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Segment Pruning When Querying

Starting from Kylin 5.0, we support the calculation of the dimension value range (maximum and minimum) of all dimensions when building the Segment, so we can prune segment during queries, reducing the scanning range of the segment to optimize some query performance.

Configuration​

This optimization is enable by default. Under normal circumstances, you do not need to pay attention to this optimization. In some extreme cases, system-level or project-level shutdown is supported.

To disable it on the system level, configure the parameters in $KYLIN_HOME/conf/kylin.properties . To disable it on project level, add the configuration in Setting -> Advanced Settings -> Custom Project Configuration.

kylin.storage.columnar.dimension-range-filter-enabled=false

Known Limitation​

  1. Currently, only the query filter conditions including =, in, >, >=, <, <=, and, or support pruning segment. Filters including not, is null are not supported.

  2. This optimization will slightly increase the building time, but it is basically negligible compared to the total building time.

  3. The historical data that has been built will not use this optimization. If you want the historical data to apply this optimization, you need to refresh the Segment.

  4. The multi-level partition models are not supported.