On 3/11/18 14:25, Andres Freund wrote:
>> It's perhaps a bit confusing that some of the jit_* settings take effect
>> at plan time and some at execution time. At the moment, this mainly
>> affects me reading the code ;-), but it would also have some effect on
>> prepared statements and such.
> Not quite sure what you mean?
I haven't tested this, but what appears to be the case is that
SET jit_above_cost = 0;
PREPARE foo AS SELECT ....;
SET jit_above_cost = infinity;
EXECUTE foo;
will use JIT, because jit_above_cost applies at plan time, whereas
SET jit_expressions = on;
PREPARE foo AS SELECT ....;
SET jit_expressions = off;
EXECUTE foo;
will *not* use JIT, becaue jit_expressions applies at execution time.
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
