# system.replication_queue {#system_tables-replication_queue} 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 the task in the queue. - `node_name` ([String](../../sql-reference/data-types/string.md)) — Node name in ZooKeeper. - `type` ([String](../../sql-reference/data-types/string.md)) — Type of the task in the queue: `GET_PARTS`, `MERGE_PARTS`, `DETACH_PARTS`, `DROP_PARTS`, or `MUTATE_PARTS`. - `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)) — The number of replicas waiting for the task to complete with confirmation of completion. This column is only relevant for the `GET_PARTS` task. - `source_replica` ([String](../../sql-reference/data-types/string.md)) — Name of the source replica. - `new_part_name` ([String](../../sql-reference/data-types/string.md)) — Name of the 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)) — The flag indicates whether the `DETACH_PARTS` task is in the queue. - `is_currently_executing` ([UInt8](../../sql-reference/data-types/int-uint.md)) — The flag indicates whether a specific task is being performed right now. - `num_tries` ([UInt32](../../sql-reference/data-types/int-uint.md)) — The number of failed attempts to complete the task. - `last_exception` ([String](../../sql-reference/data-types/string.md)) — Text message about the last error that occurred (if any). - `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)) — The number of postponed tasks. - `postpone_reason` ([String](../../sql-reference/data-types/string.md)) — The 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 the current merge. Empty if it's a mutation. **Example** ``` sql SELECT * FROM system.replication_queue LIMIT 1 FORMAT Vertical; ``` ``` text Row 1: ────── database: merge table: visits_v2 replica_name: mtgiga001-1t.metrika.yandex.net position: 15 node_name: queue-0009325559 type: MERGE_PARTS create_time: 2020-12-07 14:04:21 required_quorum: 0 source_replica: mtgiga001-1t.metrika.yandex.net new_part_name: 20201130_121373_121384_2 parts_to_merge: ['20201130_121373_121378_1','20201130_121379_121379_0','20201130_121380_121380_0','20201130_121381_121381_0','20201130_121382_121382_0','20201130_121383_121383_0','20201130_121384_121384_0'] is_detach: 0 is_currently_executing: 0 num_tries: 36 last_exception: Code: 226, e.displayText() = DB::Exception: Marks file '/opt/clickhouse/data/merge/visits_v2/tmp_fetch_20201130_121373_121384_2/CounterID.mrk' doesn't exist (version 20.8.7.15 (official build)) last_attempt_time: 2020-12-08 17:35:54 num_postponed: 0 postpone_reason: last_postpone_time: 1970-01-01 03:00:00 ``` **See Also** - [Managing ReplicatedMergeTree Tables](../../sql-reference/statements/system.md/#query-language-system-replicated) [Original article](https://clickhouse.tech/docs/en/operations/system_tables/replication_queue)