Starburst optimizer properties#

SEP includes additional configuration and session properties to configure the included extensions of the optimizer.

Configuration properties on this page are set as follows:

Carefully monitor the impacts of changes of these expert-level configurations. The following properties can be configured:


  • Type: integer

  • Default value: 1000000

  • Session property: join_partitioned_build_min_row_count

Set the minimum number of rows required on the build side of a join to partition the table. Because partitioning of join hash table incurs overhead when processing the probe side data of the join data during query runtime, setting this property allows SEP to skip partitioning for tables too small to benefit from parallel hash table construction. Build side hash tables for joins can be either a single unpartitioned table or partitioned into the number of buckets defined by task_concurrency.


  • Type: boolean

  • Default value: true

  • Session property: pre_aggregate_case_aggregations

Enable pre-aggregation of CASE statements that contain multiple, similar CASE statements. Disabling this causes performance degradation in most cases. Only disable the feature if you have a very specific, technical need to do so, and only until that need is resolved.


  • Type: boolean

  • Default value: true

  • Session property: accelerated_repartitioning_enabled

Use the accelerated operator for repartitioning data across worker nodes to increase parallel query processing performance that require repartitioning.