But the problem in this case is probably this note: > This means that a REINDEX <https://www.postgresql.org/docs/12/sql-reindex.html> operation on an index pg_upgrade'd from a previous release could potentially fail.
You can't REINDEX safely regarding that note. pá 4. 10. 2019 v 16:06 odesílatel Laurenz Albe <laurenz.a...@cybertec.at> napsal: > On Fri, 2019-10-04 at 10:00 -0300, Marcelo Lacerda wrote: > > There are a few instances where the release notes seem to indicate > > that the administrator should use pg_dump to upgrade a database so > > that improvements on btree can be available. > > > > Here are they: > > > > 1. > > > > >In new btree indexes, the maximum index entry length is reduced by > > eight bytes, to improve handling of duplicate entries (Peter > > Geoghegan) > > > This means that a REINDEX operation on an index pg_upgrade'd from a > > previous release could potentially fail. > > > > > > 2. > > >Improve performance and space utilization of btree indexes with many > > duplicates (Peter Geoghegan, Heikki Linnakangas) > > >... > > >Indexes pg_upgrade'd from previous releases will not have these > > benefits. > > > > 3. > > >Allow multi-column btree indexes to be smaller (Peter Geoghegan, > > Heikki Linnakangas) > > >... > > >Indexes pg_upgrade'd from previous releases will not have these > > benefits. > > > > > > My questions are: > > > > 1. Is this a current limitation of pg_upgrade that will be dealt > > afterwards? > > > > 2. Are we going to see more of such cases were pg_upgrade leaves the > > database incompatible with newer features. > > > > 3. What's the recommendation for administrators with databases that > > are too large to be upgraded with pg_dump? > > pg_upgrade doesn't touch the index data, so it cannot rewrite indexes > to take advantage of these improvements. > > There is no incompatibility involved. > > You can always REINDEX some indexes later. > Now that we have REINDEX CONCURRENTLY, it shouldn't hurt as much. > > Yours, > Laurenz Albe > -- > Cybertec | https://www.cybertec-postgresql.com > > > >
