RESET QUERY CACHE - MySQL

Overview

The RESET QUERY CACHE command in MySQL allows users to clear the query cache, which stores the results of previously executed queries for faster retrieval. This command is primarily used to ensure that subsequent queries are executed against the most up-to-date data in the database, particularly after data modifications or schema changes.

Syntax

RESET QUERY CACHE

Options/Flags

This command does not have any available options or flags.

Examples

Simple usage:

RESET QUERY CACHE;

Checking if the query cache was successfully reset:

SHOW STATUS LIKE 'Qcache%';

Common Issues

  • Queries not using the updated data: If queries are still returning cached results after resetting the query cache, ensure that the query_cache_type system variable is set to 0 (OFF).
  • Performance overhead: Resetting the query cache can be resource-intensive for large caches. Consider using FLUSH QUERY CACHE instead, which only removes specific cached queries.

Integration

The RESET QUERY CACHE command can be used in conjunction with other MySQL commands to optimize performance and data integrity:

  • After data manipulation operations: INSERT, UPDATE, and DELETE operations should be followed by RESET QUERY CACHE to invalidate cached queries that may no longer be accurate.
  • After schema changes: CREATE TABLE, ALTER TABLE, and DROP TABLE operations require RESET QUERY CACHE to update cached queries that reference the affected tables.
  • FLUSH QUERY CACHE: Removes specific cached queries instead of the entire cache.
  • SHOW STATUS LIKE 'Qcache%': Displays information about the query cache, including its size and hit rate.
  • SET query_cache_type = 0: Disables the query cache entirely.