diff --git a/PostgreSQL/description/index_in_cache.sql b/PostgreSQL/description/index_in_cache.sql
new file mode 100644
index 0000000..62359bc
--- /dev/null
+++ b/PostgreSQL/description/index_in_cache.sql
@@ -0,0 +1,2 @@
+SELECT sum(idx_blks_read) as idx_read, sum(idx_blks_hit)  as idx_hit, (sum(idx_blks_hit) - sum(idx_blks_read)) / sum(idx_blks_hit) as ratio
+FROM pg_statio_user_indexes;