If I have a set of tables and I set their primary keys all to the same sequence, as in create sequence common_seq; create table alpha ( ID integer primary key default nextval('common_seq), other_field text ); create table beta ( ID integer primary key default nextval('common_seq), other_field real ); create table gamma ( ID integer primary key default nextval('common_seq), other_field oid ); Would this guarantee that each value of ID in any row of any of the tables would be unique amongst all of them? Would I get the same effect by creating a table like this: create table common ( ID serial primary key ); and then having alpha, beta and gamma inherit from it? -- Bruce ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly