On 2019-Apr-11, Michael Paquier wrote: > > I was going to just remove the caveat, but then I discovered that > > REINDEX CONCURRENTLY doesn't work on INVALID indexes (why?). > > This is a wanted choice. The index built in parallel of the existing > one during a concurrent reindex is marked invalid during most of the > operation. Hence, if the reindex is interrupted or fails, you finish > with potentially twice the number of original indexes, half being > invalid and the other half being the ones in use. If the user decides > to rinse and repeat the concurrent reindex, and if we were to also > select invalid indexes for the operation, then you would finish by > potentially doing twice the amount of work when working on a relation, > half of it for nothing.
Hmm, I suppose that makes sense for REINDEX TABLE or anything that reindexes more than one index, but if you do REINDEX INDEX surely it is reasonable to allow the case? -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
