On Wed, 10 Jul 2024 at 22:58, Tomas Vondra <tomas.von...@enterprisedb.com> wrote: > IIRC long time ago VACUUM FULL actually worked in a similar way, i.e. by > moving rows around. I'm not sure if it did the lock-free thing as > proposed here (probably not), but I guess at least some of the reasons > why it was replaced by CLUSTER would still apply to this new thing.
Yeah, that changed in 9.0. The old version still obtained an AEL on the table. I think the primary issue with the old way was index bloat wasn't fixed. The release notes for 9.0 do claim the CLUSTER method "is substantially faster in most cases", however, I imagine there are plenty of cases where it wouldn't be. e.g, it's hard to imagine rewriting the entire 1TB table and indexes is cheaper than moving 1 row out of place row. David
