On Tue, Jul 9, 2019 at 2:19 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Given the purposes of this test, I think it'd be reasonable to force
> both enable_hashjoin = on and enable_mergejoin = off at the very top
> of the join_hash script, or the corresponding place in join.sql in
> v11. Thomas, was there a specific reason for forcing enable_mergejoin
> = off for only some of these tests?
Based on a suggestion from Andres (if I recall correctly), I wrapped
each individual test in savepoint/rollback, and then set just the GUCs
needed to get the plan shape and execution code path I wanted to
exercise, and I guess I found that I only needed to disable merge
joins for some of them. The idea was that the individual tests could
be understood independently.
--
Thomas Munro
https://enterprisedb.com