Release 0.157

General Changes

Fix regression that could cause queries containing scalar subqueries to fail during planning.
Reduce CPU usage of coordinator in large, heavily loaded clusters.
Add support for DESCRIBE OUTPUT.
Add bitwise_and_agg() and bitwise_or_agg() aggregation functions.
Add JMX stats for the scheduler.
Add query.min-schedule-split-batch-size config flag to set the minimum number of splits to consider for scheduling per batch.
Remove support for scheduling multiple tasks in the same stage on a single worker.
Rename node-scheduler.max-pending-splits-per-node-per-stage to node-scheduler.max-pending-splits-per-task. The old name may still be used, but is deprecated and will be removed in a future version.

Fail attempts to create tables that are bucketed on non-existent columns.
Improve error message when trying to query tables that are bucketed on non-existent columns.
Add support for processing partitions whose schema does not match the table schema.
Add support for creating external Hive tables using the external_location table property.