Robert Haas wrote: > On Tue, Jan 4, 2011 at 4:49 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > > Robert Haas <robertmh...@gmail.com> writes: > >> On Tue, Jan 4, 2011 at 4:09 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > >>> * Existing GIN indexes are upwards compatible so far as on-disk storage > >>> goes, but they will of course be missing entries for empty, null, or > >>> null-containing items. ?Users who want to do searches that should find > >>> such items will need to reindex after updating to 9.1. > > > >> This is the only part of this proposal that bothers me a little bit. > >> It would be nice if the system could determine whether a GIN index is > >> "upgraded from 9.0 or earlier and thus doesn't contain these entries" > >> - and avoid trying to use the index for these sorts of queries in > >> cases where it might return wrong answers. > > > > I don't think it's really worth the trouble. ?The GIN code has been > > broken for these types of queries since day one, and yet we've had only > > maybe half a dozen complaints about it. ?Moreover there's no practical > > way to "avoid trying to use the index", since in many cases the fact > > that a query requires a full-index scan isn't determinable at plan time. > > > > The best we could really do is throw an error at indexscan start, and > > that doesn't seem all that helpful. ?But it probably wouldn't take much > > code either, if you're satisfied with that answer. ?(I'm envisioning > > adding a version ID to the GIN metapage and then checking that before > > proceeding with a full-index scan.) > > I'd be satisfied with that answer. It at least makes it a lot more > clear when you've got a problem. If this were a more common scenario, > I'd probably advocate for a better solution, but the one you propose > seems adequate given the frequency of the problem as you describe it.
What does pg_upgrade need to do about this for 9.1? Just tell people they might get an GIN error someday? -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
