http://www.jb51.net/article/45185.htm

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網(wǎng)站運(yùn)行很慢的時(shí)候，我就特別起知道為什么這么慢，所以我查啊查,數(shù)據(jù)庫絕對是很重要的一部分，里面運(yùn)行的sql是絕對不能放過的。平時(shí)做項(xiàng)目的時(shí)候，我也會注意sql語句的書寫，寫出一些高效的sql來，所以我會經(jīng)常測試自己寫的sql語句。我把我知道的二個方法，總結(jié)一下發(fā)出來。

一，show profiles 之類的語句來查看

1，查一下profile是不是打開了，默認(rèn)是不打開的。

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mysql> show profiles; Empty set (0.02 sec) mysql> show variables like "%pro%"; +---------------------------+-------+ | Variable_name | Value | +---------------------------+-------+ | profiling | OFF | | profiling_history_size | 15 | | protocol_version | 10 | | slave_compressed_protocol | OFF | +---------------------------+-------+ 4 rows in set (0.00 sec)

我查看一下profiles里面沒有東西，所以公司的電腦里面profile是沒有打開的，我查看了一下mysql變量，果然是OFF的。

2，開啟profile，然后測試

開啟profile

mysql> set profiling=1; Query OK, 0 rows affected (0.00 sec)

測試如下：

mysql> show tables; +----------------+ | Tables_in_test | +----------------+ | aa | | bb | | comment | | string_test | | user | +----------------+ 5 rows in set (0.00 sec) mysql> select * from aa; +----+------+------------+------+ | id | name | nname | sex | +----+------+------------+------+ | 2 | tank | bbbb,4bbbb | NULL | | 3 | zhang| 3,c,u | NULL | +----+------+------------+------+ 2 rows in set (0.00 sec) mysql> update aa set name='d'; Query OK, 2 rows affected (0.00 sec) Rows matched: 2 Changed: 2 Warnings: 0 mysql> delete from bb; Query OK, 2 rows affected (0.00 sec) mysql> show profiles; +----------+------------+------------------------+ | Query_ID | Duration | Query | +----------+------------+------------------------+ | 1 | 0.00054775 | show tables | | 2 | 0.00022400 | select * from aa | | 3 | 0.00026275 | update aa set name='d' | | 4 | 0.00043000 | delete from bb | +----------+------------+------------------------+ 4 rows in set (0.00 sec) mysql> show profile; +----------------------+-----------+ | Status | Duration | +----------------------+-----------+ | (initialization) | 0.0000247 | | checking permissions | 0.0000077 | | Opening tables | 0.0000099 | | System lock | 0.000004 | | Table lock | 0.000005 | | init | 0.0003057 | | query end | 0.0000062 | | freeing items | 0.000057 | | closing tables | 0.000008 | | logging slow query | 0.0000015 | +----------------------+-----------+ 10 rows in set (0.00 sec) mysql> show profile for query 1; +----------------------+-----------+ | Status | Duration | +----------------------+-----------+ | (initialization) | 0.000028 | | checking permissions | 0.000007 | | Opening tables | 0.0000939 | | System lock | 0.0000017 | | Table lock | 0.0000055 | | init | 0.000009 | | optimizing | 0.0000027 | | statistics | 0.0000085 | | preparing | 0.0000065 | | executing | 0.000004 | | checking permissions | 0.000258 | | Sending data | 0.000049 | | end | 0.0000037 | | query end | 0.0000027 | | freeing items | 0.0000307 | | closing tables | 0.0000032 | | removing tmp table | 0.0000275 | | closing tables | 0.0000037 | | logging slow query | 0.000002 | +----------------------+-----------+ 19 rows in set (0.00 sec) mysql> show profile for query 3; +----------------------+-----------+ | Status | Duration | +----------------------+-----------+ | (initialization) | 0.0000475 | | checking permissions | 0.0000077 | | Opening tables | 0.000026 | | System lock | 0.0000042 | | Table lock | 0.0000045 | | init | 0.0000205 | | Updating | 0.0000787 | | end | 0.0000567 | | query end | 0.000004 | | freeing items | 0.0000067 | | closing tables | 0.000004 | | logging slow query | 0.000002 | +----------------------+-----------+ 12 rows in set (0.00 sec)

二，timestampdiff來查看測試時(shí)間

mysql> set @d=now(); Query OK, 0 rows affected (0.00 sec) mysql> select * from comment; +------+-----+------+------------+---------------------+ | c_id | mid | name | content | datetime | +------+-----+------+------------+---------------------+ | 1 | 1 | ?? | 2222222211 | 2010-05-12 00:00:00 | | 2 | 1 | ?? | ????(??) | 2010-05-13 00:00:00 | | 3 | 2 | tank | ?????? | 0000-00-00 00:00:00 | +------+-----+------+------------+---------------------+ 3 rows in set (0.00 sec) mysql> select timestampdiff(second,@d,now()); +--------------------------------+ | timestampdiff(second,@d,now()) | +--------------------------------+ | 0 | +--------------------------------+ 1 row in set (0.00 sec)

這種方法有一點(diǎn)要注意，就是三條sql語句要盡量連一起執(zhí)行，不然誤差太大，根本不準(zhǔn)

set @d=now(); select * from comment; select timestampdiff(second,@d,now());

如果是用命令行來執(zhí)行的話，有一點(diǎn)要注意，就是在select timestampdiff(second,@d,now());后面，一定要多copy一個空行，不然最后一個sql要你自己按回車執(zhí)行，這樣就不準(zhǔn)了。

其實(shí)我覺得吧，真正要我們關(guān)心的是那些查詢慢的sql,因?yàn)檎嬲绊懰俣鹊氖撬麄?#xff0c;關(guān)于慢查詢的東西，有空寫一下。

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http://jingyan.baidu.com/article/d169e1864d254d436711d852.html

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shell之獲取數(shù)據(jù)庫SQL執(zhí)行時(shí)間（精確到毫秒）

shell之獲取時(shí)間（精確到毫秒）

需求：通過shell獲取數(shù)據(jù)庫當(dāng)前時(shí)間，并計(jì)算從打開數(shù)據(jù)庫連接--查詢--關(guān)閉數(shù)據(jù)庫連接所耗費(fèi)的時(shí)間（精確到毫秒）

步驟：

1、獲取時(shí)間（獲取時(shí)間）

注意：

1：連接數(shù)據(jù)庫的最后關(guān)閉時(shí)必須頂格寫否則報(bào)錯

2：shell無法直接獲取精確到毫秒的時(shí)間，需要通過計(jì)算獲取

方法/步驟

獲取時(shí)間（獲取時(shí)間）

[oracle@rhel6 zxx_shell]$ cat 3-time.sh?

#!/bin/bash

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var= ? ? ? ? ? ?#聲明全局變量

function getTiming()

{

? exec_start=$1

? exec_end=$2

??

? exec_start_s=`echo $exec_start | cut -d '.' -f 1` ?#獲取開始時(shí)間的秒

? exec_start_ns=`echo $exec_start | cut -d '.' -f 2` #獲取開始時(shí)間的納秒

? exec_end_s=`echo $exec_end | cut -d '.' -f 1` ??#獲取結(jié)束時(shí)間的秒

? exec_end_ns=`echo $exec_end | cut -d '.' -f 2`?#獲取結(jié)束時(shí)間的納秒

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? exec_time_ms=$[$[$[ 10#$exec_end_s - 10#$exec_start_s ] * 1000] + $[$[10#$exec_end_ns / 1000000] - $[10#$exec_start_ns / 1000000] ] ]

? nowdate=`date +%Y%m%d-%T`

? echo "--------$nowdate-------->":$exec_time_ms?

}

date= ??#聲明全局變量

function importTargetData()

{

? ? exec_start=`date +%s.%N` ??#獲取時(shí)間格式：秒.納秒

? ? sql="select sysdate from dual;"

? ? date=`sqlplus -s zxx/zxx@orclone <<EOF ?#接收數(shù)據(jù)庫查詢返回值

? ? ? set heading off

? ? ? set termout off

? ? ? set feedback off?

? ? ? $sql

? ? ? quit;

EOF` ? ? ? ???#一定要頂格寫

? ? exec_end=`date +%s.%N`

? ? var=$(getTiming $exec_start $exec_end) ?

? ??

}

? importTargetData

? echo $var

? echo $date

[oracle@rhel6 zxx_shell]$ ./3-time.sh?

--------20150805-15:26:19-------->:75

05-AUG-15

來源:https://blog.csdn.net/wangyueting415/article/details/65033543

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