Bug #55066 provide status variable to show current myisam_mmap_used
Submitted: 8 Jul 2010 4:39
Reporter: Shane Bester (Platinum Quality Contributor) Email Updates:
Status: Verified Impact on me:
None 
Category:MySQL Server: General Severity:S4 (Feature request)
Version:5.1, 5.5 OS:Any
Assigned to: CPU Architecture:Any
Tags: compressed tables, mmap, myisam_mmap_size

[8 Jul 2010 4:39] Shane Bester 
Description:
variable myisam_mmap_size can be specified as the maximum amount of memory to use for mmap'd myisam tables, however at runtime there is no way to see the current usage, which is stored in myisam_mmap_used variable.

there is also no description in the documentation of what happens when this limit specified by myisam_mmap_size is reached.

How to repeat:
http://dev.mysql.com/doc/refman/5.1/en/server-system-variables.html#sysvar_myisam_mmap_siz...

show global variables like 'myisam_mmap_used'; #empty
show global variables like 'myisam_mmap_size'; #value

Suggested fix:
maybe it can be done before or during the work on http://forge.mysql.com/worklog/task.php?id=5302
[8 Jul 2010 12:48] MySQL Verification Team 
oops, i meant: show global status like 'myisam_mmap_used'; #empty
[20 Mar 2013 9:13] MySQL Verification Team 
And make  myisam_mmap_size a dynamic variable, please.
[20 Mar 2013 9:14] MySQL Verification Team 
See bug #68724