Relational Data - Aggregate Functions - Reference - Uniqthetasketch

From FojiSoft Docs

Calculates the approximate number of different argument values, using the Theta Sketch Framework. 

uniqTheta(x[, ...])

Arguments

The function takes a variable number of parameters. Parameters can be Tuple, Array, Date, DateTime, String, or numeric types.

Returned value

Implementation details

Function:

  • Calculates a hash for all parameters in the aggregate, then uses it in calculations.

  • Uses the KMV algorithm to approximate the number of different argument values.

      4096(2^12) 64-bit sketch are used. The size of the state is about 41 KB.

  • The relative error is 3.125% (95% confidence), see the relative error table for detail.

See Also

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