### 8.13.1 Measuring the Speed of Expressions and Functions

 To measure the speed of a specific MySQL expression or function, invoke the [`BENCHMARK()`](information-functions.html#function_benchmark) function using the [**mysql**](mysql.html) client program. Its syntax is [`BENCHMARK(*`loop_count`*,*`expr`*)`](information-functions.html#function_benchmark). The return value is always zero, but [**mysql**](mysql.html) prints a line displaying approximately how long the statement took to execute. For example:

```
mysql> SELECT BENCHMARK(1000000,1+1);
+------------------------+
| BENCHMARK(1000000,1+1) |
+------------------------+
|                      0 |
+------------------------+
1 row in set (0.32 sec)
```

 This result was obtained on a Pentium II 400MHz system. It shows that MySQL can execute 1,000,000 simple addition expressions in 0.32 seconds on that system.

 The built-in MySQL functions are typically highly optimized, but there may be some exceptions. [`BENCHMARK()`](information-functions.html#function_benchmark) is an excellent tool for finding out if some function is a problem for your queries.

