On Thu, Oct 14, 2021 at 12:48 AM Simon Riggs <simon.ri...@enterprisedb.com> wrote: > The hash index tuples are 20-bytes each. If that were rounded up to > 8-byte alignment, then that would be 24 bytes. > > Using pageinspect, the max(live_items) on any data page (bucket or > overflow) is 407 items, so they can't be 24 bytes long.
That's the same as an nbtree page, which confirms my suspicion. The 20 bytes consists of a 16 byte tuple, plus a 4 byte line pointer. The tuple-level alignment overhead gets you from 12 bytes to 16 bytes with a single int4 column. So the padding is there for the taking. -- Peter Geoghegan
