Hi, Here's two WIP patches that fixes the regression for me. The first part is from [1], so make large batches work, 0002 just creates a copy of the tupledesc to not cause issues in resource owner, 0003 ensures we only initialize the slots once (not per batch).
With the patches applied, the timings look like this: batch timing ---------------------- 1 64194.942 ms 10 7233.785 ms 100 2244.255 ms 32k 1372.175 ms which seems fine. I still need to get this properly tested etc. and make sure nothing is left over. regards [1] https://postgr.es/m/OS0PR01MB571603973C0AC2874AD6BF2594299%40OS0PR01MB5716.jpnprd01.prod.outlook.com -- Tomas Vondra EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company