Re: cost-based vacuum

Ian Westmacott <ianw@intellivid.com> writes:
> If I make the single configuration change of setting
> vacuum_cost_delay=1000, each iteration in analyze_thread takes
> much longer, of course.  But what I also see is that the CPU
> usage of the connections for writer_thread and reader_thread
> spike up to well over 80% each (this is a dualie) and latency
> drops to 8-10s, during the ANALYZEs.

[ scratches head... ]  That doesn't make any sense at all.

> I don't understand why this would be.  I don't think there
> are any lock issues, and I don't see any obvious I/O issues.
> Am I missing something?  Is there any way to get some
> insight into what those connections are doing?

Profiling maybe?  Can you put together a self-contained test case
that replicates this behavior, so other people could look?

            regards, tom lane