Cache hit ratio

PostgreSQL:

SELECT 
  sum(heap_blks_read) as heap_read,
  sum(heap_blks_hit)  as heap_hit,
  sum(heap_blks_hit) / (sum(heap_blks_hit) + sum(heap_blks_read)) as ratio
FROM 
  pg_statio_user_tables;

heap_read  |   heap_hit   |         ratio
-------------+--------------+------------------------
 37201451186 | 256244644067 | 0.87322560501639635699
(1 row)

heap_read | heap_hit | ratio
-----------+----------+-------
           |          |
(1 row)

Related terms

• TablePlus
• pg_stat_user_tables
• Autovacuum

See also

• SQL, NewSQL, RDMS: GraphQL (2015), SQLite, select, insert, select count, Distributed SQL, TablePlus, Cache hit ratio, pg_stat_user_tables, EXPLAIN, Index (PostgreSQL), DDL, SQL/MED, Group by, List users, SQL Injection, SQLAlchemy, CREATE USER, CREATE ROLE, EXPLAIN, ALTER DATABASE, REVOKE, NOLOCK, NOWAIT, EXISTS, Unique constraint, .sql
• Databases: Database management, SQL, NoSQL, Wide column, PostgreSQL, MariaDB, MySQL, Derby DB, MongoDB, Cassandra, SQLite, HSQL2, H2, RocksDB, Microsoft SQL Server, DB2, Oracle Database, Memcached, Berkeley DB, Collation, SingleStore, Amazon Aurora, Graph database, Amazon DynamoDB, PrestoDB, Cache hit ratio, ACID, WAL, ARIES, DBMS, OLTP, OLAP, Database Schema, CockroachDB, Tables, Views, Apache Druid, RDMS