I am not sure that I understand how Power BI direct query works under the hood and whether Power BI optimise the query or not. Assume I have a filter (slicer with single selection) binding on column ColumnX in order to filter data on table: TableY
When user select value on slicer, does Power BI optimise query like:
SELECT * FROM TABLE tableY
WHERE ColumnX = 'Value'
Or, Power BI get all data from TableY and then filter happens in memory