Hi, On 2019-04-21 17:46:09 -0700, Peter Geoghegan wrote: > Andres has suggested that I work on teaching nbtree to accommodate > variable-width, logical table identifiers, such as those required for > indirect indexes, or clustered indexes, where secondary indexes must > use a logical primary key value instead of a heap TID.
I think it's two more cases: - table AMs that want to support tables that are bigger than 32TB. That used to be unrealistic, but it's not anymore. Especially when the need to VACUUM etc is largely removed / reduced. - global indexes (for cross-partition unique constraints and such), which need a partition identifier as part of the tid (or as part of the index key, but I think that actually makes interaction with indexam from other layers more complicated - the inside of the index maybe may want to represent it as a column, but to the outside that ought not to be visible) > Thoughts? Seems reasonable to me. I, more generally, wonder if there's not a case to squeeze out more padding than "just" what you describe (since we IIRC don't frequently keep pointers into such tuples anyway, and definitely don't for byval attrs). But that's very likely better done separately. Greetings, Andres Freund
