Contains information about tasks from replication queues stored in Zookeeper for tables in the `ReplicatedMergeTree` family.
Columns:
-`database` ([String](../../sql-reference/data-types/string.md)) — Name of the database.
-`table` ([String](../../sql-reference/data-types/string.md)) — Name of the table.
-`replica_name` ([String](../../sql-reference/data-types/string.md)) — Replica name in ZooKeeper. Different replicas of the same table have different names.
-`position` ([UInt32](../../sql-reference/data-types/int-uint.md)) — Position of task in the queue.
-`type` ([String](../../sql-reference/data-types/string.md)) — Type of task in the queue.
-`create_time` ([Datetime](../../sql-reference/data-types/datetime.md)) — Date and time when the task was submitted for execution.
-`required_quorum` ([UInt32](../../sql-reference/data-types/int-uint.md)) — Number of replicas waiting for the task to complete with confirmation of completion. This column is only relevant for the `GET PART` task.
-`source_replica` ([String](../../sql-reference/data-types/string.md)) — Name of source replica.
-`new_part_name` ([String](../../sql-reference/data-types/string.md)) — Name of new part.
-`parts_to_merge` ([Array](../../sql-reference/data-types/array.md) ([String](../../sql-reference/data-types/string.md))) — Names of parts to merge or update.
-`is_detach` ([UInt8](../../sql-reference/data-types/int-uint.md)) — Flag indicates whether the task is being performed using the `TO DETACHED` expression.
-`is_currently_executing` ([UInt8](../../sql-reference/data-types/int-uint.md)) — Flag indicates whether a specific task is being performed right now.
-`num_tries` ([UInt32](../../sql-reference/data-types/int-uint.md)) — Number of failed attempts to complete the task.
-`last_exception` ([String](../../sql-reference/data-types/string.md)) — Text of the message about the last task execution error.
-`last_attempt_time` ([Datetime](../../sql-reference/data-types/datetime.md)) — Date and time when the task was last attempted.
-`num_postponed` ([UInt32](../../sql-reference/data-types/int-uint.md)) — Number of postponed tasks.
-`postpone_reason` ([String](../../sql-reference/data-types/string.md)) — Reason why the task was postponed.
-`last_postpone_time` ([Datetime](../../sql-reference/data-types/datetime.md)) — Date and time when the task was last postponed.
-`merge_type` ([String](../../sql-reference/data-types/string.md)) — Type of current merge. Empty if it's an mutation.
**Example**
``` sql
SELECT * FROM system.replication_queue LIMIT 1 FORMAT Vertical;