Postgresql request to find duplicates

Duplicates.sql

SELECT * FROM (
	SELECT id[, other_fields…] ROW_NUMBER() OVER(PARTITION BY <field to search duplicates>) AS row 
	FROM <table>
) duplicates
WHERE duplicates.row > 1;

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SELECT <field to search duplicates>, COUNT(*) FROM <table> GROUP BY <field to search duplicates> HAVING COUNT(*) > 1;