> For the complete documentation index, see [llms.txt](https://upsolver.gitbook.io/content/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://upsolver.gitbook.io/content/reference-1/functions-and-operators/functions/aggregate/approx_count_distinct_each.md). # APPROX\_COUNT\_DISTINCT\_EACH Approximates the number of distinct values for each given group. ## Syntax ```sql APPROX_COUNT_DISTINCT([MAX_VALUES,] GROUP, VALUE) ``` ## Arguments #### `MAX_VALUES` Type: `integer` Default: no limit (Optional) The maximum number of groups. Groups beyond this amount are discarded. In some cases, discarding groups via this option may cause some data to be discarded from groups that would otherwise have been kept. #### `GROUP` Type: any The field by which to group the results. #### `VALUE` Type: any The field to count distinct values relative to each group. ## Returns Type: `array` Returns an array of key-value pairs where each `GROUP` is matched to the approximate number of distinct values `VALUE` seen for that group. If all input values are null, zero is returned. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://upsolver.gitbook.io/content/reference-1/functions-and-operators/functions/aggregate/approx_count_distinct_each.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.