If you specify Values analysis, Data Explorer performs Values analysis (described in Values) on every specified column in every specified input table, using this procedure:
- Combine as many counts for the columns in as few SELECT statements as possible.
- Put results in a temporary table. (Each SELECT statement is an INSERT SELECT statement.)
- Use INSERT SELECT statements to reorganize data for possibly multiple columns and move it to the output table.
- Count distinct values separately and update the output table.
If the count of distinct values fails (as it does when a column is too wide), Data Explorer sets the count for that column to null without affecting other results.
The analysis parameter Compute unique values for each column selected must be selected in order for the uniques parameter value to be returned with a non-null value.