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> I'm curious how much query planners have to make tradeoffs between effective optimizations and not overloading the analysis phase. In case of PostgreSQL: con
by anarazel 9y ago
> I'm curious how much query planners have to make tradeoffs between effective optimizations and not overloading the analysis phase.
In case of PostgreSQL: constantly. Pretty much every planner improvement has to argue that it's not likely to unduly increase plan time.
- kuschku 9y agoWhat about pre-compiling plans? With server-side prepared statements it would make sense to use entirely different planning time tradeoffs.
- anarazel 9y agoIt's not that simple. Server side prepared statements are used to great effect in OLTPish scenarios too. A serviceable approach would be to perform additional optimizations based on the query's cost - but that's hard to do without incurring a complete replan, because of the bottom up dynamic programming approach of a good chunk of the planning.
- kuschku 9y agoWell, I’d love to see a way to set such a query planning cost target. There’s a few statements which I never change, but run thousands of times a day, and which are extremely expensive.