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[Edit this page](https://github.com/ClickHouse/ClickHouse/tree/master/docs/en/operations/system-tables/asynchronous_metrics.md)

Querying in ClickHouse Cloud

The data in this system table is held locally on each node in ClickHouse Cloud. Obtaining a complete view of all data, therefore, requires the `clusterAllReplicas` function. See [here](/docs/operations/system-tables/overview#system-tables-in-clickhouse-cloud) for further details.

Contains metrics that are calculated periodically in the background. For example, the amount of RAM in use.

Columns:

- `metric` ([String](/docs/sql-reference/data-types/string)) — Metric name.
- `value` ([Float64](/docs/sql-reference/data-types/float)) — Metric value.
- `description` ([String](/docs/sql-reference/data-types/string) - Metric description)

**Example**

```
SELECT * FROM system.asynchronous_metrics LIMIT 10
```

```
┌─metric──────────────────────────────────┬──────value─┬─description────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ AsynchronousMetricsCalculationTimeSpent │ 0.00179053 │ Time in seconds spent for calculation of asynchronous metrics (this is the overhead of asynchronous metrics).                                                                                                                                              │
│ NumberOfDetachedByUserParts             │          0 │ The total number of parts detached from MergeTree tables by users with the `ALTER TABLE DETACH` query (as opposed to unexpected, broken or ignored parts). The server does not care about detached parts and they can be removed.                          │
│ NumberOfDetachedParts                   │          0 │ The total number of parts detached from MergeTree tables. A part can be detached by a user with the `ALTER TABLE DETACH` query or by the server itself it the part is broken, unexpected or unneeded. The server does not care about detached parts and they can be removed. │
│ TotalRowsOfMergeTreeTables              │    2781309 │ Total amount of rows (records) stored in all tables of MergeTree family.                                                                                                                                                                                   │
│ TotalBytesOfMergeTreeTables             │    7741926 │ Total amount of bytes (compressed, including data and indices) stored in all tables of MergeTree family.                                                                                                                                                   │
│ NumberOfTables                          │         93 │ Total number of tables summed across the databases on the server, excluding the databases that cannot contain MergeTree tables. The excluded database engines are those who generate the set of tables on the fly, like `Lazy`, `MySQL`, `PostgreSQL`, `SQlite`. │
│ NumberOfDatabases                       │          6 │ Total number of databases on the server.                                                                                                                                                                                                                   │
│ MaxPartCountForPartition                │          6 │ Maximum number of parts per partition across all partitions of all tables of MergeTree family. Values larger than 300 indicates misconfiguration, overload, or massive data loading.                                                                       │
│ ReplicasSumMergesInQueue                │          0 │ Sum of merge operations in the queue (still to be applied) across Replicated tables.                                                                                                                                                                       │
│ ReplicasSumInsertsInQueue               │          0 │ Sum of INSERT operations in the queue (still to be replicated) across Replicated tables.                                                                                                                                                                   │
└─────────────────────────────────────────┴────────────┴────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
```

## Metric descriptions[​](#metric-descriptions "Direct link to Metric descriptions")

### AsynchronousHeavyMetricsCalculationTimeSpent[​](#asynchronousheavymetricscalculationtimespent "Direct link to AsynchronousHeavyMetricsCalculationTimeSpent")

Time in seconds spent for calculation of asynchronous heavy (tables related) metrics (this is the overhead of asynchronous metrics).

### AsynchronousHeavyMetricsUpdateInterval[​](#asynchronousheavymetricsupdateinterval "Direct link to AsynchronousHeavyMetricsUpdateInterval")

Heavy (tables related) metrics update interval

### AsynchronousMetricsCalculationTimeSpent[​](#asynchronousmetricscalculationtimespent "Direct link to AsynchronousMetricsCalculationTimeSpent")

Time in seconds spent for calculation of asynchronous metrics (this is the overhead of asynchronous metrics).

### AsynchronousMetricsUpdateInterval[​](#asynchronousmetricsupdateinterval "Direct link to AsynchronousMetricsUpdateInterval")

Metrics update interval

### BlockActiveTime\_*name*[​](#blockactivetime_name "Direct link to blockactivetime_name")

Time in seconds the block device had the IO requests queued. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. Source: `/sys/block`. See <https://www.kernel.org/doc/Documentation/block/stat.txt>

### BlockDiscardBytes\_*name*[​](#blockdiscardbytes_name "Direct link to blockdiscardbytes_name")

Number of discarded bytes on the block device. These operations are relevant for SSD. Discard operations are not used by ClickHouse, but can be used by other processes on the system. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. Source: `/sys/block`. See <https://www.kernel.org/doc/Documentation/block/stat.txt>

### BlockDiscardMerges\_*name*[​](#blockdiscardmerges_name "Direct link to blockdiscardmerges_name")

Number of discard operations requested from the block device and merged together by the OS IO scheduler. These operations are relevant for SSD. Discard operations are not used by ClickHouse, but can be used by other processes on the system. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. Source: `/sys/block`. See <https://www.kernel.org/doc/Documentation/block/stat.txt>

### BlockDiscardOps\_*name*[​](#blockdiscardops_name "Direct link to blockdiscardops_name")

Number of discard operations requested from the block device. These operations are relevant for SSD. Discard operations are not used by ClickHouse, but can be used by other processes on the system. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. Source: `/sys/block`. See <https://www.kernel.org/doc/Documentation/block/stat.txt>

### BlockDiscardTime\_*name*[​](#blockdiscardtime_name "Direct link to blockdiscardtime_name")

Time in seconds spend in discard operations requested from the block device, summed across all the operations. These operations are relevant for SSD. Discard operations are not used by ClickHouse, but can be used by other processes on the system. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. Source: `/sys/block`. See <https://www.kernel.org/doc/Documentation/block/stat.txt>

### BlockInFlightOps\_*name*[​](#blockinflightops_name "Direct link to blockinflightops_name")