tuple_difference_theta_double function

Applies to: check marked yes Databricks Runtime 18.2 and above

Computes the set difference (A minus B) of a TupleSketch with double summaries and a Theta Sketch. The returned sketch contains only keys that appear in the TupleSketch but not in the Theta Sketch.

Syntax

tuple_difference_theta_double ( first, second )

Arguments

Returns

A BINARY value containing the TupleSketch representing the set difference (A - B).

If first or second is NULL, the result is NULL.

Notes

  • Argument order is fixed: first must be a TupleSketch and second must be a Theta Sketch. Passing the sketch types in the reverse order raises TUPLE_INVALID_INPUT_SKETCH_BUFFER_FAMILY.
  • Summary values from the TupleSketch are preserved for keys in the result.
  • This function is not the same as tuple_sketch_theta_double, which returns the sampling rate of a TupleSketch.

Common error conditions

Examples

> SELECT tuple_sketch_estimate_double(
    tuple_difference_theta_double(
      tuple_sketch_agg_double(col1, val1),
      theta_sketch_agg(col2)
    )
  ) FROM VALUES (5, 5.0D, 4), (1, 1.0D, 4), (2, 2.0D, 5), (3, 3.0D, 1) tab(col1, val1, col2);
2.0
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