On 12/7/15 10:44 AM, Simon Riggs wrote:
> There are many optimizations we might adopt, yet planning time is a
> factor. It seems simple enough to ignore more complex optimizations if
> we have already achieved a threshold cost (say 10). Such a test would
> add nearly zero time for the common case. We can apply the optimizations
> in some kind of ordering depending upon the cost, so we are careful to
> balance the cost/benefit of trying certain optimizations.
Unfortunately I've seen a lot of millisecond queries that have 6 figure
estimates, due to data being in cache. So I'm not sure how practical
that would be.
Maybe a better starting point would be a planner timeout.
I definitely agree we need some method to limit planning time when
necessary (ie: OLTP). Without that we'll never be able to start testing
more complex optimizations.
--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
Data in Trouble? Get it in Treble! http://BlueTreble.com
