Hi, On 2018-06-13 09:18:21 +0900, Michael Paquier wrote: > We map pg_wal_lsn_diff result to a numeric, so that could make sense to > use numeric as well here, which is not the greatest choice by the way as > that's an int64 internally, but that's more portable for any > (unlikely-to-happen) future changes. The reason to not use int64 is that it's signed. lsns are unsigned. Therefore you couldn't represent all LSNs without wrapping into negative. Greetings, Andres Freund