On 8/27/13 7:58 AM, Robert Haas wrote:
 We have a *general* need to be able to throttle server-side resource
utilization, particularly I/O.  This is a problem not only for
pg_basebackup, but for COPY, CLUSTER, VACUUM, and even things like
UPDATE.  Of all of those, the only one for which we currently have any
kind of a solution is VACUUM.

I didn't mention it specifically, but I always presumed that the "Cost limited statements RFC" proposal I floated: http://www.postgresql.org/message-id/519ea5ff.5040...@2ndquadrant.com (and am still working on) would handle the base backup case too. pg_basebackup is just another client. Some sort of purpose made solution for pg_basebackup alone may be useful, but I'd be shocked if the sort of general mechanism I described there wasn't good enough to handle many of the backup limiting cases too.

Also, once that and the block write counters I also sent an RFC out for are in place, I have a plan for adding a server-wide throttling mechanism. I want to extract a cluster wide read and write rate and put a cluster wide limit on that whole thing. It seemed too hard to jump into without these other two pieces of plumbing in place first.

Greg Smith   2ndQuadrant US    g...@2ndquadrant.com   Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.com

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