How to Identify Unused Index in PostgreSQL

See the below Query to find Unused index in PostgreSQL

SELECT s.schemaname,
       s.relname AS tablename,
       s.indexrelname AS indexname,
       pg_relation_size(s.indexrelid) AS index_size,
       s.idx_scan,s.idx_tup_read,s.idx_tup_fetch
FROM pg_catalog.pg_stat_user_indexes s
   JOIN pg_catalog.pg_index i ON s.indexrelid = i.indexrelid
WHERE s.idx_scan = 0     
  AND 0 <>ALL (i.indkey)  
  AND NOT i.indisunique   
  AND NOT EXISTS          
         (SELECT 1 FROM pg_catalog.pg_constraint c
          WHERE c.conindid = s.indexrelid) 
ORDER BY pg_relation_size(s.indexrelid) DESC;