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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 information about and status of [scheduling nodes](/docs/operations/workload-scheduling#hierarchy) residing on the local server.
This table can be used for monitoring. The table contains a row for every scheduling node.

Example:

```
SELECT *
FROM system.scheduler
WHERE resource = 'network_read' AND path = '/prio/fair/prod'
FORMAT Vertical
```

```
Row 1:
──────
resource:          network_read
path:              /prio/fair/prod
type:              fifo
weight:            5
priority:          0
is_active:         0
active_children:   0
dequeued_requests: 67
canceled_requests: 0
dequeued_cost:     4692272
canceled_cost:     0
busy_periods:      63
vruntime:          938454.1999999989
system_vruntime:   ᴺᵁᴸᴸ
queue_length:      0
queue_cost:        0
budget:            -60524
is_satisfied:      ᴺᵁᴸᴸ
inflight_requests: ᴺᵁᴸᴸ
inflight_cost:     ᴺᵁᴸᴸ
max_requests:      ᴺᵁᴸᴸ
max_cost:          ᴺᵁᴸᴸ
max_speed:         ᴺᵁᴸᴸ
max_burst:         ᴺᵁᴸᴸ
throttling_us:     ᴺᵁᴸᴸ
tokens:            ᴺᵁᴸᴸ
```

Columns:

- `resource` ([String](/docs/sql-reference/data-types)) — Resource name
- `path` ([String](/docs/sql-reference/data-types)) — Path to a scheduling node within this resource scheduling hierarchy
- `type` ([String](/docs/sql-reference/data-types)) — Type of a scheduling node.
- `weight` ([Float64](/docs/sql-reference/data-types)) — Weight of a node, used by a parent node of `fair` type.
- `priority` ([Int64](/docs/sql-reference/data-types)) — Priority of a node, used by a parent node of 'priority' type (Lower value means higher priority).
- `is_active` ([UInt8](/docs/sql-reference/data-types)) — Whether this node is currently active - has resource requests to be dequeued and constraints satisfied.
- `active_children` ([UInt64](/docs/sql-reference/data-types)) — The number of children in active state.
- `dequeued_requests` ([UInt64](/docs/sql-reference/data-types)) — The total number of resource requests dequeued from this node.
- `canceled_requests` ([UInt64](/docs/sql-reference/data-types)) — The total number of resource requests canceled from this node.
- `dequeued_cost` ([Int64](/docs/sql-reference/data-types)) — The sum of costs (e.g. size in bytes) of all requests dequeued from this node.
- `throughput` ([Float64](/docs/sql-reference/data-types)) — Current average throughput (dequeued cost per second).
- `canceled_cost` ([Int64](/docs/sql-reference/data-types)) — The sum of costs (e.g. size in bytes) of all requests canceled from this node.
- `busy_periods` ([UInt64](/docs/sql-reference/data-types)) — The total number of deactivations of this node.
- `vruntime` ([Nullable(Float64)](/docs/sql-reference/data-types)) — For children of `fair` nodes only. Virtual runtime of a node used by SFQ algorithm to select the next child to process in a max-min fair manner.
- `system_vruntime` ([Nullable(Float64)](/docs/sql-reference/data-types)) — For `fair` nodes only. Virtual runtime showing `vruntime` of the last processed resource request. Used during child activation as the new value of `vruntime`.
- `queue_length` ([Nullable(UInt64)](/docs/sql-reference/data-types)) — For `fifo` nodes only. Current number of resource requests residing in the queue.
- `queue_cost` ([Nullable(Int64)](/docs/sql-reference/data-types)) — For fifo nodes only. Sum of costs (e.g. size in bytes) of all requests residing in the queue.
- `budget` ([Nullable(Int64)](/docs/sql-reference/data-types)) — For fifo nodes only. The number of available 'cost units' for new resource requests. Can appear in case of discrepancy of estimated and real costs of resource requests (e.g. after read/write failure)
- `is_satisfied` ([Nullable(UInt8)](/docs/sql-reference/data-types)) — For constraint nodes only (e.g. `inflight_limit`). Equals to `1` if all the constraint of this node are satisfied.
- `inflight_requests` ([Nullable(Int64)](/docs/sql-reference/data-types)) — For `inflight_limit` nodes only. The number of resource requests dequeued from this node, that are currently in consumption state.
- `inflight_cost` ([Nullable(Int64)](/docs/sql-reference/data-types)) — For `inflight_limit` nodes only. The sum of costs (e.g. bytes) of all resource requests dequeued from this node, that are currently in consumption state.
- `max_requests` ([Nullable(Int64)](/docs/sql-reference/data-types)) — For `inflight_limit` nodes only. Upper limit for inflight\_requests leading to constraint violation.
- `max_cost` ([Nullable(Int64)](/docs/sql-reference/data-types)) — For `inflight_limit` nodes only. Upper limit for inflight\_cost leading to constraint violation.
- `max_speed` ([Nullable(Float64)](/docs/sql-reference/data-types)) — For `bandwidth_limit` nodes only. Upper limit for bandwidth in tokens per second.
- `max_burst` ([Nullable(Float64)](/docs/sql-reference/data-types)) — For `bandwidth_limit` nodes only. Upper limit for tokens available in token-bucket throttler.
- `throttling_us` ([Nullable(Int64)](/docs/sql-reference/data-types)) — For `bandwidth_limit` nodes only. Total number of microseconds this node was in throttling state.
- `tokens` ([Nullable(Float64)](/docs/sql-reference/data-types)) — For `bandwidth_limit` nodes only. Number of tokens currently available in token-bucket throttler.

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