first rev - Quarry

SQL

WITH
  least_rev_dt AS (
    SELECT rev_timestamp AS dt, 'least_rev' AS approach
    FROM revision
    WHERE
      rev_id=(SELECT MIN(rev_id) FROM revision)),
  
  least_ar_rev_dt AS (
    SELECT ar_timestamp AS dt, 
    'leart_ar_rev' AS approach
    FROM archive
    WHERE ar_rev_id=(SELECT MIN(ar_rev_id) FROM archive)),
    
  min_rev_timestamp AS (
    SELECT MIN(rev_timestamp) AS dt, 
    'min_rev_dt' AS approach 
    FROM revision),
 
 min_ar_rev_timestamp AS (
   SELECT MIN(ar_timestamp) AS dt, 
   'min_ar_rev_dt' AS approach 
   FROM archive),
   
 all_dts AS ( SELECT * FROM least_rev_dt UNION ALL 
             SELECT * FROM least_ar_rev_dt UNION ALL 
             SELECT * FROM min_rev_timestamp UNION ALL 
             SELECT * FROM min_ar_rev_timestamp),
            
    
ranking AS ( SELECT *, ROW_NUMBER() OVER (ORDER BY dt) AS row_num FROM all_dts WHERE NOT DATE(dt) < DATE('2001-01-15'))

SELECT DATE(dt) AS dt, approach FROM ranking WHERE row_num = 1
SQL

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