"sundayjiang(蒋浩天)" <sundayjiang@tencent.com> writes: > > The purpose of this patch is to prevent replacing a function via `CREATE OR REPLACE FUNCTION` with a new definition that is not marked as `IMMUTABLE`, if the existing function is referenced by an index expression. > > > > Replacing such functions may lead to index corruption or runtime semantic inconsistencies, especially when the function’s output is not stable for the same input.
TBH, I find this proposal to be useless nannyism. Replacing a function that is used in an index is problematic if you change its behavior (that is, its actual output for given inputs) in any way. Whether it's marked IMMUTABLE is a very minor side point.
Isn't preventing a dump-restore hazard sufficient reason to do this? The now-volatile function will be dumped as such and the create index during the restore will fail because of that.
