Re: [DOC] Document concurrent index builds waiting on each other

On Sat, Sep 28, 2019 at 10:22:28PM -0300, Alvaro Herrera wrote:
> I always thought that create index concurrently was prevented from
> running concurrently in a table by the ShareUpdateExclusive lock that's
> held during the operation.

REINDEX CONCURRENTLY and CIC can deadlock while waiting for each other
to finish after their validation phase, see:
https://www.postgresql.org/message-id/20190507030756.GD1499@paquier.xyz
https://www.postgresql.org/message-id/20190507032543.GH1499@paquier.xyz
--
Michael