Bug #55171 How much sort_buffer_size are actually used?
Submitted: 12 Jul 2010 7:32
Reporter: Mikiya Okuno Email Updates:
Status: Verified Impact on me:
None 
Category:MySQL Server: Performance Schema Severity:S4 (Feature request)
Version: OS:Any
Assigned to: Marc Alff

[12 Jul 2010 7:32] Mikiya Okuno
Description:
"How much sort_buffer_size, read_buffer_size, read_rnd_buffer_size and join_buffer_size actually are used?" is often a significant question when tuning server parameters, and there's no way to retrieve such information form a running server at this moment.

If we have a way to get a statistics for such information, parameter tuning will be very simple and our lives will be much easier. I guess P_S is the best module to implement this feature, but other modules such as profiling are okay.

How to repeat:
n/a

Suggested fix:
n/a
[15 Jul 2010 19:39] Peter Gulutzan
Perhaps we'd want (global and/or local)
current + maximum i.e. high water mark +
number of times overflow or eviction happened,
for a lot of variables that have sizes
("show variables like '%size';" gives an indication).
It's the sort of thing we used to do with
SHOW STATUS, but indeed a performance_schema
table might be more appropriate.