> The change explained above resulted in all users accessing accurate metadata about tables they have access to. Unfortunately, there were assumptions made in the past, that the list of columns returned by a query like this would only include the “default” database:

  SELECT
  name,
  type
  FROM system.columns
  WHERE
  table =        'http_requests_features'
  order by name;

    Note how the query does not filter for the database name. With us gradually rolling out the explicit grants to users of a given ClickHouse cluster, after the change at 11:05 the query above started returning “duplicates” of columns because those were for underlying tables stored in the r0 database.