Stephen Frost <sfr...@snowman.net> writes: > * Tom Lane (t...@sss.pgh.pa.us) wrote: >> Why is it that we need to lock a table at all if we're just going to dump >> its ACL?
> I think I'm coming around to agree with that, but it seems like it'd be > better to look at each component and say "we know X is safe, so we won't > lock the table if we're only doing X" rather than saying "we only need to > lock the table for case X". Agreed. I did not realize you'd broken down the aspects of an object so finely in pg_dump, but since you have, this is a good way to approach it. > When considering the components: > - DEFINITION > - DATA > [ obviously need lock ] > - COMMENT > Shouldn't require a lock, only uses a relatively simple query against > pg_description. > - SECLABEL > Similar to COMMENT, shouldn't require a lock. > - ACL > ACL info is collected from pg_class relacl without any server-side > functions being used which would impact the result. > - POLICY > Uses pg_get_expr(), which at least gets the relation name from > SysCache, so we'll want to lock the table. > - USERMAP > Uses pg_options_to_table(), but I don't think that actually uses > SysCache at all, it's just taking the array provided and builds a > table out of it, so I think this case is ok. USERMAP seems a bit squishy and easily broken, perhaps. Not sure there's an advantage to distinguishing this case --- why did you break it out from DEFINITION to start with? Also, AFAICS, it does not apply to tables which are the only things we lock anyway. Seems reasonable otherwise. > Of course, the pg_dump would still end up including the ACLs for > pg_authid and whatever other tables the user has changed the ACLs on and > errors will be thrown during restore if the restore is done with a > non-superuser. Right, but at least you have the option of ignoring such errors. regards, tom lane -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers