MySQL InnoDB Buffer Pool Hit Ratio

Compares buffer pool read requests against disk reads to compute the hit ratio. Tells you whether memory sizing is sufficient.

#innodb#buffer-pool#cache-hit

mysql · sql

SELECT
  (SELECT variable_value FROM performance_schema.global_status WHERE variable_name='Innodb_buffer_pool_read_requests') AS read_requests,
  (SELECT variable_value FROM performance_schema.global_status WHERE variable_name='Innodb_buffer_pool_reads')         AS disk_reads,
  ROUND(100 * (1 -
    (SELECT variable_value FROM performance_schema.global_status WHERE variable_name='Innodb_buffer_pool_reads') /
    NULLIF((SELECT variable_value FROM performance_schema.global_status WHERE variable_name='Innodb_buffer_pool_read_requests'), 0)
  ), 3) AS hit_ratio_pct;

Operational Notes & Remediation Guidance

Target is 99%+ in OLTP environments. Lower ratios indicate memory pressure or poorly indexed queries evicting hot pages.

Production Safety & Execution Standards

This script is designed for read-only diagnostics; it does not alter schema or modify data directly.
Prior to executing on production systems under high load, verify the target database version (Min. Version: 5.7).
Exercise caution with mutating actions (e.g., terminating sessions or dropping indexes) referenced in the notes section.

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