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: GraphQL (2015), SQLite, select, select count, Distributed SQL, TablePlus, Cache hit ratio, pg_stat_user_tables, EXPLAIN, Index (PostgreSQL)
• Databases: SQL, 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
• PostgreSQL: pg_dump, pgAdmin, DBeaver, Navicat, DataGrip, OmniDB, Adminer, psql, pg_ctl, docker-compose.xml PostgreSQL, PostgreSQL version, PostgreSQL logs, postgresql.conf, pg_hba.conf, Create database (PostgreSQL), Create user, createdb, GRANT, pg_stat, PostgreSQL VACUUM, EXPLAIN, pg stat activity, Autovacuum, ALTER DATABASE, PostgreSQL statistics collector, Shared buffers, EXPLAIN (PostgreSQL), EXPLAIN ANALYZE, Bitmap scan, EXPLAIN VERBOSE, EXPLAIN VERBOSE (PostgresSQL), WAL, ALTER USER, CREATE ROLE, \du, show users, \l, Index (PostgreSQL), The Statistics Collector, pganalyze, cron.schedule, Master