Oracle

1, the concept of the table Table is the basic unit of database data storage, it corresponds to the object of real world. 2, the function of the table Basic unit for storing and managing data (two-dimensional table: with rows and columns) 3, the

One, the database Management Section 1. Database replay (DB replay) This feature captures the load of the entire data and passes it on to a test database created from a backup or standby database, and then repeats the load to test the effect of

We already know that log buffers are used to store log information about the changes in transactions to the data block. So what is the content of the log information here, and what is the structure of it? The smallest unit of Oracle record database

Recently saw a lot of people talk about TNS or database can not log on issues, simply summed up the following document. First of all, Oracle's network structure, to complex to say can add encryption, LDAP and so on. There is no discussion here, and

Some people may not be accustomed to table names, fields are all capitalized, and prefer lowercase or case-mixed form, if so, you write the script in Oracle should pay attention to, not handled well, this will bring you "endless trouble." Create a

Date data type This data type is so familiar that we think of date types when we need to represent dates and times. It can store months, years, days, centuries, hours, minutes, and seconds. It is typically used to indicate when something has

This article describes the typical examples that sql*loader often use in the process of actual use. 1. How do I get fewer columns for the larger than data file in the table? Suppose a CSV file is as follows: A1,A2,A3,A4 b1,b2,b3,b4

Introduction Oracle is the most widely used large-scale database management system, improve the efficiency of Oracle database system, is the premise and guarantee of the efficient operation of the whole computer information system. There are many

Oracle developer is well known for its rapid data processing development, and its exception handling mechanism is also relatively perfect, not to be underestimated. 1, the advantages of the exception If there are no exceptions, in the program, you

Oracle Data Guard from the macroscopic point of view, mainly provides the following two services: 1) Log transmission: The main library transmits the generated redo log to the standby library; 2 log application: The redo log, which is transferred

To improve performance, we have tried a number of ways or scenarios that the Oracle database itself has provided, mainly including: Shared server mode (MTS); Cluster technology (clustering) RAC; Partition Parallel processing (mainly parallel

A view is a table that is exported from a table or view, or a table that is exported from more than one table or view. A view is a virtual table in which the database does not actually store the data that corresponds to the view, only the definition

The external table is the table structure that is stored in the data dictionary, and the table data is stored in the OS file's tables. By using an external table, you can not only query the data of the OS files in the database, but also use the

Two days ago, it was mentioned that the serializable isolation does not support the ability to delay segment creation and interval partitioning, and it is thought that because both of these methods are recursively generating DDL operations in DML,

Today, one of my buddies said that some of the modules in OA were invalid, check the system log, the original Oracle database temporary table space is full, noon meal time to the database restart (this way the easiest and not easy to make mistakes),

In real-world database applications, we often encounter the problem that a user who connects to an Oracle database does not have a subsequent operation after an operation, but is disconnected from the database for a long time. For a small

There are two ways to optimize Oracle's optimizer: Rule-based optimization method: rule-based optimization (RBO) Optimization method based on cost or statistic information (cost-based OPTIMIZATION:CBO) Rbo: When the optimizer analyzes SQL

1. RESTORE command Although the store command has some secondary targets, its main function is to restore files from the Rman backup to prepare for recovery. The Rman and restore commands are very limited, and they will select the most recent

Today a customer consults with their RAC environment, Emd_maintenance. The Execute_em_dbms_job_procs process starts frequently and consumes a lot of system resources. This task runs every minute, and it is always in front of the top. This job is

Check a system, accidentally found the database v$session_longops time far more than the system time. The results of the query are as follows: [ORACLE@DATASD ~]$ Sqlplus/as SYSDBA Sql*plus:release10.2.0.3.0-production on Monday December 20 14:57:0