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1, Understanding MHA 1. When is MHA MHA (MasterHigh Availability) is a set of excellent software for failover and master-slave replication in MySQL high availability environment. The emergence of MHA is to solve the problem of MySQL single point. During MySQL failover, MHA can automatically complete the failover operation within 0-30 seco ...

Basic concepts DB:DataBase (database, which actually exists as a file on the hard disk) DBMS: DataBase Management System MySQL Oracle SQL: structured query language, is a standard general language. When the SQL statement is executed, it will actually be compiled internally before executing the SQL. DBMS is responsible for executing SQL stateme ...

Classification of SQL classificationexplainData definition languageFor short, DDL(Data De "nition Language) is used to define database objects: database, table, column, etc.Data manipulation languageReferred to as DML (data management language), it is used to update the records of tables in the database.Data query languageDQL(Data Query L ...

Introduction case create table test01 ( a1 int(4) not NULL, a2 int(4) not NULL, a3 int(4) not NULL, a4 int(4) not NULL ); alter table test01 add index idx_a1_a2_a3_a4(a1,a2,a3,a4); ① explain select a1,a2,a3,a4 from test01 where a1=1 and a2=2 and a3=3 and a4=4; -- Recommended writing explain select a1,a2,a3,a4 from test01 where a4= ...

Table is the main form of data storage in database. It is composed of rows and columns, which is similar to common spreadsheet.The biggest difference between tables in MySQL and other databases is that they can use different storage engines. Storage Engine is a component used to manage, access and modify physical data in MySQL. Different storag ...

Relatively speaking, the writing is fairly complete. Basically, that's all you can use in your work. A good brain is better than a bad pen. Stored procedures, stored functions, engines, transactions, scheduled tasks, triggers, variables and so on are included. You can collect those you are interested in! 1. Connect to mysql mysql is divide ...

catalogue preface 1, MHA       1. Overview       2. Composition of MHA       3. Characteristics of MHA 2, Build MySQL MHA       1. Experimental ideas       2. Experimental environment       3. Experimental steps 3, Fault simulation   &nbs ...

catalogue 1. Meter lock   2. Row lock   two point one   Read uncommitted 2.1.1 analog dirty reading 2.2 read submitted 2.2.1 test dirty reading problem   2.2.2 non repeatable reading   2.2.3 repeatable   2.2.4 mvcc (to be supplemented) 2.2.5 unreal reading   2.2.6 serialization (to be supplemented) ...

Database programming (JDBC) 1. Database programming: JDBC JDBC, namely Java Database Connectivity. Is a Java API for executing SQL statements. It is a database connection specification in Java. This API is composed of some classes and interfaces in java.sql. Javax.sql. Package. It provides a standard API for Java developers to operate ...

Basic introduction and configuration Video link #Crazy God said sql Query data storage place Start service + enter database management system 1 – start local mysql service computer management system command line net stop/start mysqllin 2 – enter the management system with the password Username root password 12345 ...