为什么MySQL存储过程、函数和触发器对性能不好

As we can see, func3 (with four dead code calls that will never be executed, otherwise identical to func1) runs almost 3x slower compared to func1(); func3_nope() is identical in terms of response time to func3().

Visualizing All System Calls From Functions

To figure out what is happening inside the function calls, I used performance_schema/sys schema to create a trace with ps_trace_thread() procedure.

1.Get the thread_id for the MySQL connection:

mysql> select THREAD_ID from performance_schema.threads where processlist_id = connection_id();  
+-----------+  
| THREAD_ID |  
+-----------+  
|        49 |  
+-----------+  
1 row in set (0.00 sec)  

2.Run ps_trace_thread in another connection passing the thread_id=49:

mysql> CALL sys.ps_trace_thread(49, concat('/var/lib/mysql-files/stack-func1-run1.dot'), 10, 0, TRUE, TRUE, TRUE);  
+--------------------+  
| summary            |  
+--------------------+  
| Disabled 0 threads |  
+--------------------+  
1 row in set (0.00 sec)  
+---------------------------------------------+  
| Info                                        |  
+---------------------------------------------+  
| Data collection starting for THREAD_ID = 49 |  
+---------------------------------------------+  
1 row in set (0.00 sec)  

3.At that point I switched to the original connection (thread_id=49) and run:

mysql> select func1();  
+---------+  
| func1() |  
+---------+  
|       0 |  
+---------+  
1 row in set (0.00 sec)  

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