Sunday, September 7, 2008

Re: [HACKERS] reducing statistics write overhead

Martin Pihlak <> writes:
> I had also previously experimented with stat() based polling but ran into
> the same issues - no portable high resolution timestamp on files. I guess
> stat() is unusable unless we can live with 1 second update interval for the
> stats (eg. backend reads the file if it is within 1 second of the request).

> One alternative is to include a timestamp in the stats file header - the
> backend can then wait on that -- check the timestamp, sleep, resend the
> request, loop. Not particularly elegant, but easy to implement. Would this
> be acceptable?

Timestamp within the file is certainly better than trying to rely on
filesystem timestamps. I doubt 1 sec resolution is good enough, and
I'd also be worried about issues like clock skew between the
postmaster's time and the filesystem's time.

regards, tom lane

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