Oracle FAQs Questions with Answers # 9

How does one put a database into ARCHIVELOG mode? (for DBA)

The main reason for running in archivelog mode is that one can provide 24-hour availability and guarantee complete data recoverability. It is also necessary to enable ARCHIVELOG mode before one can start to use on-line database backups. To enable ARCHIVELOG mode, simply change your database startup command script, and bounce the database:

SQLPLUS> connect sys as sysdba
SQLPLUS> startup mount exclusive;
SQLPLUS> alter database archivelog;
SQLPLUS> archive log start;
SQLPLUS> alter database open;

NOTE1: Remember to take a baseline database backup right after enabling archivelog mode. Without it one would not be able to recover. Also, implement an archivelog backup to prevent the archive log directory from filling-up.

NOTE2: ARCHIVELOG mode was introduced with Oracle V6, and is essential for database point-in-time recovery. Archiving can be used in combination with on-line and off-line database backups.

NOTE3: You may want to set the following INIT.ORA parameters when enabling ARCHIVELOG mode: log_archive_start=TRUE, log_archive_dest=... and log_archive_format=...

NOTE4: You can change the archive log destination of a database on-line with the ARCHIVE LOG START TO 'directory'; statement. This statement is often used to switch archiving between a set of directories.

NOTE5: When running Oracle Real Application Server (RAC), you need to shut down all nodes before changing the database to ARCHIVELOG mode.

What is the basic data structure that is required for creating an LOV?

Record Group.

How does one backup archived log files? (for DBA)

One can backup archived log files using RMAN or any operating system backup utility. Remember to delete files after backing them up to prevent the archive log directory from filling up. If the archive log directory becomes full, your database will hang! Look at this simple RMAN backup script:

RMAN> run {
2> allocate channel dev1 type disk;
3> backup
4> format '/app/oracle/arch_backup/log_t%t_s%s_p%p'
5> (archivelog all delete input);
6> release channel dev1;
7> }

Does Oracle write to data files in begin/hot backup mode? (for DBA)

Oracle will stop updating file headers, but will continue to write data to the database files even if a tablespace is in backup mode.

In backup mode, Oracle will write out complete changed blocks to the redo log files. Normally only deltas (changes) are logged to the redo logs. This is done to enable reconstruction of a block if only half of it was backed up (split blocks). Because of this, one should notice increased log activity and archiving during on-line backups.
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Set 4

What is the Maximum allowed length of Record group Column?

Record group column names cannot exceed 30 characters.

Which parameter can be used to set read level consistency across multiple queries?

Read only

What are the different types of Record Groups?

  • Query Record Groups
  • NonQuery Record Groups
  • State Record Groups
  • From which designation is it preferred to send the output to the printed? 
  • Previewer
What are difference between post database commit and post-form commit?

Post-form commit fires once during the post and commit transactions process, after the database commit occurs. The post-form-commit trigger fires after inserts, updates and deletes have been posted to the database but before the transactions have been finalized in the issuing the command. The post-database-commit trigger fires after oracle forms issues the commit to finalized transactions.

What are the different display styles of list items?

Pop_listText_listCombo box

Which of the above methods is the faster method?

Performing the calculation in the query is faster.

With which function of summary item is the compute at options required?

Percentage of total functions.

What are parameters?

Parameters provide a simple mechanism for defining and setting the valuesof inputs that are required by a form at startup. Form parameters are variables of type char,number,date that you define at design time.

What are the three types of user exits available?

Oracle Precompiler exits, Oracle call interface, NonOracle user exits.

How many windows in a form can have console?

Only one window in a form can display the console, and you cannot change the console assignment at runtime.

What is an administrative (privileged) user? (for DBA)

Oracle DBAs and operators typically use administrative accounts to manage the database and database instance. An administrative account is a user that is granted SYSOPER or SYSDBA privileges. SYSDBA and SYSOPER allow access to a database instance even if it is not running. Control of these privileges is managed outside of the database via password files and special operating system groups. This password file is created with the orapwd utility.

What are the two repeating frame always associated with matrix object?

One down repeating frame below one across repeating frame.

What are the master-detail triggers?

On-Check_delete_masterOn_clear_detailsOn_populate_details

How does one connect to an administrative user? (for DBA)

If an administrative user belongs to the "dba" group on Unix, or the "ORA_DBA" (ORA_sid_DBA) group on NT, he/she can connect like this:

connect / as sysdba
No password is required. This is equivalent to the desupported "connect internal" method.
A password is required for "non-secure" administrative access. These passwords are stored in password files. Remote connections via Net8 are classified as non-secure. Look at this example:
connect sys/password as sysdba

How does one create a password file? (for DBA)

The Oracle Password File ($ORACLE_HOME/dbs/orapw or orapwSID) stores passwords for users with administrative privileges. One needs to create a password files before remote administrators (like OEM) will be allowed to connect.

Follow this procedure to create a new password file:

  • Log in as the Oracle software owner
  • Runcommand: orapwd file=$ORACLE_HOME/dbs/orapw$ORACLE_SID password=mypasswd
  • Shutdown the database (SQLPLUS> SHUTDOWN IMMEDIATE)
  • Edit the INIT.ORA file and ensure REMOTE_LOGIN_PASSWORDFILE=exclusive is set.
  • Startup the database (SQLPLUS> STARTUP)
NOTE: The orapwd utility presents a security risk in that it receives a password from the command line. This password is visible in the process table of many systems. Administrators needs to be aware of this!

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