OK. Will do another round of testing. -----Original Message----- From: David Rowley <dgrowleyml@xxxxxxxxx> Sent: Thursday, July 22, 2021 00:44 To: ldh@xxxxxxxxxxxxxxxxxx Cc: Tom Lane <tgl@xxxxxxxxxxxxx>; Peter Geoghegan <pg@xxxxxxx>; Justin Pryzby <pryzby@xxxxxxxxxxxxx>; pgsql-performance@xxxxxxxxxxxxxx Subject: Re: Big performance slowdown from 11.2 to 13.3 On Thu, 22 Jul 2021 at 16:37, ldh@xxxxxxxxxxxxxxxxxx <ldh@xxxxxxxxxxxxxxxxxx> wrote: > Seems like no cigar ☹ See plan pasted below. I changed the conf as follows: > - hash_mem_multiplier = '2' > - work_mem = '1GB' > Batches: 5 Memory Usage: 2400305kB Disk Usage: 126560kB You might want to keep going higher with hash_mem_multiplier until you see no "Disk Usage" there. As mentioned, v11 didn't spill to disk and just used all the memory it pleased. That was a bit dangerous as it could result in OOM, so it was fixed. David
