Re: JIT compiling with LLVM v9.0

On Sun, Feb 11, 2018 at 10:00 AM, Merlin Moncure <mmoncure(at)gmail(dot)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. But
if the compile time and the cost don't correlate, then we've got
trouble. 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.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company