Re: BUG #19686: Rolling back SET TABLESPACE

Hi Manu,

v6 looks good to me. The child CHECK case, VALIDATE CONSTRAINT and
sql_drop all leave 0 stale entries now. One small thing.

ATSetTableSpaceCopyIndexes() also runs for ALTER INDEX, so a plain
ALTER INDEX SET TABLESPACE in a pipeline now commits on its own.
Maybe only call it for tables and matviews.

I recently got interested in replication lag with physical
replication, so I also looked at the replay side on a standby.

A plain top-level ALTER costs the same as master. In a transaction
block it costs more.

WAL size. The index copy is logged page by page, so the extra WAL
is the size of the indexes. Given they are mostly FPI, I think it is okay
for
replicas to quickly catch up.

AccessExclusiveLock. Each index now gets one too, so one more lock
record per index goes to the standby. I think that is okay. The
table already has that lock, and queries lock the table before its
indexes, so nobody new is blocked.

Thanks,
Shihao