sample.sql_in File Reference

SQL functions for random sampling. More...

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Functions
aggregate bigint	weighted_sample (bigint value, float8 weight)
	Sample a single row according to weights. More...

Detailed Description

See Also

For an overview of random-sampling functions, see the module description Random Sampling.

Definition in file sample.sql_in.

Function Documentation

aggregate bigint weighted_sample	(	bigint	value,
		float8	weight
	)

Parameters

value	Value of row. Uniqueness is not enforced. If a value occurs multiple times, the probability of sampling this value is proportional to the sum of its weights.
weight	Weight for row. A negative value here is treated has zero weight.

Returns

identifier of the selected row. The probability of sampling any particular row (value, weight) is weight/SUM(weight).

Definition at line 93 of file sample.sql_in.