Prevent Caching to FlashCache¶

FlashCache increases performance by caching data on SSDs. It works even better when only hot data is cached. This feature prevents the caching of the unwanted blocks of data.

Better utilization of FlashCache partitions is achieved when caching of rarely used data is avoided. Use of this feature prevents blocks of data from being cached to FlashCache during a query.

Usage of the feature is as follows:

SELECT /* sql_no_fcache */ ...

The mysqldump binary was changed to use this option.

Version-Specific Information¶

5.5.8-20.0: Full functionality available.

5.5.27-29.0: Variable have_flashcache introduced.

System Variables¶

variable have_flashcache¶

Version Info:	5.5.27-29.0 – Variable introduced
Command Line:	No
Config File:	No
Scope:	Global
Dynamic:	No
Variable Type:	Boolean
Range:	Yes/No

This variable shows if the server was compiled with Flashcache support.

Status Variables¶

variable Flashcache_enabled¶

Scope:	Global
Variable Type:	Boolean
Range:	OFF/ON

This status variable shows if the Flashcache support has been enabled.

Other Information¶

The feature is a port of the original Facebook change.