mysqlreport显示Com_中change_db占用比例高的问题的解决方法

MySQL 5.1.28-rc-log   uptime 0 0:4:48    Thu Apr 30 14:04:58 2009

__ Key _________________________________________________________________
Buffer used   7.74M of 384.00M %Used:  2.02
 Current   52.89M      %Usage: 13.77
Write hit    0.00%
Read hit    91.97%

__ Questions ___________________________________________________________
Total     14.46k  50.2/s
 DMS      9.24k  32.1/s %Total: 63.90
 QC Hits    3.66k  12.7/s      25.33
 Com_     1.04k   3.6/s      7.19
 COM_QUIT    517   1.8/s      3.58
 -Unknown     1   0.0/s      0.01
Slow 1 s      4   0.0/s      0.03 %DMS:  0.04 Log: OFF
DMS       9.24k  32.1/s      63.90
 SELECT    9.21k  32.0/s      63.75     99.75
 UPDATE      23   0.1/s      0.16     0.25
 REPLACE      0    0/s      0.00     0.00
 DELETE      0    0/s      0.00     0.00
 INSERT      0    0/s      0.00     0.00
Com_      1.04k   50/s      44.4
 set_option   523   1.8/s      3.62
 change_db    510   50/s      44.4
 show_proces    5   0.0/s      0.03

__ SELECT and Sort _____________________________________________________
Scan        49   0.2/s %SELECT:  0.53
Range       16   0.1/s      0.17
Full join      2   0.0/s      0.02
Range check     0    0/s      0.00
Full rng join    0    0/s      0.00
Sort scan     55   0.2/s
Sort range    475   1.6/s
Sort mrg pass    0    0/s

__ Query Cache _________________________________________________________
Memory usage  12.02M of 150.00M %Used:  8.01
Block Fragmnt  0.01%
Hits      3.66k  12.7/s
Inserts     9.14k  31.8/s
Insrt:Prune  9.14k:1  31.8/s
Hit:Insert   0.40:1

__ Table Locks _________________________________________________________
Waited       0    0/s %Total:  0.00
Immediate   10.49k  36.4/s

__ Tables ______________________________________________________________
Open        58 of 512  %Cache: 11.33
Opened       64   0.2/s

__ Connections _________________________________________________________
Max used      4 of 2000   %Max:  0.20
Total       519   1.8/s

__ Created Temp ________________________________________________________
Disk table     1   0.0/s
Table       184   0.6/s  Size: 256.0M
File        5   0.0/s

__ Threads _____________________________________________________________
Running       2 of  2
Cached       2 of 150   %Hit: 99.23
Created       4   0.0/s
Slow        0    0/s

__ Aborted _____________________________________________________________
Clients       0    0/s
Connects      0    0/s

__ Bytes _______________________________________________________________
Sent      20.36M  70.7k/s
Received    1.37M  4.7k/s