Use and analysis of show profile optimized by MySQL

show profile yes mysql Analysis provided sql One of my tools , Its function is to record the latest execution 15 strip sql sentence , And record sql Detailed time-consuming execution 、CPU、 Memory consumption , It can help us quickly locate sql Statement and optimize ,show profile The default is off , And only live in the current session after opening , In other words, it needs to be turned on before each use .

On state

1、 Check to see if it's on （on： Turn on ,off： close ）

show variables like 'profiling'

2、 Turn on show profile

#  This on state is session Level , It means that if you don't use it for a while, it will turn off automatically 
set profiling=on;

To analyze

Do something casually first sql sentence , Skip here ...

1、 see profile list

show profiles;

If you execute show profiles appear Empty set, Otherwise, it is not opened show profile; Otherwise, it is not implemented sql sentence

2、 function sql The diagnosis

#  Here Query_ID Namely show profiles  Query to the Query_ID
show profile cpu,block io for query Query_ID

It mainly depends on Duration Execution time of

3、show profile Common query parameters of .

• ALL： Show all overhead information .
• BLOCK IO： Display block IO expenses .
• CONTEXT SWITCHES： Context switching overhead .
• CPU： Show CPU Overhead information .
• IPC： Show send and receive overhead information .
• MEMORY： Display memory overhead information .
• PAGE FAULTS： Display page error overhead information .
• SOURCE： Display and Source_function,Source_file,Source_line Related expense information .
• SWAPS： Shows the number of exchanges overhead information .

4、 Optimization of diagnosis results

• If ruguoconverting HEAP to MyISAM. Indicates that the query result is too large , Out of memory , Data moved to disk .
• If Creating tmp table. Indicates creating a temporary table . Copy the data to the temporary table first , Delete the temporary table after use .
• If Copying to tmp table on disk. Copy the temporary table in memory to disk , dangerous ！！！
• If locked. Indicates that the table is locked during execution .

If in show profile The diagnosis showed that 4 Any one of the results , shows sql Statements need to be optimized .