Database Administrator

Decompress: Decompress the compressed package and move the bin folder in the extracted folder to/usr/local/mongodb. Create the directory mongodb/data/db and mongo/logs under home/tiantao /. Create a file mongodb. log in logs Use the root user to

Analytic functions compute an aggregate value based on a group of rows. they differ from aggregate functions in that they return multiple rows for each group. the group of rows is called a window and is defined by the analytic_clause. for each row,

1. Use telnet to log on to 10.149.187.18. The username is root and the password is root & admin. 2. Enter su-Oracle. 3. Enter Sqlplus and the user name system and password oracle. 4. Use the following statement to delete the original tablespace:Drop

1. Reduce the control file. If a control file is corrupted, we need to remove the corrupt control file. Steps:1. Modify the parameter file and verify2. Stop the database3. Start the database4. Verify and view v $ controlfile The following is the

A redo log group can contain one or more log members, which should be stored on different disks as disk log images. The same group of Members has the same content, if you do not have multiple disks, you do not have to create multiple log members for

Because the company needs to add computers to the domain, the computer name is modified. In addition, Oracle is rarely used at ordinary times, and services are started manually. In the afternoon, Oracle was suddenly used for a test. It was found

I encountered a problem during development and was troubled to find time. This is the case, Because our current system database uses Oracle, and I like The related statements are tested in pl/SQL developer before being written into the program. In

Convert data in table t_rows to Column DisplayCreate table 't_ rows '('Dt _ str' varchar (20) not null,'Name' varchar (20) not null,'Age' int (11) NOT NULL) ENGINE = InnoDB default charset = utf8; The result of the t_rows row isMysql> SELECT 'dt _

Install EBS All are modified using the root user. 1. Create the user's specified Oracle user directory/export/home/oracle 2. Create a user group dba; 3. Add oracle to the dba group; 4. Modify the host file backup hosts. bak Cd etc/inet Increase in

1. Environment preparation:Install three MYSQL servers.A 192.168.1.8B 192.168.1.88C 192.168.1.188 Ring Structure: 192.168.1.8 master 192.168.1.88 slave192.168.1.88 master 192.168.1.188 from192.168.1.188 master 192.168.1.8 slave 2. Change the

Today, the customer reported that the query was slow. Because the query was in a production environment, the test was not allowed. Therefore, refer to the following blog to export the statistics to the test server for SQL statement optimization. 1.

Use RMAN on Oracle 11gR2 for full-database migration Background: Database IP SID Port Database Version Target DB 192.168.1.20. Orcl 1521 11.2.0.1.0 Auxiliary DB 192.168.1.20.(It can be the same

A service has been installed.MysqlInstance.Mysqld_multiCommand to add an instance 1. Assume that there is an existingMysqlInstance, itsBasedirIs/Usr/local/mysql,The data directory is/Usr/local/mysql/data,The configuration file is/Etc/my. cnf # Mkdir/

In MySQL 5.1.x, the process of creating and deleting clustered indexes is as follows: 1. Create an empty table with the same structure as the original table, and then create a clustered index; 2. copy the data from the original table to the new

1. Enable archivelog SQL> shutdown immediate;SQL> startup mount;SQL> alter system set log_archive_dest_1 = 'location = d:/arc' scope = both;SQL> alter database archivelog;SQL> alter database open; 2. Backup Control File 2.1 generate the controlfile

Send a shotgun to a table: (1) insert into table_name [(column [, column...])] select_statementOnly one table can be inserted at a time, but the performance is higher than writing multiple insert statements. In addition, Oracle also provides create

The cache mechanism simply caches the SQL text and query results. If the same SQL statement is run, the server directly retrieves the results from the cache without parsing and executing the SQL statement. If the table is changed, all cache queries

Some people ask whether the locks of QueryCache (QC) in MySQL are "global locks" or "Table locks ". Here is a brief description. 1. Basic QC concepts This is a memory structure implemented in the MySQL layer (non-engine layer). The basic rule is to

When the database table size is large and the load is high, it is inevitable that the time consumed by an SQL statement is prolonged. Half a month ago, a scheduled task ran for eight hours in the early morning and suddenly fell helpless. Finally,

Recently, the program needs to generate DDL statements to modify the database table of the Oracle database. Therefore, I have summarized the situation of modifying the database table of the Oracle database as follows: 1. ADD a column: alter table