We have been using Postgres 9.5.12 behind PGBouncer and facing some weird
issues. Whenever we running long running DDL statements (e.g. 'add index
concurently' or 'Alter table alter column type'), after some time, we start
seeing that almost every query in our application starts getting blocked.
I understand that the operations I mentioned cab be unsafe, but the queries
being blocked are on completely unrelated tables. I used the instructions
given on Postgres wiki (https://wiki.postgresql.org/wiki/Lock_Monitoring)
to correlate the blocking and blocked statements and there seems to be
absolutely no correlation.
Thanks,
Ashu