""John Top-k apad"" <topkapad@gmail.com> wrote
>
> from pg_stast_get_blocks_fetched i can see that both queries need almost
the
> same number of disk fetches which is quite reasonable ( the index is
> unclustered).
>
> But as you can see there is a great variation between query
> runtimes.Cansomeone explain this differnce?
>
Can you give a self-contained example (including what you did to clear the
file system cache (maybe unmount?) to *not* let the 2nd query to use the
file content from the 1st query)?
Regards,
Qingqing