Oracle

1. Display current user index information (dba_indexes,all_indexes,user_indexes) 03:41:37 sql> Select Index_name,index_type,uniqueness 03:41:49 2 from User_indexes; Index_name Index_type Uniquenes --------------- --------------- ---------

When you activate a constraint using the Enable VALIDATE option, the error message is prompted if the data already exists that does not meet the constraint rule, and the activation constraint fails. The existing data must be corrected at this time,

1, prohibit the restriction 04:55:47 sql> ALTER TABLE t1 disable novalidate constraint; Table altered. 04:55:48 sql> Select Constraint_name,constraint_type,status,table_name from user_constraints 04:56:03 2 where table_name= ' T1 ';

One, what is redo LOG The Redolog file is a very important document that records all changes to Oracle and is the most critical component of the database instance recovery mechanism. Sys@ocm> select * from V$log; group# thread# sequence# BYTES

1. The function and influence of the lock Locks are one of the core mechanisms for Oracle to manage concurrent access to shared database resources and to prevent "mutual interference" between concurrent database transactions. When the application

Oracle range partition Table already has a maxvalue partition, how do I add a partition? You cannot delete the data in the MaxValue partition without affecting the online application. 1, create a partition tableSql> CREATE TABLE P_range_test2 (ID

Calling Java program segments in stored procedures Software Environment: 1. Operating system: Windows Server 2. Database: Oracle 8i R2 (8.1.7) for NT Enterprise Edition 3, Installation path: C:\ORACLE Implementation method: 1, create a file

DB file Scattered read For frequently accessed tables, if an index is not indexed or an appropriate index is not established, Oracle can only scan it for a full table, resulting in a large number of waiting events. When a full table scan, the data

The following four SCN are primarily present within Oracle 1. Systems checkpoint (System checkpoint) SCN Each time a checkpoint completes, Oracle records the SCN corresponding to the checkpoint in the control file and can view the checkpoint SCN

The purpose of Flashback Before there is a flashback, if you are wrong to operate the data and have submitted, then want to return to the wrong operation, it will be a very troublesome thing. One might say that backup can be restored to the wrong

Stream is an extended application of Oracle's Message Queuing (also known as Oracle Advanced Queue) technology. Oracle Message Queuing resolves event management through publish/subscribe. Stream replication is just a data sharing technique based on

Below I introduce three kinds of view parallel related content, such as parallelism, parallel execution instance and so on through the experiment. 1, V$pq_tqstat view – Script [Oracle@rac1 ~]$ Cat Showdop.sql Column Server_type format A15

First, view the user index in the system table In Oracle, the system table is created automatically when the database is installed, containing all of the database's data dictionaries, the definitions of stored procedures, packages, functions, and

A bare device, also called a bare partition (raw partition), is a special character device that is not formatted and is not read by UNIX through a file system. This article collects the bare devices and Oracle Quiz 20 cases. 1. What is called the

In an Oracle database, creating an index is relatively straightforward. However, it is more difficult to create indexes reasonably. The author believes that when creating an index, it is three appropriate to create an appropriate number of indexes

Components of Oracle Architecture Oracle architecture includes a number of basic components we'll cover them in more detail below. 1, Oracle Server: Oracle server contains a variety of file structure, process structure and memory structure, but

In Oracle databases, a set of default user operating environments is provided. The number of rows fetched from the database once, such as when a user queries, the separator between columns, the maximum width per line, the number of rows by default

Before running the example of this article, record the INSERT, delete, update, and so on of the current datasheet, and make a backup of the date of operation, the operator, the original data, and now the data so that you can recover from the current

I/O includes two parts, read and write, to introduce the generation of write operations in Oracle databases first. 2.1. Write Before introducing write operations, simply look at the physical structure of Oracle: Oracle's physical files include the

The last time you talked about installing Oracle under Linux, you can use NETAC to configure the local naming of remote databases after installation. To connect Oracle databases under Perl, you must first install DBI and DBD for Oracle. Here's a