Re: ANALYZE sampling is too good

On Mon, Dec 9, 2013 at 8:45 PM, Heikki Linnakangas
<hlinnakangas@vmware.com> wrote:
> Claudio Freire <klaussfreire@gmail.com> wrote:
>>On Mon, Dec 9, 2013 at 8:14 PM, Heikki Linnakangas
>><hlinnakangas@vmware.com> wrote:
>>> I took a stab at using posix_fadvise() in ANALYZE. It turned out to
>>be very
>>> easy, patch attached. Your mileage may vary, but I'm seeing a nice
>>gain from
>>> this on my laptop. Taking a 30000 page sample of a table with 717717
>>pages
>>> (ie. slightly larger than RAM), ANALYZE takes about 6 seconds without
>>the
>>> patch, and less than a second with the patch, with
>>> effective_io_concurrency=10. If anyone with a good test data set
>>loaded
>>> would like to test this and post some numbers, that would be great.
>>
>>Kernel version?
>
> 3.12, from Debian experimental. With an ssd drive and btrfs filesystem.  Admittedly not your average database server
setup,so it would be nice to get more reports from others.
 


Yeah, read-ahead isn't relevant for SSD.