On 2018-02-13 13:43:40 -0500, Robert Haas wrote: > On Sun, Feb 11, 2018 at 10:00 AM, Merlin Moncure <mmonc...@gmail.com> wrote: > > I tested several queries in my application that had >30 second compile > > times against a one second run time,. Not being able to manage when > > compilation happens is making it difficult to get a sense of llvm > > performance in the general case. > > In theory, the GUCs Andres has added to only compile if the estimated > total cost is above some threshold is supposed to help with this.
Note that the GUCs as posted are set *way* too low, they're currently toy thresholds. That's easier for testing, but I guess I should set them to something better. It's not unrealistic to expect them to be insufficient however - the overhead roughly linearly grows with the number of expressions, which might not reflect the gain equally. > How did you manage to create an expression that took 30 seconds to > compile? It doesn't take that long to compile a 5000-line C file. Any chance a debug build of LLVM was used? The overhead of that are easily an order of magnitude or more. Greetings, Andres Freund
