DISTINCTCOUNTSMARTHLL
This section contains reference documentation for the DISTINCT_COUNT_SMART_HLL function.
Signature
DISTINCT_COUNT_SMART_HLL(col[, params])
col
(required): Name of the column to aggregate on.params
(optional): Semicolon-separated parameter key-value pairs:threshold
: The threshold to convert the value set into a HyperLogLog (default 100_000).log2m
: log2m for the HyperLogLog (default 12).
Example:
DISTINCT_COUNT_SMART_HLL(col, 'threshold=10000;log2m=8')
Usage Examples
These examples are based on the Batch Quick Start.
DISTINCTCOUNTSMARTHLL considerations
DISTINCTCOUNTHLL()
is faster thanDISTINCTCOUNT()
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 asDISTINCTCOUNT()
because the serialized HLL size is larger than sending individual values.DISTINCTCOUNTHLLPLUS()
provides more precise results thanDISTINCTCOUNTHLL()
with the same performance.DISTINCTCOUNTSMARTHLL()
automatically shifts to HLL when reaching a threshold, and comes with some overhead.
Last updated
Was this helpful?