Database Administrator

A data dictionary is used to store database information. It can be used to understand the internal information of an Oracle database, such as the table creator, creation time, tablespace, and user access permissions. DBAs must fully understand the

When creating a new user, you must specify the default tablespace; otherwise, the system tablespace will be treated as the default tablespace. This is not recommended. It is estimated that the default tablespace was not specified when a user was

The 64-bit CentOS6.3 system is installed with a minimal package. It is used as a local Web server and the entire process is recorded.Step 6: Install mysql5.5 database v5.5.28 Mysql starts from Version 5.5 and does not use./configure for compilation.

Definition: Row migration: Because of update, the rows become longer, the original blocks cannot be placed, the rows are moved into the new blocks, Line link: The line is too large at the beginning. For example, if you insert a row of bytes, you

Before Oracle 10 Gb, the warning log is located in the bdump folder, but 11 GB has changed the log and introduced ADR (a directory that stores the diagnostic logs and tracking files of the database ), it corresponds to the initialization parameter

The distinct keyword can only be used to filter all records in the query field that are the same (the record set is the same). If you want to specify a field, it does not work. In addition, the distinct keyword is sorted, Which is

Instance: Kernel. core_uses_pid = 1Kernel. shmall = 2097152Kernel. shmmax = 2147483648Kernel. shmmni = 4096Kernel. sem = 250 32000 100 128Fs. file-max = 65536Net. ipv4.ip _ local_port_range = 9000 65000Net. core. rmem_default = 4194304Net. core.

Oracle Data dictionary is a very important component of Oracle. Learning Oracle data dictionary is of great significance for database management. Below is the method I learned from my book to track the Oracle view. Here, let's make a mark! I.

1. replicate_do_db and replicate_ignore_db do not appear at the same time. It is prone to confusion. It is meaningless.Replicate_Do_DB: db1Replicate_Ignore_DB: db2 Statement mode:Use the use statementUse db1; insert into tb1 values (1 );Use db2;

Problem description; Install the Oracle11g client in SUSE10sp2 and create an aipcti user. If tnsping vsm (vsm is the service name under the client) fails, an error is returned:TNS-03505: Failed to resolve name, Used parameter

Use show parameter xx in sqlplus to view the Oracle-defined parameters, which are obtained by querying v $ parameter. In addition, some implicit parameters in Oracle cannot be directly queried through the show parameter method. Let's check the

Preface After installing MySQL, you must optimize and adjust various MySQL Parameter options. Although the MySQL system is highly scalable, it can run efficiently in an environment with sufficient hardware resources or in a few resource environments.

I. Linux platform It is very easy to uninstall Oracle on Linux, that is, to delete all files and folders under the Oracle installation directory. Ii. Windows Platform On Windows, how to thoroughly uninstall Oracle is described. Since it is quite

Linux: RHEL 6.3 Oracle: oracle 11g R2 (11.2.0.3) RHEL 6.3 is installed on two servers, oracle is installed on two servers, software is stored locally on the server, and database files are stored on the shared disk (iscsi used ), the first oracle

This record is a change operation record for the production scenario. It focuses on the Operation ideas and sequence, and strives to be rigorous and careful. The premise is that the customer is eager to deploy the application for stress testing when

I. Introduction In the previous steps of getting hibernate, every time you create a database table, you must create a corresponding * under entity *. hbm. xml configuration file. When there are many database tables, it will seriously affect the

Oracle Optimizer (CBO optimization) Before executing an SQL statement, Oracle needs to analyze the statement execution plan and then execute it according to the execution plan. The execution plan of the Analysis Statement is completed by the

Oracle uses the spfile . ora file as the startup parameter file. If the file does not exist, search for the spfile. ora file. If the spfile . ora and spfile. ora files do not exist The init . ora file is used. If none of the preceding three files

Ora_rowscn For each row of data, ora_rowscn returns the approximate time that each row was last modified. this is useful for determining when a row of data is modified. because Oracle uses transaction commit to track the data blocks of rows for scn,

Q: How to back up data under a field in a table in the Oracle database? This problem has plagued me and found a lot of information about it through Baidu search. But none of them can help me solve this problem. Solution: try to create a temporary