Oracle

Memory Structure and dynamic memory management memory are important factors affecting database performance. Oracle8i uses static memory management, that is, the SGA is configured in parameters in advance, and the database is internally allocated

Chapter 4: Index     1.creating function-based indexes     sql> create index summit.item_quantity on summit.item(quantity-quantity_shipped);     2.create a b-tree index     sql> create [unique] index index_name on

Q. 1: When will the rollback information applied in the event of a database crash　　 1. before the crash occurs 2. after the recovery is complete 3. immediately after re-opening the database before the recovery 4. roll back infrmation is never

Oracle connection Configuration Structure There are three connection structures for Oracle databases:1) Combination of user and server structure: In this connection mode, the client and server are in the same machine. For each user, the library

Chapter 8: managing password security and resources     1.controlling account lock and password     sql> alter user juncky identified by oracle account unlock;     2.user_provided password function     sql> function_name(userid in varchar2

Oracle Database startup and Shutdown I. Start data$ Sqlplus "sys/pass as sysdba"SQL> startup Ii. Start the listenerAfter the database is started, if the listening process is not started, the client cannot connect to the database. The method for

Q. 1: Physical Disk Resources in an Oracle Database are 1. Control Files2. Redo Log Files3. Data Files4. All of the above 4 　　Q. 2: What is a Schema1. A Physical Organization of Objects in the Database2. A Logical Organization of Objects in the

Q. 1: Oracle immediately re-uses the space assigned to row-directory portion of the data block once you delete the corresponding rows.　　 1. True 2. False 　　 2 　　　 　　 Q. 2: Which of the following three portions of a data block are collectively called

Q. 1: What option of Exporting allows quicker data extractions 1. Grants = y2. Consistent = y3. Direct = true4. Direct = y 4: Direct = y option bypasses the SQL layer to allow quicker data extractions 　　Q. 2: How are exports useful?1. Can be used

Oracle Permissions 1. Permission OverviewPermission is the user's power to execute a function. In Oracle, permissions are divided into system permissions and entity permissions based on different system management methods. System permission refers

The physical structure of oracle is in a server, and each running database has a database instance (instancename. When the database is started, the system first allocates the system global zone (SGA) in the server memory, which constitutes the

Q. 1: What system privilege is required to create a rollback segment?　　1. Create database 2. Create rollback segment 3. Alter database 4. Create segment 　　 2 　　　 　　 Q. 2: Oracle recommends this number of minimum extents in a rollback segment 　　 1. 0

Oracle parameter file (1) Chapter 3 In oracle databases, parameter files contain all database configuration information, which is very important. I think that if you want to manage oracle well, you must be well aware of the parameters

Step 1 Preparation ? Check memorySZ_TOMCAT:/home/xjy/soft> grep SwapTotal/proc/meminfoSwapTotal: 2031608 kB ? Check the kernelLinux reaky.com 2.6.9-5. ELsmp #1 SMP Wed Jan 5 19:30:39 EST 2005 i686 i686 i386 GNU/Linux ? Check the Software

36.Use UNIONReplace OR (Applies to index columns) In general, replacing OR in the WHERE clause with UNION will produce better results. using OR for index columns will scan the entire table. note that the preceding rules are only valid for multiple

A corrupted data file, how to open the database -- ORA-01033: ORACLE initialization or shutdown in progress Error System Environment:1. Operating System: Windows 2000 Server, 128 MB of machine memory2. Database: Oracle 8i R2 (8.1.6) for NT

25.Improve efficiency with indexes   An index is a conceptual part of a table to improve the efficiency of data retrieval. in fact, ORACLE uses a complex self-balancing B-tree structure. data Query by index is usually faster than full table scan.

27.Basic table Selection   Driving Table is the first Table to be accessed (usually accessed in full Table scan ). depending on the optimizer, the selection of basic tables in SQL statements is different. If you are using the CBO (cost based

43.Use WHEREReplace ORDER The order by clause only uses indexes under two strict conditions.   All columns in order by must be included in the same index and maintained in the ORDER of the index. All columns in order by must be defined as non-empty.

46.Connect multiple scans If you compare a column with a limited set of values, the Optimizer may perform multiple scans and merge the results. Example: SELECT * FROM LODGING Where manager in ('bill Gates', 'Ken muller ');   The Optimizer may