sample

Syntax

1sample(percentage-size-of-dataset) repeatable(seed)

sample

Required. Specifies the percentage of the dataset that is returned as a random sample. The percentage size value can be any positive decimal.

repeatable

Optional. To create a random sample deterministically, specify a seed. sample returns the same subset of data each time you pass repeatable the same seed value. The seed value can be any positive integer.

Usage

Use sample to project a query on a representative sample from your dataset, where each data point has an equal probability of being selected. sample runs pre-projection.

Add sample and repeatable after the load statement. Any operation performed on the query after the load statement affects only the random sample of data. Let’s look at an example.

1q = load "Opportunity" sample(10) repeatable(1);
2q = group q by all;
3q = foreach q generate count() as 'count';
4q = limit q 2000;

Here, the query returns the row count of the sample, 453—around 10% of the dataset's 4.6k rows. The repeatable keyword guarantees that the query always returns the same result. Without the repeatable keyword, the query returns a sample of a slightly different size each time you run it. If you modify your dataset and add more data, then repeatable doesn’t return the same result.

group-by Example

This query returns the counts of opportunities for each stage. Since the query operates on 10% of the dataset, the counts for each stage are approximately 1/10 of the original count.

1q = load "Opportunity" sample(10) repeatable(1);
2q = group q by 'StageName';
3q = foreach q generate 'StageName', count() as 'count';
4q = limit q 2000;

filter Example

This query returns only the won opportunities for each stage. Since the query operates on 10% of the dataset, the count for each stage is approximately 1/10 of the original count.

1q = load "Opportunity" sample(10);
2q = filter q by 'IsWon' == "true";
3q = group q by 'StageName';
4q = foreach q generate 'StageName', count() as 'count';
5q = limit q 2000;