I've got a sql language function which does a fairly simple select from a
table. If I give it one value, it performs quickly (half a ms). If I give it
another value, it does not (1.1 seconds). When I run the equivalent select
outside of the function, both values perform roughly the same (even though one
value returns 140k more rows, as expected).
My understanding is that this generally happens because the plan should be
different for the different values, but the first time the function is run it
caches the plan for one of the values and will never use the appropriate plan
for the second value. However, when I do an explain analyze of the raw sql for
both values, I get the same plan. So my understanding must be wrong?
I suppose the other possibility is that the slower value is slower in a
function because it's returning 140k more rows and the function has to deal
with that additional data. but that seems far-fetched, given that each row
is just an int.
--
Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance
