docs: note hidden dimensions and sorting in pivot tables (#674)

Co-authored-by: mintlify[bot] <109931778+mintlify[bot]@users.noreply.github.com>

Author: mintlify[bot]

references/chart-types/table.mdx

@@ -81,6 +81,16 @@ To add a pivot in your table, move a dimension to the `column` section of your t
 
 You can move up to 3 dimensions as columns.
 
+### Hidden dimensions and sorting
+
+You can hide a dimension column from a pivot table while still using it to control sort order. Toggle the column's visibility off in the chart configuration panel — the dimension stops rendering as a row-index or pivot-column-header cell, and it's excluded from CSV and XLSX exports, but it continues to drive the SQL sort order and row grouping behind the scenes.
+
+This is useful when you want to sort rows by a value you don't want to display. For example, you can sort partners by `partner_id` while only showing `partner_name` in the table.
+
+<Note>
+  Rows are still grouped using the full set of dimensions, including hidden ones. Rows with the same visible values but different hidden-dimension values are kept as separate rows rather than collapsed together.
+</Note>
+
 ### Column limits
 
 Pivot tables have a default limit of 200 columns to ensure good performance. Large pivot tables with many columns can significantly slow down query execution and rendering times, so this limit helps keep your dashboards responsive.