APPROX_COUNT_DISTINCT_AGG takes as its input a column of details containing information about approximate distinct value counts, and enables you to perform aggregations of those counts.

For detail, specify a column of details created by the APPROX_COUNT_DISTINCT_DETAIL function or the APPROX_COUNT_DISTINCT_AGG function. This column is of data type BLOB.

You can specify this function in a SELECT statement with a GROUP BY clause to aggregate the information contained in the details within each group of rows and return a single detail for each group.

This function returns a BLOB value, called a detail, which contains information about the count aggregations in a special format. You can store details returned by this function in a table or materialized view, and then again use the APPROX_COUNT_DISTINCT_AGG function to further aggregate those details, or use the TO_APPROX_COUNT_DISTINCT function to convert the detail values to human-readable NUMBER values.


Refer to APPROX_COUNT_DISTINCT_AGG: Examples for examples of using the APPROX_COUNT_DISTINCT_AGG function in conjunction with the APPROX_COUNT_DISTINCT_DETAIL and TO_APPROX_COUNT_DISTINCT functions.