INTRODUCTION TO ORACLE

Lynnwood BrownPresident System Managers LLC

Data Loading & Backup And Recovery Lecture 5

Copyright System Managers LLC 2003 all rights reserved.

DATA LOADING

Use the EXPORT/IMPORT utilities to move bulk data from one Oracle database into another Oracle database.

• Logical backup – Saves the data and the DDL used to create the database objects

• Migration Tool

• Online documentation - C:\> exp{imp} help=y

Data can also be loaded using SQL*PLUS “INSERT” commands or the Oracle utility SQL*LOADER.

DATA LOADING

Types Of Exports.

• Full Export– EXP system/manager file = exp.dat full = y log =

exp.log

• User Level Export– EXP system/manager file = exp.dat owner = scott log =

exp.log

• Table Level Export– EXP scott/tiger file = exp.dat TABLES=(emp,dept) log

= exp.log

DATA LOADING

Types Of Imports.

• Full Import– IMP system/manager file = exp.dat full = y log =

imp.log commit = y

• User Level Import– IMP system/manager file = exp.dat fromuser=scott

touser=scott log = imp.log commit = y

• Table Level Import– IMP scott/tiger file = exp.dat TABLES=(emp.dept) log

= imp.log commit = y

DATA LOADING cont.

SQL*LOADER - Oracle utility used to load external file data into Oracle database tables

• Used when large amounts of data must be loaded.

• Loads data contained in a data file into one or more tables

• Requires a SQL*LOADER control file

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DATA LOADING cont.

SQL*LOADER Syntax:

C:\> sqlldr scott/tiger control=my_control_file.ctl log=my_load.log

Data File Contents – file name = ubs.dat

930|1058|Edward S.Eng|ibm 931|2157|John Ford|hp932|1457|Melanie Goldman|msft933|1657|Jane Williams|dell

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DATA LOADING cont.

SQL*LOADER Control File – Tells the loader how to how to interpret the data file:

LOAD DATAINFILE 'ubs.dat'BADFILE 'ubs2.bad'DISCARDFILE 'ubs2.dsc'APPENDINTO TABLE ubs.table_customerFIELDS TERMINATED BY '|'OPTIONALLY ENCLOSED BY '"'TRAILING NULLCOLS(CUST_NO, SITE_NO, CUST_NAME ,SITE_ ABBREV)

DATA LOADING cont.

SQL*LOADER Control File – Tells the loader how to load the data:

• INFILE – File containing the data to be loaded

• BADFILE – Records that are rejected go into this file

• DISCARDFILE – Records that do not meet a loading criteria

Data can be appended onto existing data, inserted or replaced - APPEND/INSERT/REPLACE

DATABASE BACKUP

Used if the database needs to be recovered due to a hardware or end user created failure. Types of database backups include:

Logical Backup – Uses IMPort/EXPort. Often used to recover dropped tables. Saves the data.

Physical Backup – Used to recover the database from hardware failures. Saves the databases data files. Either COLD or HOT.

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DATABASE MODES

• Database is running in ARCHIVELOG mode

• When the active log file becomes filled a log switch is signaled

• LGWR process switches to writing to the next log file

• The ARCH process saves the active log file to offline storage

SGA

ARCHLGWR

DataRedo LogFiles

Data

ArchivedRedo Log

Files

OnlineStorage

OfflineStorage

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DATABASE BACKUP

Cold physical backup - Backup that is taken when the database is shutdown.

• Save data files, log files and control files.

• How to find the location of the files:

SQL > select member from v$logfile;SQL > select file_name from sys.dba_data_files;SQL > select name from v$control_files;

DATABASE BACKUP cont.

Hot backup - Backup taken while the database is up (end users can also access the database during the backup).

• Requires that the database be run in ARCHIVELOG mode – Check v$database

• Redo log files are moved to offline storage when they fill up.

• Redo log files are moved to offline storage by the ARCH process.

DATABASE BACKUP

• DBA needs to monitor the offline storage to make sure that it does not fill up.

• Save “archived log files” using OS copy command.

• Delete archived log files from the archive directory.

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DATABASE BACKUP

• Save tablespace data files using “ALTER TABLESPACE BEGIN/END BACKUP” AND OS copy command.

• Save database control file by using the ‘ALTER DATABASE BACKUP CONTROLFILE “ command.

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DATABASE BACKUP

• Save The data files:SQL > alter tablespace system begin backup;

SQL > HOST copy c:\oracle\system01.dbf C:backup

SQL > alter tablespace system end backup;

SQL > alter database backup controlfile to ‘c:\backup\control_backup.ctl';

SQL > alter system switch logfile;

SQL > quit

• Save ARCHIVELOG files

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DATABASE RECOVERY

• Recovery using a cold backup. Restore data files, log files and the control files to their original location.

• Startup the database.

• System is recovered to the last cold backup.

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DATABASE RECOVERY cont.

• Recovery using a hot backup. Recovers the database to the point in time of failure.

• Requires access to both online and offline log files.

• After issuing either RECOVER DATABASE, RECOVER TABLESPACE or RECOVER DATAFILE the Oracle recovery management will prompt for the locations of the archivelog files.

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DATABASE RECOVERY cont.

• Oracle recovery process uses the contents of the control file to determine which ARCHIVELOG files are required for the recovery

• The SMON process will:

– Perform roll forward recovery using the data in the log files.

– Perform rollback recovery by applying the data from the rollback segments to UNDO uncommitted changes

DATABASE BACKUP

• Recovery Manager (RMAN) is an Oracle utility introduced in Oracle8

• RMAN types of physical database backups: 

– Block level backup and recovery– Hot and cold backups– Full and incremental backups

• Optional recovery catalog

DATABASE BACKUP – Recovery Manager

Ethernet

Production Server

Database Files

Data FilesLog FilesControl FilesArchived Log Files

Tape Drive

RMAN Catalog Server(optional)

RMAN Catalog

DATABASE BACKUP

RMAN can be used with or without a recovery catalog. If no recovery catalog is used then all information required for recovery is obtained from the databases control files.

Connecting to RMAN with a recovery catalog:

rman target sys/manager123 rcvcat rman/rman@cat_alias

Connecting to RMAN without a recovery catalog:

rman target sys/manager123 nocatalog

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DATABASE BACKUP

• RMAN Backup Script:

run { allocate channel dev1 type disk; backup incremental level 0 tag = 'full backup' database include current controlfile format = 'c:\rbackup\db_t%t_s%s_p%p'; sql "alter system switch logfile"; backup format = 'c:\rbackup\ar_t%t_s%s_p%p' archivelog all; release channel dev1; } exit

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DATABASE RECOVERY

• RMAN Recovery Script:

run {

allocate channel dev1 type disk;

alter database mount;

restore database;

recover database;

sql "ALTER DATABASE OPEN RESETLOGS";

}

 

exit

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DATABASE BACKUP/RECOVERY

To run an RMAN script from the command prompt:

c:\> rman target sys/not4u cmdfile c:\scripts\backup\hot_rman_bkup_lvl0.rcv msglog c:\rbackup\current_rman_lvl0.log nocatalog

TARGET – Use the current setting for ORACLE_SID as the database to be backed up.

 CMDFILE – RMAN script that is used to backup the database MSGLOG – File where messages that are written during the time of backup are

written NOCATALOG – Tells RMAN that this backup is being performed without a

recovery catalog