CREATE OR REPLACE VIEW stream_summary AS

WITH
  stream_count AS (
    SELECT
      stream_name,
      COUNT(id) AS message_count
    FROM
      messages
    GROUP BY
      stream_name
  ),

  total_count AS (
    SELECT
      COUNT(id)::decimal AS total_count
    FROM
      messages
  )

SELECT
  stream_name,
  message_count,
  ROUND((message_count / total_count)::decimal * 100, 2) AS percent
FROM
  stream_count,
  total_count
ORDER BY
  stream_name;