How to use Mysql's Query-rewrite
This article introduces the knowledge of "how to use Mysql's Query-rewrite". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!
1 enable or disable
/ usr/local/mysql/bin/mysql-uroot-p`cat / etc/sqlpass `- P3306-h227.0.0.1
< $BASEDIR/share/install_rewriter.sql /usr/local/mysql/bin/mysql -uroot -p`cat /etc/sqlpass ` -P3306 -h227.0.0.1 < $BASEDIR/share/uninstall_rewriter.sql mysql>Show variables like 'rewrite_%'
+-+ +
| | Variable_name | Value |
+-+ +
| | rewriter_enabled | ON |
| | rewriter_verbose | 1 | |
+-+ +
Mysql > use query_rewrite
Mysql > show tables
+-+
| | Tables_in_query_rewrite |
+-+
| | rewrite_rules |
+-+
1 row in set (0.00 sec)
[mysqld]
Rewriter_enabled=ON
2 simple exercises
Mysql > insert into rewrite_rules (pattern,pattern_database,replacement) values ('select?', 'test','select? + 1')
Mysql > call flush_rewrite_rules ()
Mysql > select 1
+-+
| | 1: 1 | |
+-+
| | 2 |
+-+
3 removal of type conversion
Mysql > show create table tb\ G
* * 1. Row *
Table: tb
Create Table: CREATE TABLE `tb` (
`id`int (10) DEFAULT NULL
`name` varchar (20) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
Mysql > select * from tb
+-+ +
| | id | name |
+-+ +
| | 1 | 12345678 |
| | 1 | 12345671 |
| | 1 | 12345672 |
| | 1 | 12345673 |
| | 1 | 12345674 |
| | 1 | 12345675 |
| | 1 | 12345676 |
| | 1 | 12345677 |
| | 1 | 12345679 |
+-+ +
Mysql > explain select * from tb where name=12345677
+-- +
| | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+-- +
| | 1 | SIMPLE | tb | NULL | ALL | idx_name | NULL | NULL | NULL | 9 | 11.11 | Using where |
+-- +
Mysql > insert into rewrite_rules (pattern,pattern_database,replacement) values ("select * from tb where name=?", "test", "select * from tb where name= cast (? as char character set utf8)")
Query OK, 1 row affected (0.08 sec)
Think about it: why not just write? Replace with'?' Because? If it is wrapped in single quotation marks, it will be invalid!
Mysql > call flush_rewrite_rules ()
Query OK, 0 rows affected (0.09 sec)
Mysql > select * from tb where name=12345678
Mysql > show warnings
+- -- +
| | Level | Code | Message | |
+- -- +
| | Note | 1105 | Query 'select * from tb where name=12345678' rewritten to' select * from tb where name= cast (12345678 as char character set utf8)'by a query rewrite plugin |
+- -- +
1 row in set (0.00 sec)
4 compatible error reporting after changing field name
Mysql > select * from tb where uid=1
ERROR 1054 (42S22): Unknown column 'uid' in' where clause'
Mysql > insert into rewrite_rules (pattern,pattern_database,replacement) values ("select * from tb where uid=?", "test", "select * from tb where id=?")
Query OK, 1 row affected (0.06 sec)
Mysql > call flush_rewrite_rules ()
Query OK, 0 rows affected (0.06 sec)
That's all for "how to use Mysql's Query-rewrite". Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!
