DISTINCTCOUNTSMARTHLL

This section contains reference documentation for the DISTINCTCOUNTHLL function.

Signature

DISTINCTCOUNTSMARTHLL(colName, log2m)

Usage Examples

These examples are based on the Batch Quick Start.

DISTINCTCOUNTSMARTHLL considerations

  • DISTINCTCOUNTHLL()is faster than DISTINCTCOUNT()if data is pre-aggregated at ingestion or aggregated at a server with enough records. This performance improvement increases when comparing large datasets.

  • If very few records are pre-aggregated, DISTINCTCOUNTHLL()will not be as fast as DISTINCTCOUNT()because the serialized HLL size is larger than sending individual values.

  • DISTINCTCOUNTHLLPLUS()provides more precise results than DISTINCTCOUNTHLL()with the same performance.

  • DISTINCTCOUNTSMARTHLL()automatically shifts to HLL when reaching a threshold, and comes with some overhead.

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