One our customer complains that he spawned two `create index
concurrently` for two different tables and both stuck in"waiting for old
snapshots".
I wonder if two CIC can really block each other in `WaitForOlderSnapshots`?
I found the similar question in hacker archive:
https://www.postgresql.org/message-id/flat/MWHPR20MB1421AEC7CEC67B159AC188F6A19A0%40MWHPR20MB1421.namprd20.prod.outlook.com
<https://www.postgresql.org/message-id/flat/MWHPR20MB1421AEC7CEC67B159AC188F6A19A0%40MWHPR20MB1421.namprd20.prod.outlook.com>
but it is quite old (2016). Was the problem fixed since that time? And
if not, why there it is not mentioned in CIC documentation that
performing several CIC in parallel can cause "deadlock"?
Thanks in advance,
Konstantin
