È possibile utilizzare la query seguente per trovare l'utilizzo dell'indice e la dimensione dell'indice:
Il riferimento è tratto da questo blog.
SELECT
pt.tablename AS TableName
,t.indexname AS IndexName
,to_char(pc.reltuples, '999,999,999,999') AS TotalRows
,pg_size_pretty(pg_relation_size(quote_ident(pt.tablename)::text)) AS TableSize
,pg_size_pretty(pg_relation_size(quote_ident(t.indexrelname)::text)) AS IndexSize
,to_char(t.idx_scan, '999,999,999,999') AS TotalNumberOfScan
,to_char(t.idx_tup_read, '999,999,999,999') AS TotalTupleRead
,to_char(t.idx_tup_fetch, '999,999,999,999') AS TotalTupleFetched
FROM pg_tables AS pt
LEFT OUTER JOIN pg_class AS pc
ON pt.tablename=pc.relname
LEFT OUTER JOIN
(
SELECT
pc.relname AS TableName
,pc2.relname AS IndexName
,psai.idx_scan
,psai.idx_tup_read
,psai.idx_tup_fetch
,psai.indexrelname
FROM pg_index AS pi
JOIN pg_class AS pc
ON pc.oid = pi.indrelid
JOIN pg_class AS pc2
ON pc2.oid = pi.indexrelid
JOIN pg_stat_all_indexes AS psai
ON pi.indexrelid = psai.indexrelid
)AS T
ON pt.tablename = T.TableName
WHERE pt.schemaname='public'
ORDER BY 1;
SELECT relname, seq_scan-idx_scan AS too_much_seq, case when seq_scan-idx_scan>0 THEN 'Missing Index?' ELSE 'OK' END, pg_relation_size(relid::regclass) AS rel_size, seq_scan, idx_scan FROM pg_stat_all_tables WHERE schemaname='public' AND pg_relation_size(relid::regclass)>80000 ORDER BY too_much_seq DESC;