Database Administrator

(Linux parameters) Open the/etc/my. cnf file and modify the following settings. If not, add it manually. When adjusting the settings, please do your best, which depends on the configuration of your server, especially the memory size. The following

I. Mount the optical drive in Linux: Mount-t iso9660/dev/cdrom/mnt/cdrom Unmount the optical drive umount/dev/cdrom The drive eject is displayed. Push drive eject-t 2. Install MySQL

I have previously introduced the usage of SELECT... FOR UPDATE, but the locking data is a distinction. Because InnoDB defaults to Row-Level Lock, MySQL will only execute Row lock (only Lock the selected data example) If a specified Primary Key is

"Think" (Think ). When Mr. Thomas J. Watson joined IBM in 1914 and became an IBM company, he came up with such a simple motto. Later, this became the term of instruction for every IBM employee, no matter what role they took, as long as they needed

Method 1:Under/usr/local/mysql/bin:./Mysqladmin-u root password 'new _ password'This method is usually used for installation. Method 2:In mysql:Mysql> UPDATE user SET password = PASSWORD ('new _ password') WHERE user = 'root ';Mysql> flush

Problem 1: An error occurred while logging on to mysql.ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql. sock' (2)Solution:1) The default mysql. sock file is in the/tmp directory.2) Establish a soft connection,

Notes for MySQL Master/Slave 1. Try not to use stored procedures and triggers. Stored procedures can behave strangely with statement based replication 2. Try not to use temporary tables. For example, a memory table. Some programs prefer to

Oracle concatenates values of different columns into a string -- Concatenates values of different columns into a string using the concatenation operator "|" or CONCAT ('',''). -- Method 1: RecommendedSelect s. TEAM | '**' | S. NAME | '**' | S. JOB_

1) if you have not forgotten the password, you can use UPDATE to directly edit the user table to change the password: Enter mysql-u rootMysql> use mysql;Mysql> UPDATE user SET Password = PASSWORD ('newpass') WHERE user = 'root ';Mysql> flush

Extent indicates the range. In Oracle databases, extent management provides extent management local (local management) and extent management dictionary (data dictionary management) The default value is local. There are two ways to increase the size

Note:It is officially recommended to migrate to the same version, for example, 10.2.0.1 (32) to 10.2.0.1 (64 ).Upgrade to 10.2.0.5 (64 ). I. Environment IntroductionSource databaseOperating system version: OEL5.8 32bitDatabase Version: 10.2.0.1

1. What is Alibaba uard? DataGuard is a high-availability technology specifically designed for Oracle databases launched by oracle. It was called Standby Dtabase before 8i and officially changed its name from 9i to DataGuard. Generally, there are at

Oracle 11g parallel DML (PDML) Parallel DML applications have significant scalability and performance when accessing large objects in the demo-support system DSS environment. PDML cannot be used as a feature to speed up OLTP applications. PDML is

1. symptom: An error is reported when the database is opened in the last step after the recovery of the data files from different hosts is successful. For example: SQL> alter database open resetlogs; Error: ORA-01152: file 1 was not restored from a

Today, we will briefly introduce how to set up SGA. 1. sga_target ParameterAlter system set sga_target = 40000 m scope = both;Features:1). ASMM automatic shared memory managementA: ASMM (automatic shared memory management) is a new feature of Oracle.

1. Oracle multi-Table query Multi-Table query refers to queries based on two or more tables or views. Question: Display employee name, employee salary, and department name [Cartesian set ]? Select t. ename, t. sal, t1.dnamefrom emp t, dept t1where t.

Preface: We know there are three ways to call the Data Pump. Here, I will never use the command line but the first script method. The reasons for dropping the command line are as follows: ① Operating system restrictions on the number of CLI

One day early morning, I received a db Fault Warning and went to the machine for check. mysql was restarted by the myqld daemon. Check/var/log/messages and the recent dmesg and find that the mysql process is killed by oom. The following is an

Using PL/SQL profiler to analyze PL/SQL code is the most effective way to quickly locate PL/SQL code segments. In the previous article, using PL/SQL profiler to locate the PL/SQL bottleneck Code describes how to install PROFILER and provides

With autotrace, you can see the Predicate Information in some databases. Sometimes you cannot see it because the plan_table version is old. The solution is as follows: SQL> set autotrace traceonly SQL> select u. name2 from user u3 where u.