On Fri, 2019-11-08 at 15:04 +1300, Thomas Munro wrote: > So we have three proposals: > > 1. Assume that pre-13 indexes that depend on collations are > potentially corrupted and complain until they are reindexed. This > could be done by having pg_upgrade run ALTER INDEX ... DEPENDS ON > COLLATION "fr_FR" VERSION '' (empty string, or some other default > value that we don't think is going to coincide with a real version). > 2. Assume that pre-13 indexes are not corrupted. In the target 13 > database, the index will be created in the catalogs with the > provider's current version. > 3. We don't know if pre-13 indexes are corrupted or not, and we'll > record that with a special value just as in proposal #1, except that > we could show a different hint for that special version value. It > would tell you can you can either REINDEX, or run ALTER INDEX ... > DEPENDS ON COLLATION "fr_FR" VERSION '34.0' if you believe the index > to have been created with the current collation version on an older > release of PostgreSQL that didn't track versions.
I think #1 is bad because it would frighten all users, even those who didn't upgrade their libc at all, only PostgreSQL. I don't think that shouting "wolf" for no real reason will improve trust in PostgreSQL. #2 is bad because it may hide pre-existing index corruption. #3 is the best proposal, but there is still the need to run ALTER INDEX on all affected indexes to keep PostgreSQL from nagging. Perhaps the situation could be improved with a pg_upgrade option --i-know-my-indexes-are-fine that causes a result like #2. Together with a bold note in the release notes, this may relieve the pain. Yours, Laurenz Albe
