3 ms·

Now that CTEs are no longer optimization fences in recent versions of Postgres, is there a way to somehow manually declare an optimization fence around a certai

Now that CTEs are no longer optimization fences in recent versions of Postgres, is there a way to somehow manually declare an optimization fence around a certain region of the query? I've had similar problems in Snowflake with the query planner taking a bad path, and no obvious way to hint otherwise.

bhaak 3y ago
Functions are hard barriers for optimization and I don't see that changing any time soon. Which goes even so far that EXPLAIN doesn't work on them and you just get a black box of "Function call to ..." in the execution plan. Using auto_explain is the only workaround known to me for that.
- emilsedgh 3y ago
  But that's not the case when functions are inlined.
  - bhaak 3y ago
    Interesting. I've never seen this though. I guess that only happens for simple cases?
baq 3y ago
WITH MATERIALIZED restores the fence.