"refresh was aborted because of conflicts caused by deferred txns"
*Cause: There are outstanding conflicts logged in the DefError table
at the materialized view's master.
*Action: Resolve the conflicts in the master DefError table and
refresh again after the table is empty. Alternatively,
refresh with refresh_after_errors set to TRUE, which
will proceed with the refresh even if there are conflicts
in the master's DefError table. Proceeding despite conflicts
can result with an updatable materialized view's changes appearing
to be temporarily lost (until a refresh succeeds after the
conflicts are resolved).