Oracle

The cost calculation for the early Oracle query optimizer is based on the physical reading required to execute the SQL statement, which is called the I/O overhead mode (I/O cost model), and the main disadvantage of this method is that the Stompbox

1. SqlplusSqlnet.ora file Format names.directory_path= (tnsnames,hostname). The client will first find the ORCL record in the Tnsnames.ora file. If there is no corresponding record then try to ORCL as a hostname, through the network to resolve its

First, export/import (Export/import)----Use export to extract data from the database and import the extracted data back to the Oracle database. ----1. Simple Export data (exports) and imported data (import)----Oracle supports three types of output:--

DECODE (condition, value 1, return value 1, value 2, return value 2,... Value N, return value N, default value)DECODE (field or Field operation, value 1, value 2, value 3)The result of this function is that when the value of the field or Field

First, the client listens to the database by listening, the database opens a server process process to receive the SQL sent by the client.1. This SQL statement has never been executed. (Hard Parse)2. This SQL statement has been executed. (Soft

It seems that some people still do not understand the true meaning of the schema, and now I have to tidy up a bit, I hope to be helpful to everyone.Let's start by looking at their definition:ASchemais a collection of the database objects (used by a

1. What is block corruption:The so-called corrupted block of data is that the block is not in the recognizable Oracle format or its contents are internally inconsistent. Typically, corruption is caused by a hardware failure or an operating system

For example, we want to create an index for the geometry field of base_passenger_station. The specific statements are as follows. INSERT into User_sdo_geom_metadata (table_name,column_name,diminfo,srid) VALUES (' base_passenger_station ', ' GEOMETRY

Often use the database, let him start the words, the boot is too slow, so use the command to start a convenient point. 1. On: Enter CMD in the run, enter the console, Lsnrctl start Enter, prompt to start monitoring successfully after net start

Awr Basics1. Automatic Working Load WarehouseOracle collects a large amount of statistical information about performance and motion. This information accumulates in memory and is written regularly to the disk (that is, to the table that makes up the

Oracle has been in use for a long time, adding many user and tablespace. Need to clean up. For a single user and tablespace, you can do this using the following command. Step One: Delete user Drop Userxxcascade Note: Delete the user, just delete the

The Oracle Wm_concat (column) function allows us to use it frequently, and below teaches you how to use the Oracle wm_concat (column) function to implement a field merge if you have an Oracle Wm_concat ( column) If you are interested in using the

Oracle table Connection was asked, feel the details are still far from enough ah, from the Internet to find information to learn. Reproduced.In the ViewSQLWhen we execute the plan, we find that there are many ways to connect tables, and this article

--1. querying for locked casesSelect object_name,machine,s.sid,s.serial#from v$locked_object l,dba_objects O, v$session s where l.object_id = o.object_id and L.session_id=s.sid; --2. kill The process of losing a deadlock alter system

Check the information you need to focus on within two days:VI alter_error.shecho "Check Alter Error:" Cat $TRACE/alert_$oracle_sid.log | GREP-E ^ora-\| reconfig\|abort\| shut\|^start\|error\| instance\| suspend\| resuming\| Deadlock\| " ' Date '

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Oracle database We are all familiar with the fact that there is a very common data type in the database: string type. For the supposed type, there are three more commonly used types in Oracle: VARCHAR2 (Byte), varchar2 (char), NVARCHAR2 (). So

ObjectiveWhen I used to do the project, I seldom paid attentionComparison of knowledge pointsdetails of the thing, just right today to have this opportunity, the Oracle in a few common functions to distinguish. Grammar Delete from

Use commands to create an oracle11G Database This document describes how to create an oracle database that complies with the OFA specification using the create database Command of the oracle database. 1. Set the environment variable (vi.

Oracle Performance Analysis 10: Re-indexing-common SQL The previous section describes the causes and methods for re-indexing. This section describes several common SQL statements and stored procedures.Query all invalid global indexes select