Thank you John. > you can upgrade to 9.0.18 painlessly. 9.1 or .2 or .3, not quite so > painless. What's the best way to get to 9.0.18, as a start? Is there a simple single command I can use? I'm on CentOS 6, 64bit. > have you tried a vacuum full of the whole cluster, with your applications > shut down? Not yet, not with the apps shut down entirely, but in read mode, yes. No new rows being added. SELECTs have to work as it's a high traffic website. > you will need to either pg_dumpall your old database 'cluster' and load this > into the new version, or use pg_upgrade, which is a fair bit trickier but > can do an in-place upgrade. if your databases aren't much over a few > dozen gigabytes, pg_dumpall is probably simpler than pg_upgrade. if your > databases are large, pg_dumpall -> psql restore may take a LONG time, so the > pg_upgrade process may be more efficient. Dread to use pg_upgrade after that confirmation of my fears. Our DB is around 200 GB. Even with pg_upgrade, will I have to once again tinker with all the conf files and authentication (which is md5 right now), change my passwords and do "template1" database stuff again? I saw the doc page on the postgresql.org site for pg_upgrade, but it presumes a lot of things in terms of knowledge. I just have one database "instance" or "cluster". The 10-15 tables are not complex. But they're large, as in over a billion rows now. All I need is for the upgrade to happen automatically, retaining my config and paths and whatnot (or clear instructions that work, step by step). Thanks!