Oracle

When does an instance recovery occur? When your database server is powered down abnormally, an instance recovery occurs when you restart the database. Instance recovery is done automatically by the database without the intervention of the DBA. Of

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

1, the column to row, the following data ID NAME ---------- ------------------------------ Ten AB bc Ten CDs Hi ij Mn 6 Rows selected 2. Call Oracle's function Sql> Select Id,wmsys.wm_concat (name) name from IDTable 2 Group by ID; ID NAME ---------

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

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

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

Statspack Installation Use and analysis 1. View table Space Select Tablespace_name,file_name from Dba_data_files; 2. Create Statspack table Space Create tablespace perfstat datafile ' d:\oracle\oradata\perfstat.dbf ' size 500m The table space

The database was found to be slow today, and a large number of processes are waiting for log file switch (checkpoint incomplete), and log files are used as follows: sys@test15>select group#,sequence#,bytes/1024/1024 "bytes (M)", Members,archived,

Partition add The new partition can only be added to the end, and if you need to add partitions to the front or center, you need to use partition splitting. ALTER TABLE p95169.order_info Add PARTITION pmax VALUES less THAN (MAXVALUE) tablespace

1. Definition Triggers: associated with a table or database event, a trigger defined on a table triggers execution when a trigger event occurs. Trigger Trigger Order 1 execute BEFORE statement level trigger; 2 for each row affected by the

Oracle Partial Recovery method We sometimes need to do a recovery test, however, because the target database is too large, if the full recovery of data files, then need a lot of storage space, but if not to do the recovery test, and how the