Sorry for delay,
I wonder if the prioritisation could be done
using nice - each backend is a separate
process, so why not to do 'nice(10)' for low
priority processes or something like that.
Yes, to a limited degree you can prioritise
queries using nice and ionice, but it's awkward because:
- All queries run as `postgres' so you can't do per-user limiting very easily
- The postmaster doesn't have a way to set the
nice level and ionice level when it forks a
backend, nor does the backend have any way to do
it later. You can use your own user-defined C functions for this, though.
Postmaster hasn't a way to modify the system nice
or ionice, but it can send signals to child
process. Sending a user signal to sleep
completely the child (i/o and cpu) or before any
i/o call can do the trick. Perhaps it's time to
add a query scheduler or a more complete/complex one in postgres.
--
Craig Ringer
----------------------------------------------
Si la vida te da la espalda, ¡tocale el culo!
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