On 1/11/15 3:57 PM, Robert Haas wrote:
On Sun, Jan 11, 2015 at 5:27 AM, Stephen Frost <sfr...@snowman.net> wrote:
* Robert Haas (robertmh...@gmail.com) wrote:
On Thu, Jan 8, 2015 at 2:46 PM, Stephen Frost <sfr...@snowman.net> wrote:
Yeah, if we come up with a plan for X workers and end up not being able
to spawn that many then I could see that being worth a warning or notice
or something. Not sure what EXPLAIN has to do anything with it..
That seems mighty odd to me. If there are 8 background worker
processes available, and you allow each session to use at most 4, then
when there are >2 sessions trying to do parallelism at the same time,
they might not all get their workers. Emitting a notice for that
seems like it would be awfully chatty.
Yeah, agreed, it could get quite noisy. Did you have another thought
for how to address the concern raised? Specifically, that you might not
get as many workers as you thought you would?
I'm not sure why that's a condition in need of special reporting.
The case raised before (that I think is valid) is: what if you have a query
that is massively parallel. You expect it to get 60 cores on the server and
take 10 minutes. Instead it gets 10 and takes an hour (or worse, 1 and takes 10
hours).
Maybe it's not worth dealing with that in the first version, but I expect it
will come up very quickly. We better make sure we're not painting ourselves in
a corner.
--
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com
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