Online DDL：

一.FIC之前的添加刪除二級索引：

• 1.首先創建臨時表，定義目標新表的選項和索引
• 2.逐行拷貝數據到臨時表
• 3.插入行時更新索引信息
• 4.數據全部被拷貝到新表後，刪除舊表，rename新表

為保證數據一致性，舊表復制數據到新表的全程只允許讀，不允許改

二.5.1 5.5FIC新特性 fast index creation

• 1.創建二級索引給表加上共享S鎖
• 2.創建過程不需要重建表
• 3.刪除二級索引只需要更新內部視圖，並標記索引的空間可用，去除數據庫元數據的關於該索引的定義

依然只能讀，不允許改，但加快了修改索引的速度
因為聚簇索引的特性，主鍵索引修改依然需要通過舊方式copy table過程

三.5.6之後

• 1.之前FIC只對二級索引創建刪除有效，5.6之後將此特性擴展到添加列、刪除列，修改列類型、列重命名、設置默認值

Online DDL選項

索引的copy與inplace創建

一.ALGORITHM=COPY

• 1.新建帶索引(主鍵索引)的臨時表
• 2.將原表鎖定，禁止DML操作，只允許select查詢
• 3.將原表數據拷貝到臨時表
• 4.禁止讀寫，進行rename，升級字典鎖
• 5.完成創建索引操作

需要記錄undo和redo，效率不如inplace，短期占用buffer pool，影響性能

二.ALGORITHM=INPLACE

• 1.創建索引(二級索引，主鍵+普通字段)數據字典
• 2.加表共享鎖S，禁止DML，允許select查詢
• 3.讀取聚簇索引，構造新的索引項，排序並插入新索引
• 5.等待打開當前表的所有只讀事務提交
• 6.創建索引結束

避免重建表帶來的IO和CPU消耗，保證DDL期間的性能和並發

三.ALGORITHM=DEFAULT

• 1.alter table後面什麽都不加的時候，默認是這個方式
• 2.如果old_alter_table為OFF，默認就是inplace方式
• 3.inplace不支持則進行copy

四.lock選項

控制是否鎖表，根據不同的DDL操作類型表現不同，mysql原則是盡量不鎖表，但是修改主鍵這樣的昂貴操作不得不鎖表

• 1.LOCK=NONE
  ，允許DDL期間並發讀寫涉及的表，顯式指定時，當不支持對該表的繼續寫入，則alter語句失敗，是ALGORITHM=COPY的默認lock級別
• 2.LOCK=SHARED，DDL期間表上的寫操作會被阻塞，但是不影響select
• 3.LOCK=DEFAULT，讓mysql自己判斷lock模式，原則是盡量不鎖表
• 4.LOCK=EXCLUSIVE，DDL期間該表不可用，堵塞任何讀寫請求，使用場景：
  • 最短時間內完成
  • 短時間表不可用能剛接受

註意：

• 1.任何模式下，online DDL開始之前都需要一個短時間的排它鎖X來準備環境
• 2.當alter命令發出後，會首先等待該表上的其他操作完成
• 3.alter命令之後的其他請求會出現等待MDL鎖
• 4.alter完成之前，其他DDL也會被阻塞一小段時間？

https://www.cnblogs.com/zengkefu/p/5674945.html

ddl實現細節

Prepare階段

• 1.創建frm文件
• 2.持有exclusive-mdl鎖，禁止讀寫，速度非常快
• 3.根據alter類型，確定執行方式，檢查存儲引擎是否支持inplace，不支持則使用copy---copy,online-rebuild：重新組織表,online-norebuild：改數據字典即可
• 4.更新數據字典的內存對象
• 5.分配row_log對象記錄增量，記錄DDL期間數據修改的日誌，如果日誌量超過參數 innodb_online_alter_log_max_size 的上限，則DDL失敗
• 6.生成臨時ibd文件（rebuild類型)

ddl執行階段

• 1.降級exclusvie-mdl鎖，允許讀寫
• 2.掃描原表的聚簇索引每條記錄
• 3.遍歷新表的聚簇索引和二級索引，逐一處理
• 4.根據記錄構造對應的索引項
• 5.將構造索引項插入sort_buffer塊進行排序
• 6.將sort_buffer塊中的排序結果插入新的索引
• 7.處理ddl執行過程中產生的增量-row-log，rebuild類型需要

commit階段

• 1.升級到exclusive-mdl索引，禁止讀寫
• 2.應用最後row_log中產生的日誌
• 3.更新innodb的數據字典
• 4.提交事務-刷數據的redo日誌
• 5.修改統計信息
• 6.rename臨時ibd文件，frm文件
• 7.變更完成

http://blog.itpub.net/22664653/viewspace-2056953

DDL SQL組合使用

1.全部變更寫到一條sql裏面

alter table t1 add index idx1(c1),add unique index idx2(c2),change c4_old_name c4_new_name integer unsigned;

copy方式下，效率最高，只需要拷貝1次

2.每個變更一條sql

alter table t1 add index idx1(c1);
alter table t1 add unique index idx2(c2);
alter table t1 change c4_old_name c4_new_name integer unsigned not null;

測試

1.顯式開啟一個查詢事務，默認DDL並不好？理論與實際不一樣

• session1

mysql session 1 >use db1;
Database changed
mysql session 1 >begin;
Query OK, 0 rows affected (0.00 sec)

mysql session 1 >select * from t1;
+------+------+
| id   | name |
+------+------+
|    1 | yzw  |
+------+------+
1 row in set (0.00 sec)

mysql session 1 >

開始一個事務，執行簡單查詢

• session2

mysql session 2 >use db1
Database changed
mysql session 2 >alter table t1 add index idx_id(id);
Query OK, 0 rows affected (9 min 47.09 sec)
Records: 0  Duplicates: 0  Warnings: 0

被阻塞9分47.09秒

• session3

mysql session 3 >use db1;
Database changed
mysql session 3 >select * from t1;
+------+------+
| id   | name |
+------+------+
|    1 | yzw  |
+------+------+
1 row in set (9 min 37.60 sec)

被阻塞9分37.60秒

• session4

mysql session 4 >mysql session 4 >show processlist;
+----+------+--------------------+------+------------------+--------+---------------------------------------------------------------+-------------------------------------+
| Id | User | Host               | db   | Command          | Time   | State                                                         | Info                                |
+----+------+--------------------+------+------------------+--------+---------------------------------------------------------------+-------------------------------------+
| 47 | repl | 172.16.3.154:42173 | NULL | Binlog Dump GTID | 432908 | Master has sent all binlog to slave; waiting for more updates | NULL                                |
| 48 | repl | 172.16.3.153:57245 | NULL | Binlog Dump GTID | 432806 | Master has sent all binlog to slave; waiting for more updates | NULL                                |
| 53 | mha  | 172.16.3.152:43681 | NULL | Sleep            |      0 |                                                               | NULL                                |
| 67 | root | localhost          | db1  | Query            |     23 | Waiting for table metadata lock                               | alter table t1 add index idx_id(id) |
| 68 | root | localhost          | db1  | Query            |     14 | Waiting for table metadata lock                               | select * from t1                    |
| 69 | root | localhost          | NULL | Query            |      0 | starting                                                      | show processlist                    |
| 70 | root | localhost          | db1  | Sleep            |     36 |                                                               | NULL                                |
+----+------+--------------------+------+------------------+--------+---------------------------------------------------------------+-------------------------------------+
7 rows in set (0.00 sec)

session2的alter和session3的select被阻塞
都在等待MDL鎖 alter

2.第二個加了算法，時間更長，dml並發更好？理論與實際不一樣

• session1

mysql session 1 >begin;
Query OK, 0 rows affected (0.00 sec)

mysql session 1 >select * from t1;
+------+------+
| id   | name |
+------+------+
|    1 | yzw  |
+------+------+
1 row in set (0.00 sec)

開啟一個事務

• session2

mysql session 2 >use db1
Database changed
mysql session 2 >alter table t1 add index idx_id(id), algorithm=inplace,lock=none;
Query OK, 0 rows affected (9 min 34.48 sec)
Records: 0  Duplicates: 0  Warnings: 0

顯示指定inplace方式增加索引

• session3

mysql session 3 >use db1;
Database changed
mysql session 3 >select * from t1;
+------+------+
| id   | name |
+------+------+
|    1 | yzw  |
+------+------+
1 row in set (9 min 22.13 sec)

查詢被阻塞

• session4

mysql session 4 >show processlist;
+----+------+--------------------+------+------------------+--------+---------------------------------------------------------------+------------------------------------------------------------------+
| Id | User | Host               | db   | Command          | Time   | State                                                         | Info                                                             |
+----+------+--------------------+------+------------------+--------+---------------------------------------------------------------+------------------------------------------------------------------+
| 47 | repl | 172.16.3.154:42173 | NULL | Binlog Dump GTID | 500684 | Master has sent all binlog to slave; waiting for more updates | NULL                                                             |
| 48 | repl | 172.16.3.153:57245 | NULL | Binlog Dump GTID | 500582 | Master has sent all binlog to slave; waiting for more updates | NULL                                                             |
| 53 | mha  | 172.16.3.152:43681 | NULL | Sleep            |      1 |                                                               | NULL                                                             |
| 71 | root | localhost          | db1  | Sleep            |     45 |                                                               | NULL                                                             |
| 72 | root | localhost          | db1  | Query            |     20 | Waiting for table metadata lock                               | alter table t1 add index idx_id(id), algorithm=inplace,lock=none |
| 73 | root | localhost          | db1  | Query            |      7 | Waiting for table metadata lock                               | select * from t1                                                 |
| 74 | root | localhost          | NULL | Query            |      0 | starting                                                      | show processlist                                                 |
+----+------+--------------------+------+------------------+--------+---------------------------------------------------------------+------------------------------------------------------------------+
7 rows in set (0.00 sec)

等待MDL鎖

3.原有copy方式DDL

1.構造測試數據

sysbench --test=insert.lua --oltp-table-size=5000000 --mysql-table-engine=innodb --mysql-user=root --mysql-password=123456 --mysql-port=3306 --mysql-host=localhost --mysql-db=test --max-requests=0 --time=60 --oltp-tables-count=2 --report-interval=10 --threads=2 prepare

2.使用原有copy方式進行ddl

mysql session 1 >select version();
+------------+
| version()  |
+------------+
| 5.7.16-log |
+------------+
1 row in set (0.00 sec)

mysql session 1 >show create table sbtest1
    -> ;
+---------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table   | Create Table                                                                                                                                                                                                                                                                                                           |
+---------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| sbtest1 | CREATE TABLE `sbtest1` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `k` int(10) unsigned NOT NULL DEFAULT ‘0‘,
  `c` char(120) NOT NULL DEFAULT ‘‘,
  `pad` char(60) NOT NULL DEFAULT ‘‘,
  PRIMARY KEY (`id`),
  KEY `k_1` (`k`)
) ENGINE=InnoDB AUTO_INCREMENT=5000001 DEFAULT CHARSET=utf8 MAX_ROWS=1000000 |
+---------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql session 1 >show variables like ‘%old_alter_table%‘;
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| old_alter_table | OFF   |
+-----------------+-------+
1 row in set (0.01 sec)

mysql session 1 >set global old_alter_table=on;
Query OK, 0 rows affected (0.00 sec)

mysql session 1 >show variables like ‘old_alter_table‘;
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| old_alter_table | OFF   |
+-----------------+-------+
1 row in set (0.00 sec)

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

mysql session 1 >show variables like ‘old_alter_table‘;
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| old_alter_table | ON    |
+-----------------+-------+
1 row in set (0.00 sec)

mysql session 1 >show index from sbtest1;
+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table   | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| sbtest1 |          0 | PRIMARY  |            1 | id          | A         |     4804854 |     NULL | NULL   |      | BTREE      |         |               |
| sbtest1 |          1 | k_1      |            1 | k           | A         |      883154 |     NULL | NULL   |      | BTREE      |         |               |
+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
2 rows in set (0.00 sec)

2.刪除增加索引

會觸發copy操作，並在數據目錄產生臨時frm和ibd文件
其他DML會被阻塞，請求MDL鎖

• session1

mysql session 1 >alter table sbtest1 drop index k_1;
Query OK, 5000000 rows affected (55.42 sec)
Records: 5000000  Duplicates: 0  Warnings: 0

mysql session 1 >alter table sbtest1 add index k_1(k);
Query OK, 5000000 rows affected (1 min 20.26 sec)
Records: 5000000  Duplicates: 0  Warnings: 0

• session2

mysql session 2 >update sbtest1 set k=2496416 where id=1;
Query OK, 1 row affected (14.39 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql session 2 >update sbtest1 set k=2496417 where id=1; 
Query OK, 1 row affected (1 min 12.48 sec)
Rows matched: 1  Changed: 1  Warnings: 0

• session3

+-----+------+--------------------+------+------------------+--------+---------------------------------------------------------------+-----------------------------------------+
| Id  | User | Host               | db   | Command          | Time   | State                                                         | Info                                    |
+-----+------+--------------------+------+------------------+--------+---------------------------------------------------------------+-----------------------------------------+
|  47 | repl | 172.16.3.154:42173 | NULL | Binlog Dump GTID | 507514 | Master has sent all binlog to slave; waiting for more updates | NULL                                    |
|  48 | repl | 172.16.3.153:57245 | NULL | Binlog Dump GTID | 507412 | Master has sent all binlog to slave; waiting for more updates | NULL                                    |
|  53 | mha  | 172.16.3.152:43681 | NULL | Sleep            |      0 |                                                               | NULL                                    |
| 716 | root | localhost          | test | Query            |     46 | copy to tmp table                                             | alter table sbtest1 drop index k_1      |
| 834 | root | localhost          | test | Query            |      5 | Waiting for table metadata lock                               | update sbtest1 set k=2496416 where id=1 |
| 835 | root | localhost          | NULL | Sleep            |     35 |                                                               | NULL                                    |
| 836 | root | localhost          | db1  | Query            |      0 | starting                                                      | show processlist                        |
+-----+------+--------------------+------+------------------+--------+---------------------------------------------------------------+-----------------------------------------+


mysql session 3 >mysql session 3 >show processlist;
+-----+------+--------------------+------+------------------+--------+---------------------------------------------------------------+-----------------------------------------+
| Id  | User | Host               | db   | Command          | Time   | State                                                         | Info                                    |
+-----+------+--------------------+------+------------------+--------+---------------------------------------------------------------+-----------------------------------------+
|  47 | repl | 172.16.3.154:42173 | NULL | Binlog Dump GTID | 507617 | Master has sent all binlog to slave; waiting for more updates | NULL                                    |
|  48 | repl | 172.16.3.153:57245 | NULL | Binlog Dump GTID | 507515 | Master has sent all binlog to slave; waiting for more updates | NULL                                    |
|  53 | mha  | 172.16.3.152:43681 | NULL | Sleep            |      1 |                                                               | NULL                                    |
| 716 | root | localhost          | test | Query            |     27 | copy to tmp table                                             | alter table sbtest1 add index k_1(k)    |
| 834 | root | localhost          | test | Query            |     20 | Waiting for table metadata lock                               | update sbtest1 set k=2496417 where id=1 |
| 835 | root | localhost          | NULL | Sleep            |    138 |                                                               | NULL                                    |
| 836 | root | localhost          | db1  | Query            |      0 | starting                                                      | show processlist                        |
+-----+------+--------------------+------+------------------+--------+---------------------------------------------------------------+-----------------------------------------+
7 rows in set (0.00 sec)

• session4

[root@master test]# pwd
/mysqlData/data/test
[root@master test]# ls -ltr
total 2564148
-rw-r-----. 1 mysql mysql         61 Mar 13 10:45 db.opt
-rw-r-----. 1 mysql mysql       8632 Mar 13 11:25 sbtest2.frm
-rw-r-----. 1 mysql mysql 1224736768 Mar 13 11:26 sbtest2.ibd
-rw-r-----. 1 mysql mysql       8632 Mar 13 11:33 sbtest1.frm
-rw-r-----. 1 mysql mysql 1149239296 Mar 13 11:34 sbtest1.ibd
-rw-r-----. 1 mysql mysql       8632 Mar 13 11:35 #sql-663e_2cc.frm
-rw-r-----. 1 mysql mysql  251658240 Mar 13 11:35 #sql-663e_2cc.ibd

4.新特性online DDL

1.改成online DDL方式

並不影響DML

• session1

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

mysql session 1 >show variables like ‘%old_alter_table%‘;
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| old_alter_table | OFF   |
+-----------------+-------+
1 row in set (0.01 sec)

mysql session 1 >alter table sbtest1 drop index k_1;
Query OK, 0 rows affected (0.07 sec)
Records: 0  Duplicates: 0  Warnings: 0
# 索引瞬間被刪掉了

mysql session 1 >alter table sbtest1 add index k_1(k);
Query OK, 0 rows affected (9.45 sec)
Records: 0  Duplicates: 0  Warnings: 0

• session2

mysql session 2 >update sbtest1 set k=2496417 where id=1;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0
# 添加二級索引的時候，也不會阻塞DML

• session3

mysql session 3 >show processlist;
+------+------+--------------------+------+------------------+--------+---------------------------------------------------------------+--------------------------------------+
| Id   | User | Host               | db   | Command          | Time   | State                                                         | Info                                 |
+------+------+--------------------+------+------------------+--------+---------------------------------------------------------------+--------------------------------------+
|   47 | repl | 172.16.3.154:42173 | NULL | Binlog Dump GTID | 508423 | Master has sent all binlog to slave; waiting for more updates | NULL                                 |
|   48 | repl | 172.16.3.153:57245 | NULL | Binlog Dump GTID | 508321 | Master has sent all binlog to slave; waiting for more updates | NULL                                 |
|   53 | mha  | 172.16.3.152:43681 | NULL | Sleep            |      1 |                                                               | NULL                                 |
|  716 | root | localhost          | test | Query            |      1 | altering table                                                | alter table sbtest1 add index k_1(k) |
| 1328 | root | localhost          | test | Sleep            |      0 |                                                               | NULL                                 |
| 1329 | root | localhost          | db1  | Query            |      0 | starting                                                      | show processlist                     |
+------+------+--------------------+------+------------------+--------+---------------------------------------------------------------+--------------------------------------+
6 rows in set (0.00 sec)

5.大事務之前的online DDL

alter之前有大事務執行，ddl會被阻塞，且後面的所有其他所有請求都會被阻塞
操作DDL之前最好還是先檢查一下是否有大事務在進行中

• session1

mysql session 1 >select * from sbtest1 where c=‘long select before alter‘;
Empty set (2.49 sec)

• session2

mysql session 2 >alter table sbtest1 add index k_1(k);
Query OK, 0 rows affected (11.46 sec)
Records: 0  Duplicates: 0  Warnings: 0

• session3

mysql session 3 >select * from sbtest1 where c=‘long select after alter execution but not complete‘;
Empty set (3.69 sec)

• session4

mysql session 4 >show processlist;
+------+------+--------------------+------+------------------+--------+---------------------------------------------------------------+------------------------------------------------------------------------------------+
| Id   | User | Host               | db   | Command          | Time   | State                                                         | Info                                                                               |
+------+------+--------------------+------+------------------+--------+---------------------------------------------------------------+------------------------------------------------------------------------------------+
|   47 | repl | 172.16.3.154:42173 | NULL | Binlog Dump GTID | 508885 | Master has sent all binlog to slave; waiting for more updates | NULL                                                                               |
|   48 | repl | 172.16.3.153:57245 | NULL | Binlog Dump GTID | 508783 | Master has sent all binlog to slave; waiting for more updates | NULL                                                                               |
|   53 | mha  | 172.16.3.152:43681 | NULL | Sleep            |      1 |                                                               | NULL                                                                               |
| 1328 | root | localhost          | test | Query            |      1 | Waiting for table metadata lock                               | alter table sbtest1 add index k_1(k)                                               |
| 1329 | root | localhost          | test | Query            |      1 | Waiting for table metadata lock                               | select * from sbtest1 where c=‘long select after alter execution but not complete‘ |
| 1480 | root | localhost          | test | Query            |      2 | Sending data                                                  | select * from sbtest1 where c=‘long select before alter‘                           |
| 1619 | root | localhost          | NULL | Query            |      0 | starting                                                      | show processlist                                                                   |
+------+------+--------------------+------+------------------+--------+---------------------------------------------------------------+------------------------------------------------------------------------------------+
7 rows in set (0.00 sec)

6.添加刪除列，不加inplace算法

允許ddl期間進行並發DML操作，並產生臨時文件

• session1，添加刪除列

mysql session 1 >ALTER TABLE `sbtest2`     -> ADD COLUMN `f_new_col1` int(11) NULL DEFAULT 0,     -> ADD COLUMN `f_new_col2` varchar(32) NULL DEFAULT ‘‘ AFTER `f_new_col1`;
Query OK, 0 rows affected (51.50 sec)
Records: 0  Duplicates: 0  Warnings: 0


mysql session 1 >alter table sbtest2 drop column f_new_col1,    -> drop column f_new_col2;
Query OK, 0 rows affected (48.64 sec)
Records: 0  Duplicates: 0  Warnings: 0

• session2，進行update

mysql session 2 >update sbtest2 set c="update when add colomun ddl start" where c=‘33333‘;
Query OK, 0 rows affected (25.67 sec)
Rows matched: 0  Changed: 0  Warnings: 0

mysql session 2 >update sbtest2 set c="update when add colomun ddl start" where c=‘33333‘;
Query OK, 0 rows affected (6.15 sec)
Rows matched: 0  Changed: 0  Warnings: 0

• session3，查詢

mysql session 3 >select * from sbtest2 where c=‘select when add colomun ddl start‘;
Empty set (23.74 sec)

mysql session 3 >select * from sbtest2 where c=‘select when add colomun ddl start‘;
Empty set (2.24 sec)

• session4

mysql session 4 >show processlist;
+-------+------+--------------------+------+------------------+--------+---------------------------------------------------------------+------------------------------------------------------------------------------------------------------+
| Id    | User | Host               | db   | Command          | Time   | State                                                         | Info                                                                                                 |
+-------+------+--------------------+------+------------------+--------+---------------------------------------------------------------+------------------------------------------------------------------------------------------------------+
|    47 | repl | 172.16.3.154:42173 | NULL | Binlog Dump GTID | 523165 | Master has sent all binlog to slave; waiting for more updates | NULL                                                                                                 |
|    48 | repl | 172.16.3.153:57245 | NULL | Binlog Dump GTID | 523063 | Master has sent all binlog to slave; waiting for more updates | NULL                                                                                                 |
|    53 | mha  | 172.16.3.152:43681 | NULL | Sleep            |      0 |                                                               | NULL                                                                                                 |
| 11000 | root | localhost          | NULL | Query            |      0 | starting                                                      | show processlist                                                                                     |
| 11021 | root | localhost          | test | Query            |      9 | altering table                                                | ALTER TABLE `sbtest2` 
ADD COLUMN `f_new_col1` int(11) NULL DEFAULT 0, 
ADD COLUMN `f_new_col2` varc |
| 11110 | root | localhost          | test | Query            |      6 | updating                                                      | update sbtest2 set c="update when add colomun ddl start" where c=‘33333‘                             |
| 11113 | root | localhost          | test | Query            |      5 | Sending data                                                  | select * from sbtest2 where c=‘select when add colomun ddl start‘                                    |
+-------+------+--------------------+------+------------------+--------+---------------------------------------------------------------+------------------------------------------------------------------------------------------------------+
7 rows in set (0.00 sec)

mysql session 4 >show processlist;
+-------+------+--------------------+------+------------------+--------+---------------------------------------------------------------+--------------------------------------------------------------------------+
| Id    | User | Host               | db   | Command          | Time   | State                                                         | Info                                                                     |
+-------+------+--------------------+------+------------------+--------+---------------------------------------------------------------+--------------------------------------------------------------------------+
|    47 | repl | 172.16.3.154:42173 | NULL | Binlog Dump GTID | 523338 | Master has sent all binlog to slave; waiting for more updates | NULL                                                                     |
|    48 | repl | 172.16.3.153:57245 | NULL | Binlog Dump GTID | 523236 | Master has sent all binlog to slave; waiting for more updates | NULL                                                                     |
|    53 | mha  | 172.16.3.152:43681 | NULL | Sleep            |      1 |                                                               | NULL                                                                     |
| 11000 | root | localhost          | NULL | Query            |      0 | starting                                                      | show processlist                                                         |
| 11021 | root | localhost          | test | Query            |     22 | altering table                                                | alter table sbtest2 drop column f_new_col1,
drop column f_new_col2       |
| 11110 | root | localhost          | test | Query            |      6 | updating                                                      | update sbtest2 set c="update when add colomun ddl start" where c=‘33333‘ |
| 11113 | root | localhost          | test | Query            |      2 | Sending data                                                  | select * from sbtest2 where c=‘select when add colomun ddl start‘        |
+-------+------+--------------------+------+------------------+--------+---------------------------------------------------------------+--------------------------------------------------------------------------+
7 rows in set (0.00 sec)

• session5，產生臨時文件

[root@master test]# ls -ltr
total 4010036
-rw-r-----. 1 mysql mysql         61 Mar 13 10:45 db.opt
-rw-r-----. 1 mysql mysql       8632 Mar 13 11:56 sbtest1.frm
-rw-r-----. 1 mysql mysql 1275068416 Mar 13 11:57 sbtest1.ibd
-rw-r-----. 1 mysql mysql       8716 Mar 13 15:54 sbtest2.frm
-rw-r-----. 1 mysql mysql 1442840576 Mar 13 15:55 sbtest2.ibd
-rw-r-----. 1 mysql mysql       8632 Mar 13 15:57 #sql-663e_2b0d.frm
-rw-r-----. 1 mysql mysql 1388314624 Mar 13 15:58 #sql-ib87-1396920660.ibd

• 刪除的時候產生的臨時文件比ibd更大

[root@master test]# ls -ltrh
total 3.9G
-rw-r-----. 1 mysql mysql   61 Mar 13 10:45 db.opt
-rw-r-----. 1 mysql mysql 8.5K Mar 13 11:56 sbtest1.frm
-rw-r-----. 1 mysql mysql 1.2G Mar 13 11:57 sbtest1.ibd
-rw-r-----. 1 mysql mysql 8.5K Mar 13 16:10 sbtest2.frm
-rw-r-----. 1 mysql mysql 1.3G Mar 13 16:11 sbtest2.ibd
-rw-r-----. 1 mysql mysql 8.6K Mar 13 16:12 #sql-663e_2b0d.frm
-rw-r-----. 1 mysql mysql 1.4G Mar 13 16:13 #sql-ib90-1396920666.ibd

7.修改列，加inplace算法(5.7)

• 1).創建f_new_col2的時候長度是32

mysql session 1 >ALTER TABLE `sbtest2`     -> ADD COLUMN `f_new_col1` int(11) NULL DEFAULT 0,     -> ADD COLUMN `f_new_col2` varchar(32) NULL DEFAULT ‘‘ AFTER `f_new_col1`;
Query OK, 0 rows affected (1 min 4.21 sec)
Records: 0  Duplicates: 0  Warnings: 0

• 2).更改f_new_col2長度為50

mysql session 1 >ALTER TABLE sbtest2     -> CHANGE f_new_col2 f_new_col2 varchar(50) NULL DEFAULT ‘‘, algorithm=inplace ;
Query OK, 0 rows affected (0.09 sec)
Records: 0  Duplicates: 0  Warnings: 0

• 3).可以發現長度已經被更改

mysql session 1 >show create table sbtest2;
+---------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table   | Create Table                                                                                                                                                                                                                                                                                                                                                                                      |
+---------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| sbtest2 | CREATE TABLE `sbtest2` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `k` int(10) unsigned NOT NULL DEFAULT ‘0‘,
  `c` char(120) NOT NULL DEFAULT ‘‘,
  `pad` char(60) NOT NULL DEFAULT ‘‘,
  `f_new_col1` int(11) DEFAULT ‘0‘,
  `f_new_col2` varchar(50) DEFAULT ‘‘,
  PRIMARY KEY (`id`),
  KEY `k_2` (`k`)
) ENGINE=InnoDB AUTO_INCREMENT=5000001 DEFAULT CHARSET=utf8 MAX_ROWS=1000000 |
+---------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

• 4).再更改更長長度時不支持inplace，但是改成長度是50又支持，50改短或長都不支持？

mysql session 1 >ALTER TABLE sbtest2     -> CHANGE f_new_col2 f_new_col2 varchar(150) NULL DEFAULT ‘‘, algorithm=inplace ;
ERROR 1846 (0A000): ALGORITHM=INPLACE is not supported. Reason: Cannot change column type INPLACE. Try ALGORITHM=COPY.
mysql session 1 >ALTER TABLE sbtest2     -> CHANGE f_new_col2 f_new_col2 varchar(32) NULL DEFAULT ‘‘, algorithm=inplace ;
ERROR 1846 (0A000): ALGORITHM=INPLACE is not supported. Reason: Cannot change column type INPLACE. Try ALGORITHM=COPY.
mysql session 1 >ALTER TABLE sbtest2     -> CHANGE f_new_col2 f_new_col2 varchar(50) NULL DEFAULT ‘‘, algorithm=inplace ;
Query OK, 0 rows affected (0.01 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql session 1 >ALTER TABLE sbtest2     -> CHANGE f_new_col2 f_new_col2 varchar(32) NULL DEFAULT ‘‘, algorithm=inplace ;
ERROR 1846 (0A000): ALGORITHM=INPLACE is not supported. Reason: Cannot change column type INPLACE. Try ALGORITHM=COPY.
mysql session 1 >ALTER TABLE sbtest2     -> CHANGE f_new_col2 f_new_col2 varchar(88) NULL DEFAULT ‘‘, algorithm=inplace ;
ERROR 1846 (0A000): ALGORITHM=INPLACE is not supported. Reason: Cannot change column type INPLACE. Try ALGORITHM=COPY.

修改列類型應該要rebuild整張表

8.繼續上面的修改列長度(5.7)

ddl堵塞DML，但是不阻塞select

• 1).session1

mysql session 1 >ALTER TABLE sbtest2     -> CHANGE f_new_col2 f_new_col2 varchar(200) NULL DEFAULT ‘‘;
Query OK, 5000000 rows affected (1 min 28.96 sec)
Records: 5000000  Duplicates: 0  Warnings: 0

• 2).session2

mysql session 2 >update sbtest2 set c="update when add colomun ddl start" where c=‘33333‘;
Query OK, 0 rows affected (1 min 34.01 sec)
Rows matched: 0  Changed: 0  Warnings: 0

• 3).session3

mysql session 3 >select * from sbtest2 where c=‘select when add colomun ddl start‘;
Empty set (2.82 sec)

• 4).session4

mysql session 4 >show processlist;
+-------+------+--------------------+------+------------------+--------+---------------------------------------------------------------+--------------------------------------------------------------------------------+
| Id    | User | Host               | db   | Command          | Time   | State                                                         | Info                                                                           |
+-------+------+--------------------+------+------------------+--------+---------------------------------------------------------------+--------------------------------------------------------------------------------+
|    47 | repl | 172.16.3.154:42173 | NULL | Binlog Dump GTID | 524786 | Master has sent all binlog to slave; waiting for more updates | NULL                                                                           |
|    48 | repl | 172.16.3.153:57245 | NULL | Binlog Dump GTID | 524684 | Master has sent all binlog to slave; waiting for more updates | NULL                                                                           |
|    53 | mha  | 172.16.3.152:43681 | NULL | Sleep            |      1 |                                                               | NULL                                                                           |
| 11000 | root | localhost          | NULL | Query            |      0 | starting                                                      | show processlist                                                               |
| 11021 | root | localhost          | test | Query            |      3 | copy to tmp table                                             | ALTER TABLE sbtest2 
CHANGE f_new_col2 f_new_col2 varchar(200) NULL DEFAULT ‘‘ |
| 12186 | root | localhost          | test | Query            |      2 | Waiting for table metadata lock                               | update sbtest2 set c="update when add colomun ddl start" where c=‘33333‘       |
| 12189 | root | localhost          | test | Query            |      1 | Sending data                                                  | select * from sbtest2 where c=‘select when add colomun ddl start‘              |
+-------+------+--------------------+------+------------------+--------+---------------------------------------------------------------+--------------------------------------------------------------------------------+
7 rows in set (0.01 sec)

• 5).session5，copy肯定是產生臨時文件

[root@master test]# ls -ltrh
total 3.2G
-rw-r-----. 1 mysql mysql   61 Mar 13 10:45 db.opt
-rw-r-----. 1 mysql mysql 8.5K Mar 13 11:56 sbtest1.frm
-rw-r-----. 1 mysql mysql 1.2G Mar 13 11:57 sbtest1.ibd
-rw-r-----. 1 mysql mysql 1.4G Mar 13 16:13 sbtest2.ibd
-rw-r-----. 1 mysql mysql 8.6K Mar 13 16:15 sbtest2.frm
-rw-r-----. 1 mysql mysql 8.6K Mar 13 16:21 #sql-663e_2b0d.frm
-rw-r-----. 1 mysql mysql 648M Mar 13 16:22 #sql-663e_2b0d.ibd

https://www.cnblogs.com/zengkefu/p/5674945.html
https://dev.mysql.com/doc/refman/5.6/en/upgrading-from-previous-series.html

OAK DDL

5.6之前使用第三方工具進行ddl

1.oak_online_alter_table前提條件

• 1.單列唯一索引，聯合索引和聯合主鍵索引不可以，觸發mysqlbug
• 2.沒有外鍵foreign key
• 3.沒有定義觸發器，有的話也一棍打死

2.oak ddl流程

• 1.確認表符合oak_online_alter_table的執行條件
• 2.如果有觸發器，備份觸發器，刪除觸發器
• 3.預估oak命令執行時間，表有1億，1秒執行3000條，大概執行12個小時，計劃時間執行
• 4.進行新舊表數據校驗，如果DDL改變了表字段類型，可能導致表數據變化
• 5.表切換rename
• 6.刪除原表觸發器
• 7.刪除表

3.check list功能

./run_bat IP onlineddl_check port dbname tabname

4.檢查外鍵和觸發器SQL

• 1.information_schema.key_column_usage
• 2.select * from information_schema.key_column_usage where table_schema=dbname and table_name=tabname and referenced_table_name is not null
• 3.select * from information_schema.key_column_usage where referenced_table_schema=dbname and referenced_table_name=tabname;

5.安裝openark-kit工具包

wget -O /etc/yum.repos.d/oak.repo http://download.opensuse.org/repositories/home:LenzGr/CentOS_7/home:LenzGr.repo
install openark-kit

6.操作過程

• 1).構造測試數據

sysbench --test=insert.lua --oltp-table-size=500000 --mysql-table-engine=innodb --mysql-user=root --mysql-password=123456 --mysql-port=3306 --mysql-host=localhost --mysql-db=test --max-requests=0 --time=60 --oltp-tables-count=2 --report-interval=10 --threads=2 prepare

• 2).檢查是否有觸發器

select trigger_schema,trigger_name,event_object_schema,event_object_table from information_schema.triggers where event_object_schema=‘test‘;

• 3).執行online DDL

oak-online-alter-table -u root --ask-pass -S /usr/local/mysql/mysql.sock -d test -t sbtest1 -g new_sbtest1 -a "add last_update_time timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,add key last_update_time(last_update_time)" --sleep=300 --skip-delete-pass

執行ddl的時候，依然可以進行ddl操作

root@master 22:34:  [test]> insert into sbtest1 values(10000000,10000,‘AAAAA‘,‘BBBBB‘);
Query OK, 1 row affected (0.01 sec)

• 4).執行校驗

select sum(crc32(concat(ifnull(id,‘NULL‘),ifnull(k,‘NULL‘)))) as sum from sbtest1 union all \ 
select sum(crc32(concat(ifnull(id,‘NULL‘),ifnull(k,‘NULL‘)))) as sum from new_sbtest1;

# select count(*) from sbtest1 union all select count(*) from new_sbtest1;
root@master 22:34:  [test]> select count(*) from sbtest1 union all select count(*) from new_sbtest1;
+----------+
| count(*) |
+----------+
|   500001 |
|   291001 |
+----------+
2 rows in set (0.19 sec)
# 

desc sbtest1;
desc new_sbtest1;

• 5).因為在原表增加了觸發器，即使ddl完成之後，新的DML依然會插入到新表

root@master 22:34:  [test]> select trigger_schema,trigger_name,event_object_schema,event_object_table from information_schema.triggers where event_object_schema=‘test‘;
+----------------+----------------+---------------------+--------------------+
| trigger_schema | trigger_name   | event_object_schema | event_object_table |
+----------------+----------------+---------------------+--------------------+
| test           | sbtest1_AI_oak | test                | sbtest1            |
| test           | sbtest1_AU_oak | test                | sbtest1            |
| test           | sbtest1_AD_oak | test                | sbtest1            |
+----------------+----------------+---------------------+--------------------+
3 rows in set (0.00 sec)
root@master 22:38:  [test]> select count(*) from sbtest1 union all select count(*) from new_sbtest1;
+----------+
| count(*) |
+----------+
|   500001 |
|   500001 |
+----------+
2 rows in set (0.16 sec)

root@master 22:38:  [test]> insert into sbtest1 values(10000001,10000,‘AAAAA‘,‘BBBBB‘);
Query OK, 1 row affected (0.00 sec)

root@master 22:39:  [test]> select count(*) from sbtest1 union all select count(*) from new_sbtest1;
+----------+
| count(*) |
+----------+
|   500002 |
|   500002 |
+----------+
2 rows in set (0.16 sec)

• 6).表切換，更改數據字典

use test;
set names utf8;
rename table sbtest1 to old_sbtest1,new_sbtest1 to sbtest1;

• 7).刪除觸發器和原表

drop trigger sbtest1_AI_oak;
drop trigger sbtest1_AU_oak;
drop trigger sbtest1_AD_oak;
drop table old_sbtest1;

root@master 22:40:  [test]> show tables;
+----------------+
| Tables_in_test |
+----------------+
| old_sbtest1    |
| sbtest1        |
| sbtest2        |
+----------------+
3 rows in set (0.00 sec)

root@master 22:41:  [test]> select trigger_schema,trigger_name,event_object_schema,event_object_table from information_schema.triggers where event_object_schema=‘test‘;
+----------------+----------------+---------------------+--------------------+
| trigger_schema | trigger_name   | event_object_schema | event_object_table |
+----------------+----------------+---------------------+--------------------+
| test           | sbtest1_AI_oak | test                | old_sbtest1        |
| test           | sbtest1_AU_oak | test                | old_sbtest1        |
| test           | sbtest1_AD_oak | test                | old_sbtest1        |
+----------------+----------------+---------------------+--------------------+
3 rows in set (0.01 sec)

root@master 22:41:  [test]> drop trigger sbtest1_AI_oak;
Query OK, 0 rows affected (0.00 sec)

root@master 22:41:  [test]> drop trigger sbtest1_AU_oak;
Query OK, 0 rows affected (0.01 sec)

root@master 22:41:  [test]> drop trigger sbtest1_AD_oak;
Query OK, 0 rows affected (0.01 sec)

root@master 22:41:  [test]> drop table old_sbtest1;
Query OK, 0 rows affected (0.23 sec)

root@master 22:41:  [test]> show tables;
+----------------+
| Tables_in_test |
+----------------+
| sbtest1        |
| sbtest2        |
+----------------+
2 rows in set (0.00 sec)

7.用oak做Online DDL,如果rename那一步操作錯了？在從庫上rename了怎麽恢復？（包含舊表刪除和trigger刪除）.

• 1)第一種情況加索引的Online DDL
• 2)第二種情況加字段的Online DDL

發現rename錯表了？
再做一次drop ddl

不是從主庫進行ddl，選擇從庫ddl，從庫rename錯了，想恢復？

http://www.cnblogs.com/xuanzhi201111/p/4549250.html
http://www.cnblogs.com/xinysu/p/6732646.html#_lab2_4_3

mysql小白系列_13 Online DDL