percona-toolkit簡介
percona-toolkit是一組高級命令行工具的集合，用來執行各種通過手工執行非常複雜和麻煩的mysql和系統任務，這些任務包括：
檢查master和slave數據的一致性
有效地對記錄進行歸檔
查找重複的索引
對服務器信息進行彙總
分析來自日誌和tcpdump的查詢
當系統出問題的時候收集重要的系統信息
percona-toolkit工具包安裝
#wget https://www.percona.com/downloads/percona-toolkit/2.2.20/deb/percona-toolkit_2.2.20-1.tar.gz
#tar zxf percona-toolkit_2.2.20-1.tar.gz
#cd percona-toolkit-2.2.20/
#perl Makefile.PL 報錯如下：
[root@b0d81312ea9e percona-toolkit-2.2.20]# perl Makefile.PL
Can't locate ExtUtils/MakeMaker.pm in @INC (@INC contains: /usr/local/lib64/perl5 /usr/local/share/perl5 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5 .) at Makefile.PL line 1.
BEGIN failed--compilation aborted at Makefile.PL line 1.
該錯誤解決辦法：
#yum install perl-ExtUtils-CBuilder perl-ExtUtils-MakeMaker -y
問題解決，下面我繼續安裝
#perl Makefile.PL
#make && make install
安裝成功！
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下面我使用percona-toolkit中的pt-online-schema-change來給一個表增加字段
pt-online-schema-change用處：
ALTER tables without locking them.修改過程中不會造成讀寫阻塞，用於給大表添加字段。
實現原理：
如果表有外鍵，除非使用 –alter-foreign-keys-method 指定特定的值，否則工具不予執行。
1 創建一個和你要執行 alter 操作的表一樣的空表結構。
2 執行表結構修改，然後從原表中的數據到copy到 表結構修改後的表，
3 在原表上創建觸發器將 copy 數據的過程中，在原表的更新操作 更新到新表.
注意:如果表中已經定義了觸發器這個工具就不能工作了。
4 copy 完成以後，用rename table 新表代替原表，默認刪除原表。
# pt-online-schema-change --alter "ADD COLUMN num INT" D=sls,t=lisa
//給我mysql中的sls數據庫的lisa表增加一個num字段 D：指定數據庫 t:指定表
報錯如下：
Can't locate Time/HiRes.pm in @INC (@INC contains: /usr/local/lib64/perl5 /usr/local/share/perl5 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5 .) at /usr/local/bin/pt-online-schema-change line 3727.
BEGIN failed--compilation aborted at /usr/local/bin/pt-online-schema-change line 3727.
該錯誤的意思是：系統沒有安裝Perl的Time組件
該錯誤解決辦法：
# yum -y install perl-Time*
解決問題後再次添加字段：
# pt-online-schema-change --alter "ADD COLUMN num INT" D=sls,t=lisa
再次報錯如下：
Operation, tries, wait:
analyze_table, 10, 1
copy_rows, 10, 0.25
create_triggers, 10, 1
drop_triggers, 10, 1
swap_tables, 10, 1
update_foreign_keys, 10, 1
Exiting without altering `sls`.`lisa` because neither --dry-run nor --execute was specified. Please read the tool's documentation carefully before using this tool.
解決辦法：
# pt-online-schema-change --alter "ADD COLUMN num INT" D=sls,t=lisa --user=sls --socket=/tmp/mysql.sock --password=122541 --execute
報錯如下：
You do not have the PROCESS privilege at /usr/local/bin/pt-online-schema-change line 4330.
錯誤原因：沒有給sls用戶授權
解決辦法
mysql>grant all privileges on *.* to sls@localhost identified by "122541";
mysql> flush privileges;
解決問題後再次添加字段：
# pt-online-schema-change --alter "ADD COLUMN num INT" D=sls,t=lisa --user=sls --socket=/tmp/mysql.sock --password=122541 --execute
報錯如下：
No slaves found. See --recursion-method if host b0d81312ea9e has slaves.
Not checking slave lag because no slaves were found and --check-slave-lag was not specified.
Operation, tries, wait:
analyze_table, 10, 1
copy_rows, 10, 0.25
create_triggers, 10, 1
drop_triggers, 10, 1
swap_tables, 10, 1
update_foreign_keys, 10, 1
Altering `sls`.`lisa`...
Creating new table...
Created new table sls._lisa_new OK.
Altering new table...
Altered `sls`.`_lisa_new` OK.
2016-12-24T08:54:54 Dropping new table...
2016-12-24T08:54:54 Dropped new table OK.
`sls`.`lisa` was not altered.
The new table `sls`.`_lisa_new` does not have a PRIMARY KEY or a unique index which is required for the DELETE trigger.
錯誤原因：沒有給lisa表創建主鍵
解決辦法：
mysql> alter table lisa add id int not null primary key auto_increment;
//id列必須是lisa表中不存在的列。存在會報錯。
解決問題後再次添加字段：
# pt-online-schema-change --alter "ADD COLUMN num INT" D=sls,t=lisa --user=sls --socket=/tmp/mysql.sock --password=122541 --execute
成功了！！！
No slaves found. See --recursion-method if host b0d81312ea9e has slaves.
Not checking slave lag because no slaves were found and --check-slave-lag was not specified.
Operation, tries, wait:
analyze_table, 10, 1
copy_rows, 10, 0.25
create_triggers, 10, 1
drop_triggers, 10, 1
swap_tables, 10, 1
update_foreign_keys, 10, 1
Altering `sls`.`lisa`...
Creating new table...
Created new table sls._lisa_new OK.
Altering new table...
Altered `sls`.`_lisa_new` OK.
2016-12-24T09:09:15 Creating triggers...
2016-12-24T09:09:15 Created triggers OK.
2016-12-24T09:09:15 Copying approximately 12 rows...
2016-12-24T09:09:15 Copied rows OK.
2016-12-24T09:09:15 Analyzing new table...
2016-12-24T09:09:15 Swapping tables...
2016-12-24T09:09:15 Swapped original and new tables OK.
2016-12-24T09:09:15 Dropping old table...
2016-12-24T09:09:15 Dropped old table `sls`.`_lisa_old` OK.
2016-12-24T09:09:15 Dropping triggers...
2016-12-24T09:09:15 Dropped triggers OK.
Successfully altered `sls`.`lisa`.
成功了！！！
終於成功了！！我已經愛上我自己！！哈哈哈