On Thu, Nov 30, 2017 at 4:13 PM, Tom Lane <[email protected]> wrote: > Andres Freund <[email protected]> writes: >> Add some regression tests that exercise hash join code. > > At least one buildfarm member doesn't like this ...
$$); initially_multibatch | increased_batches ----------------------+------------------- ! t | f (1 row) rollback to settings; --- 6002,6008 ---- $$); initially_multibatch | increased_batches ----------------------+------------------- ! | (1 row) Hmm. aholehole didn't give me the hash join EXPLAIN ANALYZE output. All other animals are fine so far. Gah. My guess is that this is the following unlikely sequence: 1. Worker launched. 2. Leader descheduled. 3. Worker runs whole join. 4. Leader awakes from slumber, begins running plan and tries to scan outer relation, sees EOF, takes empty-outer optimisation and skips building hash table. 5. Explain has no data. It's arguably a bug that EXPLAIN ANALYZE can fail to give you what you asked for because of details of timing and I have a patch in development to fix that but it's not yet baked. Hmm. Wondering if there is a quick way to avoid that case in the meantime... -- Thomas Munro http://www.enterprisedb.com
