How to remove partial duplicates from a table
WITH duplicates as 
(
    SELECT id_page, id_site,
           row_number() over (partition by id_site order by id_site, create_date) rn
    FROM   pages
    WHERE  label = '2018-12-15'
)
DELETE FROM pages 
WHERE  id_page IN (SELECT id_page 
                   FROM   duplicates
                   WHERE  rn &gt; 1);