
>>
>> IMHO increasing the number of checkpoint segments would make this
>> disruption even worse.
>
> Maybe - but it would also make the checkpoints less frequent, which
> might be a good thing.
>
>> In 9.1 there's a feature that spreads checkpoint writes, but with 8.4
>> that's not possible.
>
> What feature are you referring to here?  Checkpoint spreading was
> added in 8.3, IIRC.

You're absolutely right, I was talking about

  checkpoint_completion_target

and it was added in 8.3. Your memory is obviously better than mine.

Tomas