distributed_plan_* session settings

These settings are available in system.settings and are autogenerated from source.

distributed_plan_default_reader_bucket_count

Default number of tasks for parallel reading in distributed query. Tasks are spread across between replicas. Used by the rule-based distributed planner. The cost-based optimizer chooses the read fan-out by estimated cost and does not use this setting.

distributed_plan_default_shuffle_join_bucket_count

Default number of buckets for distributed shuffle-hash-join. Used by the rule-based distributed planner. The cost-based optimizer chooses the fan-out by estimated cost and does not use this setting.

distributed_plan_execute_locally

Run all tasks of a distributed query plan locally. Useful for testing and debugging.

distributed_plan_force_exchange_kind

Force specified kind of Exchange operators between distributed query stages.

Possible values:

• ‘’ - do not force any kind of Exchange operators, let the optimizer choose,
• ‘Persisted’ - use temporary files in object storage,
• ‘Streaming’ - stream exchange data over network.

distributed_plan_force_shuffle_aggregation

Use Shuffle aggregation strategy instead of PartialAggregation + Merge in distributed query plan.

distributed_plan_max_rows_to_broadcast

Maximum rows to use broadcast join instead of shuffle join in distributed query plan. A heuristic for the rule-based distributed planner. When the cost-based optimizer is enabled, the broadcast-vs-shuffle choice is made by estimated cost and this setting has no effect.

distributed_plan_optimize_exchanges

Removes unnecessary exchanges in distributed query plan. Disable it for debugging.

distributed_plan_prefer_replicas_over_workers

Serialize the distributed query plan for execution at replicas.

distributed_plan_workers_num

How many stateless workers will be used to execute this query. Zero disables stateless-worker leasing for distributed plans.

distributed_plan_workers_provisioning_timeout_ms

Total wall-clock time, in milliseconds, a query may spend provisioning stateless workers before execution: leasing them from the discovery service and verifying they are reachable. The query blocks up to this budget for the leased workers to become ready; when it elapses the query proceeds with the workers verified so far, or fails if none became available. Zero waits only for the initial lease-and-verify pass (no retries).