Query management properties#

query.client.timeout#

Configures how long the cluster runs without contact from the client application, such as the CLI, before it abandons and cancels its work.

query.execution-policy#

  • Type: string

  • Default value: phased

  • Session property: execution_policy

Configures the algorithm to organize the processing of all of the stages of a query. You can use the following execution policies:

  • phased schedules stages in a sequence to avoid blockages because of inter-stage dependencies. This policy maximizes cluster resource utilization and provides the lowest query wall time.

  • all-at-once schedules all of the stages of a query at one time. As a result, cluster resource utilization is initially high, but inter-stage dependencies typically prevent full processing and cause longer queue times which increases the query wall time overall.

query.max-hash-partition-count#

  • Type: integer

  • Default value: 100

  • Session property: max_hash_partition_count

The maximum number of partitions to use for processing distributed operations, such as joins, aggregations, partitioned window functions and others.

query.min-hash-partition-count#

  • Type: integer

  • Default value: 4

  • Session property: min_hash_partition_count

The minimum number of partitions to use for processing distributed operations, such as joins, aggregations, partitioned window functions and others.

query.max-writer-tasks-count#

  • Type: integer

  • Default value: 100

  • Session property: max_writer_tasks_count

The maximum number of tasks that will take part in writing data during INSERT, CREATE TABLE AS SELECT and EXECUTE queries. The limit is only applicable when redistribute-writes or scale-writers is be enabled.

query.low-memory-killer.policy#

  • Type: string

  • Default value: total-reservation-on-blocked-nodes

Configures the behavior to handle killing running queries in the event of low memory availability. Supports the following values:

  • none - Do not kill any queries in the event of low memory.

  • total-reservation - Kill the query currently using the most total memory.

  • total-reservation-on-blocked-nodes - Kill the query currently using the most memory specifically on nodes that are now out of memory.

Note

Only applies for queries with task level retries disabled (retry-policy set to NONE or QUERY)

task.low-memory-killer.policy#

  • Type: string

  • Default value: total-reservation-on-blocked-nodes

Configures the behavior to handle killing running tasks in the event of low memory availability. Supports the following values:

  • none - Do not kill any tasks in the event of low memory.

  • total-reservation-on-blocked-nodes - Kill the tasks which are part of the queries which has task retries enabled and are currently using the most memory specifically on nodes that are now out of memory.

  • least-waste - Kill the tasks which are part of the queries which has task retries enabled and use significant amount of memory on nodes which are now out of memory. This policy avoids killing tasks which are already executing for a long time, so significant amount of work is not wasted.

Note

Only applies for queries with task level retries enabled (retry-policy=TASK)

query.low-memory-killer.delay#

The amount of time a query is allowed to recover between running out of memory and being killed, if query.low-memory-killer.policy or task.low-memory-killer.policy is set to value differnt than none.

query.max-execution-time#

  • Type: duration

  • Default value: 100d

  • Session property: query_max_execution_time

The maximum allowed time for a query to be actively executing on the cluster, before it is terminated. Compared to the run time below, execution time does not include analysis, query planning or wait times in a queue.

query.max-length#

  • Type: integer

  • Default value: 1,000,000

  • Maximum value: 1,000,000,000

The maximum number of characters allowed for the SQL query text. Longer queries are not processed, and terminated with error QUERY_TEXT_TOO_LARGE.

query.max-planning-time#

  • Type: duration

  • Default value: 10m

  • Session property: query_max_planning_time

The maximum allowed time for a query to be actively planning the execution. After this period the coordinator will make its best effort to stop the query. Note that some operations in planning phase are not easily cancellable and may not terminate immediately.

query.max-run-time#

  • Type: duration

  • Default value: 100d

  • Session property: query_max_run_time

The maximum allowed time for a query to be processed on the cluster, before it is terminated. The time includes time for analysis and planning, but also time spend in a queue waiting, so essentially this is the time allowed for a query to exist since creation.

query.max-scan-physical-bytes#

  • Type: data size

  • Session property: query_max_scan_physical_bytes

The maximum number of bytes that can be scanned by a query during its execution. When this limit is reached, query processing is terminated to prevent excessive resource usage.

query.max-stage-count#

  • Type: integer

  • Default value: 150

  • Minimum value: 1

The maximum number of stages allowed to be generated per query. If a query generates more stages than this it will get killed with error QUERY_HAS_TOO_MANY_STAGES.

Warning

Setting this to a high value can cause queries with large number of stages to introduce instability in the cluster causing unrelated queries to get killed with REMOTE_TASK_ERROR and the message Max requests queued per destination exceeded for HttpDestination ...

query.max-history#

The maximum number of queries to keep in the query history to provide statistics and other information. If this amount is reached, queries are removed based on age.

query.min-expire-age#

The minimal age of a query in the history before it is expired. An expired query is removed from the query history buffer and no longer available in the Web UI.

query.remote-task.enable-adaptive-request-size#

  • Type: boolean

  • Default value: true

  • Session property: query_remote_task_enable_adaptive_request_size

Enables dynamically splitting up server requests sent by tasks, which can prevent out-of-memory errors for large schemas. The default settings are optimized for typical usage and should only be modified by advanced users working with extremely large tables.

query.remote-task.guaranteed-splits-per-task#

  • Type: integer

  • Default value: 3

  • Session property: query_remote_task_guaranteed_splits_per_task

The minimum number of splits that should be assigned to each remote task to ensure that each task has a minimum amount of work to perform. Requires query.remote-task.enable-adaptive-request-size to be enabled.

query.remote-task.max-error-duration#

Timeout value for remote tasks that fail to communicate with the coordinator. If the coordinator is unable to receive updates from a remote task before this value is reached, the coordinator treats the task as failed.

query.remote-task.max-request-size#

  • Type: data size

  • Default value: 8MB

  • Session property: query_remote_task_max_request_size

The maximum size of a single request made by a remote task. Requires query.remote-task.enable-adaptive-request-size to be enabled.

query.remote-task.request-size-headroom#

  • Type: data size

  • Default value: 2MB

  • Session property: query_remote_task_request_size_headroom

Determines the amount of headroom that should be allocated beyond the size of the request data. Requires query.remote-task.enable-adaptive-request-size to be enabled.

retry-policy#

  • Type: string

  • Default value: NONE

The retry policy to use for Fault-tolerant execution. Supports the following values:

  • NONE - Disable fault-tolerant execution.

  • TASK - Retry individual tasks within a query in the event of failure. Requires configuration of an exchange manager.

  • QUERY - Retry the whole query in the event of failure.