MySQL I/O Load by File

Ranks the most read and written files in bytes. Shows which table or file causes disk bottlenecks.

#io#performance_schema#disk

mysql · sql

SELECT file, count_read, total_read, count_write, total_written, total
FROM sys.io_global_by_file_by_bytes
LIMIT 20;

Operational Notes & Remediation Guidance

Verify in a staging environment prior to running in production. This is a read-only diagnostic query; it does not acquire exclusive locks.

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.

Other MYSQL Diagnostic Scripts

Lists active queries running longer than 60 seconds from the processlist. Fast diagnosis for slowdowns and lock pile-ups.

Uses the sys schema to show waiting and blocking sessions with lock modes. Resolves who is holding up whom in a single query.

Ranks tables by data, index and free space size. Core input for capacity planning and archiving decisions.

Uses sys.schema_unused_indexes to list indexes that were never used. Helps safely drop indexes that slow down writes.