MySQL从5.0.37起，提供了profile的功能，对性能调试机器有用，不过今天在一台服务器上使用时却出了问题：
# /usr/local/mysql/bin/mysqld -V
/usr/local/mysql/bin/mysqld Ver 5.0.83-log for pc-linux-gnu on i686 (MySQL Community Server (GPL))
版本号是5.0.83，大于5.0.37，感觉应该可以使用profile功能，可是：
mysql> set profiling = 1;
ERROR 1193 (HY000): Unknown system variable ‘profiling’
出人意料，竟然无法使用profile功能。接着试试别的命令：
mysql> show profiles;
ERROR 1289 (HY000): The ‘SHOW PROFILES’ feature is disabled; you need MySQL built with ‘enable-profiling’ to have it working
这次的错误信息相对而言更明确了，说编译时没有激活enable-profiling选项。确认一下目前的编译参数：
# cat /usr/local/mysql/bin/mysqlbug | grep CONFIGURE_LINE
CONFIGURE_LINE=”./configure ‘–prefix=/usr/local/mysql’ ‘–localstatedir=/usr/local/mysql/data’ ‘–libexecdir=/usr/local/mysql/bin’ ‘–with-comment=MySQL Community Server (GPL)’ ‘–with-server-suffix=’ ‘–enable-thread-safe-client’ ‘–enable-local-infile’ ‘–enable-assembler’ ‘–with-pic’ ‘–with-fast-mutexes’ ‘–with-client-ldflags=-static’ ‘–with-mysqld-ldflags=-static’ ‘–with-zlib-dir=bundled’ ‘–with-big-tables’ ‘–with-yassl’ ‘–with-readline’ ‘–with-innodb’ ‘–with-ndbcluster’ ‘–with-archive-storage-engine’ ‘–with-blackhole-storage-engine’ ‘–with-csv-storage-engine’ ‘–without-example-storage-engine’ ‘–with-federated-storage-engine’ ‘–with-extra-charsets=all’ ‘CC=ccache /usr/local/gcc-4.3.2/bin/gcc -static-libgcc’ ‘CFLAGS=-g -O3 -march=i686′ ‘CXX=ccache /usr/local/gcc-4.3.2/bin/gcc -static-libgcc’ ‘CXXFLAGS=-g -O3 -march=i686′”
确实没enable-profiling选项，不过别以为简单加上这个选项之后重新编译一次就行了，实际上如果想编译成功，还得同时确保存在enable-community-features选项，可参阅官方文档。如果觉得记这些编译命令太烦，那就使用新版的MySQL吧，从5.1.28版本开始，这些选项缺省就是激活的。
补充点知识，查看nginx，apache，mysql，php的编译参数（假设都安装在/usr/local目录）：
查看nginx编译参数：/usr/local/nginx/sbin/nginx -V
查看apache编译参数：cat /usr/local/apache/build/config.nice
查看mysql编译参数：cat /usr/local/mysql/bin/mysqlbug | grep CONFIGURE_LINE
查看php编译参数：/usr/local/php/bin/php -i | grep configure