On 4/21/15 4:07 PM, Peter Eisentraut wrote:
> On 4/21/15 4:45 PM, Jim Nasby wrote:
> In order for a background worker to keep up with some of the workloads
> that have been presented as counterexamples, you'd need multiple
> background workers operating in parallel and preferring to work on
> certain parts of a table. That would require a lot more sophisticated
> job management than we currently have for, say, autovacuum.
My thought was that the foreground queries would send page IDs to the
bgworker via a shmq. If the queries have to do much waiting at all on IO
then I'd expect the bgworker to be able to keep pace with a bunch of
them since it's just grabbing buffers that are already in the pool (and
only those in the pool; it wouldn't make sense for it to pull it back
from the kernel, let alone disk).
We'd need to code this so that if a queue fills up the query doesn't
block; we just skip that opportunity to prune. I think that'd be fine.
--
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com
