On Wed, Jun 24, 2020 at 07:38:43AM -0500, Justin Pryzby wrote: > On Wed, Jun 24, 2020 at 05:06:28AM -0400, Bruce Momjian wrote: > > It would seem merge join has almost the same complexities as the new > > hash join code, since it can spill to disk doing sorts for merge joins, > > and adjusting work_mem is the only way to control that spill to disk. I > > don't remember anyone complaining about spills to disk during merge > > join, so I am unclear why we would need a such control for hash join. > > It loooks like merge join was new in 8.3. I don't think that's a good > analogy, > since the old behavior was still available with enable_mergejoin=off.
Uh, we don't gurantee backward compatibility in the optimizer. You can turn off hashagg if you want. That doesn't get you to PG 13 behavior, but we don't gurantee that. -- Bruce Momjian <br...@momjian.us> https://momjian.us EnterpriseDB https://enterprisedb.com The usefulness of a cup is in its emptiness, Bruce Lee
