Extracts the set of unique values from a column into an array stored in a new column. This function is typically part of an aggregation.
NOTE: Output order of nested values from an aggregation function cannot be determined in advance. The work to generate output values is done in parallel, which results in different ordering of any nested values for each execution run for each running environment.
Tip: To generate unique values for the generated array, apply the ARRAYUNIQUE function in the next step after this one. See ARRAYUNIQUE Function.