Database Administrator

Linux backs up MySQL Data every day Preface: If your MySQL database file is large, it may occupy a lot of server resources during backup. Therefore, the webmaster should try to select the minimum period of time for the visitor to execute the

Use cgroups to limit the resource occupation of MySQL Enterprise Backup Today, I encountered a problem: MySQL Enterprise Backup caused a heavy load on the I/O subsystem, slow application response, and system unavailability. So I want to restrict the

Use the new Oracle RAC 11gR2 feature renamedg to change the diskgroup name Environment Description:AIX7.1 + dual-node Oracle Rac 11.2.0.3 Because this Rac is not installed by your own department, it is installed by the Development Department and is

Install MySQL 5.1.7 in RedHat Linux 5 Install MySQL 5.1.7 in RedHat Linux 5 [Root @ bkjia ~] # Cd/home/app/mysql[Root @ bkjia mysql] # ls -- ExtractMySQL-community-5.1.73-1.rhel5.i386.rpm-bundle.tar[Root @ bkjia mysql] # tar-xvf MySQL-community-5.1.7

Oracle simple column-to-row Oracle simple column-to-row The requirement is to count the total salaries of different jobs in each department. SQL> select deptno, ename, job, sal from emp;DEPTNO ENAME JOB SAL---------------------------------------20

Usage modes of Oracle Indexes For some large SQL statements, most tuning scenarios have the feeling of being cool-fed. If the data is screened by millions or tens of millions, full table scan is an extremely resource-consuming process. However, if

Oracle not exists equivalence statement Not exists can be changed to left join + is null. It can be seen that the execution plan is the same before and after rewriting, and the resource consumption is the same, which means it is equivalent. SQL>

Oracle enhanced grouping Functions The ROLLUP () function is an extension of group by grouping statistics, which can achieve the sum of GROUP statistics. Now let's start preparing our testing environment. -- Create a new table employee_salary to

Create and apply PL/SQL packages Create and apply PL/SQL packages ① IntroductionA package is a combination of PL/SQL programming elements, such as related processes, functions, variables, constants, and cursors. It has the characteristics of an

How to configure an ACL report ORA-24247 Preface: ORA-24247 errors when sending messages to external via Oracle 11, detailed error messages are as follows: ERROR at line 1: ORA-24247: network access denied by access control list (ACL) ORA-06512: at "

Modify the Oracle Job sched Log Level and delete the running log Oracle jobs that have been running for a long time will generate a large number of running logs, which can be cleared through the following methods: 1. Create a job: Create job links

Detailed description of MySQL table structure modification MySQL alter table syntax======================================Add column [add column name]======================================① Alter table name add column name column type column

Notes for Oracle control file multiplexingBecause the control file is very important to the database, the control file is usually reused after the dbca database is created. For example, in Oracle10g, three control files are generated by default and

ORA-30009: connect by memory insufficient Today in the Oracle 11G environment manufacturing data encountered ORA-30009: connect by Operation memory is insufficient, 10g began to support XML, changed to xmltable can be. SQL> drop table t_range purge;

Mysqlbackup online configuration of MySQL Master/Slave Architecture Preface: MySQL databases are often used to build e-commerce platforms. e-commerce platforms mean that the platforms that make money for the company must be online 24 hours a day. We

Principles and experiments of Oracle automatic statistics collection Starting from Oracle Database 10 Gb, Oracle creates a scheduled task named GATHER_STATS_JOB by default after the Database is created, which is used to automatically collect CBO

Oracle analysis function ntile Oracle analysis function ntile With such A requirement, the scores of the course are divided into four levels to provide A, B, C, and D Performance for students. Drop table course purge;Create table course(Id

PL/SQL triggers PL/SQL triggers Triggers are a technology provided by many relational database systems. In the Oracle system, triggers and similar procedures and functions have PL/SQL blocks that declare, execute, and handle exceptions. ① Trigger

About semi-join in Oracle Table join is particularly important in SQL statements. External connections, internal connections, semi-connections, anti-connections, and other connections, there are still a lot of details in a simple connection. It is

Step-by-step introduction to databasesDatabase Table A database usually contains one or more tables. Each table is identified by a name (for example, "customer" or "order "). A table contains records (rows) with data ). The following example shows a