"Jeffrey Baker" <jwbaker@gmail.com> writes:
> I increased it to 1GB, restarted the vacuum, and system performance
> seems the same. The root of the problem, that an entire CPU is in the
> iowait state and the storage device is doing random i/o, is unchanged:
Yeah, but you just reduced the number of index scans that will be needed
by a factor of 1GB/16MB. Hang in there ...
regards, tom lane