PostgreSQL replication monitoring
@pcarranza here if number of rows in result for pg_stat_replication_pg_xlog_location_diff
is not one, then alert about PG replication stopped. If there is 0 rows, then state!="streaming"
.
issues is here - https://gitlab.com/gitlab-com/infrastructure/issues/782.
PS: we can merge it as is, but in case we need to do more testing, like stop replication.