Database Administrator

[Data recovery fault description] An important MySQL database server, 146 gb x 2, RAID1, and about 130 gb data volumes, stores about 200 ~ 300 databases. At ordinary times, the management staff directly compress every data warehouse dumps into A. GZ

Notes for setting the target database to archive in Oracle 1. Connect to sysdba SQL> conn/as sysdba 2. Check whether the instance is archived. SQL> select dbid, name, log_mode from v $ database; 3. Set archiving Parameters SQL> alter system

To install the Oracle database on Linux x86, perform the following steps: 1. install Linux and Oracle components; 2. Verify system requirements, Create users and groups, Create a directory, Configure Linux kernel parameters, Set Shell restrictions

1. type conversion functions: decimal, double, Integer, smallint, real, Hex (arg ), Date, time, timestamp, char, varchar Common examples: -- Convert to string type Oracle: select to_char (15.5000) from dual; DB2: select char (15.5000) from sysibm.

1. Create a special table to save the statistics of each table:Exec dbms_stats.create_stat_table ('s38', 'fys '); 2. Import the statistical information of each table to the ks38.fys table;Exec dbms_stats.export_table_stats ('s38', 'tcl _

1. log on to the system as the root user first; 2. Shut down the MySQL service or process: service mysqld stop/killall mysqld; 3. privileged to start MySQL:/usr/local/mysql/bin/mysqld_safe -- skip-grant-tables & or mysqld_safe -- skip-grant-tables --

When PL/SQL is used for import, an error occurs: IMP-00032: the SQL statement exceeds the buffer length. IMP-00008: the exported file contains unrecognized statements. At first, I thought it was because the Large_Pool settings of the database

MySQL creates a user and sets the access control permission Syntax: Grant all privileges on *. * TO 'username' @ '%' identified by 'Password' with grant option; Note: 1. "*. *" sets the user's control over databases and tables. For example, if

Welcome to phpMyAdmin 2.7.0-pl1 PhpMyAdmin tries to connect to the MySQL server, but the server rejects the connection. Check the host, user name, and password in config. inc. php and confirm that the information is consistent with the information

Some small functions in OracleRequirement: A. A string in the database table may contain"+"Example: ORC+001 It may not include"+"B. If the string contains"+", Then"+"Character example: ORC+001ORCC. If the string does not contain"+", The string is

It can call windows sql2000 database in php of Debian Ubuntu System System Installation SoftwareApt-get install php5-sybase/Etc/init. d/apache2 restart PHP code writing$ Msconnect = mssql_connect ("server", "User Name", "password ");$ Msdb = mssql_

In the development environment and UAT environment, you often encounter the need to clear archived logs. There are many ways to solve this problem. You can use rm to clear archived logs directly, or use the find command to find matching records to

1. How to query whether a service is registered with a static listener or a dynamic listener You can run the lsnrctl status Command to check whether a service is registered statically or dynamically. When the instance status is UNKNOWN, it indicates

Objective: To back up a user database at every night in CentOS 6.4: Use the scheduled task mechanism in linux and run the crontab command to export the database using the exp tool; then, let crontab call exp regularly to implement automatic backup.

Weibo will discuss how MySQL can reduce MySQL hang time When deleting a large table engine = innodb (30G + ). When buffer_pool is large (30 GB +), because the table is deleted, the entire buffer pool will be traversed to clean up data, resulting in

• Describes various conversion functions provided by SQL • TO_CHAR, TO_NUMBER, and TO_DATE conversion functions • Apply conditional expressions to SELECT statements Implicit and explicit data type conversion TO_CHAR, TO_DATE, and TO_NUMBER

The semicolon is the end character of the SQL statement. This is also true in hql, but hive does not recognize the semicolon intelligently as follows: Select concat (';', 'A') from lhc limit 1; FAILED: Parse Error: line cannot recognize input near

Theoretical Basis of the experiment: The increment of the sequence of SCN does not change with any database operation, even the RESETLOGS.RESETLOGS clears redo records not applied in all online log files. RESETLOGS only resets the log file's serial

Backup tools are limited to xtrabackup (2.0 +) Umask is no stranger. It sets the default permissions for files (directories). Generally, the permissions for newly created directories are 755 and those for files are 644; However, MySQL has 700

Requirements: 1. A customer table named Pers, whose primary key is the customer ID persnbr; 2. The seven columns in the pers table have foreign key constraints; 2. In the pers table, 0.1 million pieces of data are generated in batches (persnbr> = 100