Database Administrator

Exploration of MySQL MMM data inconsistency The slave points to the key log output of the new master. Through the log output, we can roughly understand the execution process of MMM automatic failover or online switching. -- Automatic failover and

Compile and install MySQL in Linux Recently I want to develop Hadoop, install MySQL, and test sqoop. Since MySQL is open source code, install it in source code. The following describes my test environment: VMware10 + Ubuntu14.04 Kylin Next, let's

MySQL MHA introduction and advantages MHA is the best choice for many enterprises that use MySQL databases for high availability. It is easy to use and powerful, and implements automatic master-slave failover Based on the MySQL replication

Basic Oracle database operation statements This article mainly introduces the basic statements and concepts of Oracle database management. 1. How to query the permissions of a role?A. System permissions contained in a roleSelect * from dba_sys_privs

MongoDB uses replica set backup to add new secondary replica members Problem description: In the production environment, when the read Pressure on secondary replica members is high, you can relieve the pressure by adding new secondary replica

Mysql-one of slow query logs, Mysql-one of slow logsSlow query log1. When no results are returned after a certain period of time, the slow query log is recorded.2. Slow query logs can help DBAs find SQL statements with slow execution efficiency and

Redis database of 03_NoSQL Database: list type, 03_nosqlredisZookeeper Lists type and Operation List is a linked List structure. The main function room is push, pop, get all values in a range, etc. In the operation, the key is interpreted as the

Mysql and Oracle Database concat () functions, oracleconcat I. Different Function Parameters Mysql supports concatenation of multiple strings: CONCAT (str1, str2 ,...) Oralce only supports concatenation of two strings. To splice multiple strings,

Hive exception: UDFArgumentTypeException No argument is expected, argumentexpected Background: Run hivesql in a market today. SQL is normal and there is no problem in data warehouse execution. However, after running in a market, the system always

Oracle express edition 11g cannot open 127.0.0.1: 8080, 11g127. 0.0.1 I installed oracle express edition 11g for oracle learning today, but after the installation is complete, I cannot open the Database Home Page: 127.0.0.1: 8080, baidu. How long

Use mysql workbench to generate the ergraph and workbencher Download and install mysql workbench Drawing In vain Download and install mysql workbench First, download mysql workbench. I use ubuntu 14.04LTS for my own

Oracle 10g Lsnrctl does not reflect the inability to connect to the database, oraclelsnrctlSymptom Description: The oracle version used is 10.2.0.1.0 in linux. If lsnrctl status is entered on the command line interface, no response is returned. If

In Linux, mysql forgets the root user password, and mysqlrootToday, when receiving a MYSQL server, I found that I forgot the password of the root user of MYSQL. I found that no root user password exists in various documents. Therefore, I need to

SQL server Functions, stored procedures, cursors, nested use of while and if statements, while nesting The main reason for writing this stored procedure is that you are too lazy to write data into the table every day. Not only learning, but also

PL/SQL if statement execution sequence, plsqlif statement The if statement Syntax of PL/SQL is defined as follows: IF condition THEN {... Statements ...} ELSIF condition THEN {... Statements ...} ELSE {... Statements ...} End if; Since PL/SQL is

Hadoop 2.2, hbase0.94.18 cluster installation, hadoophbase0.94.18 Here we install three clusters: Cluster ip Address: 192.168.157.132-134 Master: 192.168.157.132 Slaves: 192.168.157.small-134 Hbase depends on zookeeper for self-installation. 1.

Kettle connection Cluster Environment configuration, kettle Cluster Environment Original Works are from the blog of "Deep Blue blog". You are welcome to reprint them. Please note the following source when reprinting them. Otherwise, you will be held

[Introduction to database systems] ---- relational database (1), Introduction to Database Systems2.1 relational data structure and formal definition A relational database system supports relational models. A relational model consists of three

Redis persistence-AOF, Redis persistence-AOF Redis's persistent AOF mode records every write operation processed by the server in the form of logs. When the Redis service starts, it reads the file to re-build the database, to ensure that the data in

Oracle having, oraclehaving The HAVING clause is added to SQL because the WHERE keyword cannot be used with the aggregate function. Syntax:SELECT column_name, aggregate_function (column_name)FROM table_nameWHERE column_name operator valueGroup by