I got an error installing OpenACS 5.2 on a server equipped with an old PostgreSQL 7.3.

Fortunately it was easy enogh to fix it. The file to fix is acs-relationships-create.sql (package acs-kernel) where the line:

create sequence acs_data_links_seq start with 1;

should read instead:

create sequence acs_data_links_seq start 1;

because the optional 'with' is not recognized by PostgreSQL 7.3