On Fri, Jul 17, 2020 at 11:26:56AM -0400, Tom Lane wrote: > Magnus Hagander <mag...@hagander.net> writes: > > As Amit mentions it is also triggered by some store parameter changes. But > > not all. So looking at it the other way, the part that the end user really > > cares about it "which ALTER TABLE operations will rewrite the table and > > which will not". Maybe what we need is a section specifically on this that > > summarizes all the different ways that it can happen. > > No, what we need is EXPLAIN for DDL ;-). Trying to keep such > documentation in sync with the actual code behavior would be impossible. > (For one thing, some aspects can be affected by extension datatype > behaviors.)
I know Tom put a wink on that, but I actually do feel that the only clean way to do this is to give users a way to issue the query in a non-executing way that will report if a rewrite is going to happen. -- Bruce Momjian <br...@momjian.us> https://momjian.us EnterpriseDB https://enterprisedb.com The usefulness of a cup is in its emptiness, Bruce Lee
