Ian Knopke <knopke@music.mcgill.ca> writes:
> Comparing the beginning and end times from the log, it seems to take the
> same amount of time to insert at the beginning of the process as after
> about twenty minutes. However, I also logged the input from vmstat, which
> shows the amount of memory available shrinking rapidly.
AFAICT you are just showing us kernel disk cache expanding to fill
unused memory. This is normal and not a cause for alarm.
> Eventually the system moves to using swap and things really slow down.
Disk cache can't cause swapping --- the kernel will just throw away
cached pages when the memory is needed for something else. It could
be that you have growth in the number of Postgres processes, or the
sizes of individual processes, but vmstat isn't very helpful for
determining that (good ol' top would be more useful). In any case
you haven't actually shown us any data from the state where the system
is slow, so it's a bit hard to conjecture about what's going on.
Some other important information that you haven't let us in on is the
platform and the Postgres version you're using.
regards, tom lane
