Database Administrator

Install MySQL with yum in CentOS 7 First, CentOS7 does not support mysql, because you know the charge, so mariadb is integrated internally, and mysql installation will conflict with the mariadb file, so you need to uninstall mariadb first, follow

MyBatis Study Notes Speaking of mybatis, let's first talk about ibatis. mybatis3.X is a later version of ibatis2.X, which has many more powerful functions than ibatis. 1. Comparison between mybatis and ibatis 1.1 In terms of relationship ing,

Oracle listener service enabled Run the netca command to enable the Oracle listening service. Dialog Box Select listener service configuration, and click Next Select Add listener and click Next The name of the listener. Default Value.

MongoDB query documentSyntax The syntax format of MongoDB data query is as follows: >db.COLLECTION_NAME.find() The find () method displays all documents in an unstructured manner. If you want to read data in a readable manner, you can use the pretty

Use Redis to store the follow relationship Redis provides a wide range of data types. Compared with relational databases or simple Key-Value storage (such as Memcached), Redis data models are more similar to actual data models. For example, in the

Oralce creates a userPrerequisites Note that you must first Log On As SYSDBA. You can select the logon role on some development tools.If it is a command lineAs sysdbaCreate user process To create an Oracle database, you can use the SQL developer

MySQL OOM troubleshooting 1 The mysql database of a game business is hit by OOM on multiple servers, but what is the cause of OOM? In fact, the direct cause of OOM is not complicated. It is because the server memory is insufficient and the kernel

Description of Oracle process and memory dump Dump Process status:SQL> alter session set events 'immediate trace name processstate level 10 ';Or SQL> oradebug dump processstate 10 Dump system status:SQL> alter session set events 'immediate trace

Snapshot standby features in Oracle 11g Among Oracle 11g, data guard is the most attractive. In addition to the Real-Time query feature of active data guard (you can open the physical standby database in read-only mode while the MRP process can

Create a stored procedure instance in MySQL The MySQL stored procedure is a new feature added since MySQL 5.0. The advantages of stored procedures are as follows. However, the most important thing is the execution efficiency and SQL code

Install MySQL on Ubuntu source code for problem solving and Security Optimization 0. DescriptionOf course, MySQL is installed in a variety of ways. on Ubuntu, you can install it using apt-get. The advantage is that it is fast and convenient.

MySQL index push-Down Technology The whole idea of index push-down is as follows: To see how this optimization works, consider first how an index scan proceeds when Index Condition Pushdown is not used: Get the next row, first by reading the index

Oracle uses SQL to transmit tablespaces Source environment: RHEL 6.4 + Oracle 11.2.0.4Target environment: RHEL 6.4 + Oracle 11.2.0.4 dual-node DGRequirement: use SQL to transmit the tablespace DBS_D_JINGYU from the source environment to the target

Socket programming: byte order When it comes to socket programming, it will certainly be subject to byte sequence conversion. For a string, there is no difference in the byte order. Just like writing, the memory is like paper, and the string is

Oracle segment contraction1. Understand CIDR Block contraction Application Scenario: If you perform insert, update, and delete operations on a table frequently, a large number of fragments may occur after a long time. Oracle introduces the segment

PostgreSQL avg () function The AVG function of PostgreSQL is used to find the average value of a field in various records. To understand the AVG function, the table COMPANY has the following records:Testdb # select * from COMPANY;Id | name | age |

MySQL high availability solutions Mysql-mmm is the master replication manager of mysql, which provides the following functions:High Availability (similar to keepalived's vip Floating Technology)Only one database write operation is provided at the

MySQL performance query and Configuration Overview View MySQL database performance:Show proceelist view the database connection status and total number of connectionsShow globalstatus like 'max _ used_connections '; view the maximum response

Oracle statement execution tracking An interface on the system often times out to submit data (more than 3 seconds), while I only need 17 ms to execute insert in the background database (Oracle. The client that submits data does not have any

ORA-09817 troubleshooting ORA-09817 error solved one case sharing. When you log on to a development database, the following error occurs: When an error is reported, the system prompts that the audit file fails to be written because there is no