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Query Execution Modes (Broker vs Historical)

hbutani edited this page Aug 2, 2016 · 3 revisions

Broker Mode

This is the default mode. In this case the DruidQuery is executed against the Broker. The DruidRDD is setup with a Partition for each Query Interval.

Historical Mode

This is turned on by setting the queryHistoricalServer parameter. In this case a DruidRDD Partition is setup for each Historical Server. When there are multiple Historical Servers that are serving a Segment, Segment assignment is made to the Historical Server that is handling the fewest segments. In this we try to spread the load is spread across Historical servers.

Not supported Queries

Currently this mode is not available when the Query contains

  • A Sort/Limit Specification
  • A Having Filter
  • Any JavaScript Aggregations
  • Any Post Aggregation Specifications
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