Background: in the past postgresql had some settings that openacs needed in order to function properly. As of postgres-9.0.0 final, released today, two are gone and one is going shortly, for a total of 3 out of 3.
TIP #147: alter openacs so it doesn't need to have missing from clauses supplied. Reasoning: this option is gone in pg9.
TIP #148: alter openacs so it uses "advanced" flavor regexps rather than "extended", OR find out how to set extended flavor in each individual regexp. Reasoning: this option is gone in pg9.
TIP #149: alter openacs so it no longer depends on oids. Reasoning: While removal of this option may have been forgotten for pg-9.0.0, an email has been sent to postgres-hackers mailing list reminding them to remove this option.