以下範例試用在Centos 5.x，MySQL 5.0環境下

啟用query log功能
以drupal的資料庫連結多，開啟此功能，可預期query log檔案很快就變會很大，建議debug問題時才開啟。

1. $vi /etc/my.cnf

在[mysqld]區塊內設定加入

[mysqld]
log=/var/log/mysqld.general.log

2. mysql不會自動依設定產生mysqld.general.log，要手動加。

$ touch /var/log/mysqld.general.log
$ chown mysql.mysql /var/log/mysqld.general.log

3. 重新啟動mysqld，用瀏覧器連結網站，查看是否有產出log資料

$ /etc/init.d/mysqld restart
$ tail -f /var/log/mysqld.general.log

log資料

 2 Query       SELECT * FROM languages ORDER BY weight ASC, name ASC
 2 Query       SELECT data, created, headers, expire, serialized FROM cache WHERE cid = 'variables:zh-hant'
 2 Query       SELECT COUNT(pid) FROM url_alias
 2 Query       SELECT src FROM url_alias WHERE dst = 'node' AND language IN('zh-hant', '') ORDER BY language DESC, pid DESC

啟用slow query log功能

1. $ vi /etc/my.cnf

在[mysqld]區塊內設定加入
5.0版

[mysqld]
// 單位是秒，預設是10秒，最小值是1
log-slow-queries = 5
log-slow-queries = /var/log/mysql-slow.log
log-long-format

5.1.29版後

[mysqld]
slow_query_log
slow_query_log_file = /var/log/mysql-slow.log
long_query_time = 5
log-long-format

2. mysql不會自動依設定產生mysql-slow.log，要手動加。

$ touch /var/log/mysql-slow.log
$ chown mysql.mysql /var/log/mysql-slow.log

3. 重新啟動mysqld，用瀏覧器連結網站，查看是否有產出log資料

$ /etc/init.d/mysqld restart
$ tail -f /var/log/mysql-slow.log

log資料

# Time: 090317 18:46:59
# User@Host: root[root] @ localhost []
# Query_time: 12  Lock_time: 0  Rows_sent: 242515  Rows_examined: 242515
SELECT * FROM `portal`.`search_index`;

使用mysqldumpslow 指令分析mysql-slow.log，結果是耗費最多時間的slow query依順排出。

// query 7次，每次耗費106.43秒
Count: 7  Time=106.43s (745s)  Lock=0.00s (0s)  Rows=9366.9 (65568), aaa[aaa]@localhost
  SELECT * FROM `aaa`.`vtiger_crmentity`
// query 1次，每次耗費58.00秒
Count: 1  Time=58.00s (58s)  Lock=0.00s (0s)  Rows=51515.0 (51515), aaa[aaa]@localhost
  SELECT * FROM `aaa`.`product_mac2`
Count: 1  Time=42.00s (42s)  Lock=0.00s (0s)  Rows=1000.0 (1000), aaa[aaa]@[215.86.72.122]
  SELECT * FROM aaa.product_mac2 LIMIT N
Count: 6  Time=38.00s (228s)  Lock=0.00s (0s)  Rows=130972.3 (785834), aaa[aaa]@localhost
  SELECT * FROM `aaa`.`vtiger_audit_trial`

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