Database Administrator

Audit is used to monitor the database operations performed by users. Oracle stores Audit trail results in OS files or databases. 1. To use audit, you must activate audit. SQL> conn/as sysdba is connected. SQL> show parameter

Indexes are the main means to accelerate table content access, especially for queries involving connections to multiple tables. This is an important part of database optimization. We need to understand why indexes are needed, how indexes work, and

Because group by actually performs sorting operations, and compared with order by, group by mainly only performs grouping operations after sorting. Of course, if other Aggregate functions are used during grouping, Some Aggregate functions are

BKJIA quick translation: what is the use of random row extraction from database tables? Because sometimes you want to present random information to users. The following describes how to extract random row code from several popular databases. BKJIA

Take MySql as an example. Create two data tables in the MySQL database and insert some data respectively. The sample script is as follows: 　drop table table1;    CREATE TABLE `andrew`.`table1`    (    `name` VARCHAR(32) NOT NULL,   

For any database management system, memory allocation is definitely one of its core, so many people who want to know more about a database management system, I hope to have a look, and I am no exception. Memory usage MySQL database memory usage is

I encountered this problem yesterday afternoon, but the debugging was always successful, but the data was not updated. After searching on the Internet, there are still few such items, probably because the Access database is rarely used, or because

When reading the MongoDB GFS document, I learned how to store physical files, including large files. In order to deepen your impression, I wrote an example of uploading files to Mongodb. Of course, since it is stored in the document database, you

Because the development project is based on the project developed by a third-party company, the database is directly dependent, and the relationship between the project source code developed by the company and the database table is unknown, the

The process is like this! Add A record to Table A of the database. ** in the system, there will be 5 N more files under directory B. As the system has been running for more than three years, the number of files in directory B has reached more than 2

When the front-end time is used to migrate databases to others, some problems are encountered. Generally, if the backup database has EXTERNAL_ACCESS and UNSAFE assemblies, some strange errors may occur during the restoration process: Message 10314,

This article is a set of effective systems summarized by the author in years of ORACLE Database management work. It greatly improves the work efficiency, so as to predict the potential risks of the database in advance and eliminate them as soon as

To configure TRANSPARENT GATEWAY FOR SYBASE 1. Install sybase client on the server where oracle is located (or install oracle and sybase servers on the same server) to ensure that the sybase database can be accessed; 2. Install the transparent

To achieve maximum performance, databases generally have a concurrency mechanism, but the problem is Data Access conflicts. To solve this problem, most databases Use Data Locking. There are two methods to lock data: Pessimistic lock and optimistic

At the same time, the increase in the number of online traffic is obviously difficult for servers with 1 GB of memory. In severe cases, even the server crashes every day or gets stuck from time to time. This problem has plagued me for more than half

Environment: oracle10g, operating system 5.2The database system is under rootvg/oracle File SystemThe data file is under datavg/oradata File SystemThe control file is under $/ORACLE_HOME/dbs/AND/oradata.Redo log files in

Introduction In today's society, various Lottery activities are quite common. The basic principles and main features of lottery activities are random. However, there is still a relatively balanced problem for lottery activities within a group, the

1. DBWR Process: This process writes the buffer to a data file. It is an Oracle background process responsible for Buffer Storage zone management. When a buffer in the buffer zone is modified, it is marked as "dirty". The main task of DBWR is to

1. First, check the name and file of the tablespace. select tablespace_name, file_id, file_name,round(bytes/(1024*1024),0) total_spacefrom dba_data_filesorder by tablespace_name; 2. Add data files alter tablespace users

A table connection refers to the association between tables in an SQL statement to retrieve relevant data from one or more tables, in general, the table and table connections can be divided into four types: equal connection, external connection,