Database Admin Interview Questions

In case of hot backup we get fractured blocks, because of this reason hot backups is called Inconsistent backup. let say in hot backups our operating system copies OS block by OS block while copy is g...

The concept of fractured block occrus when backup is under process.
It means you are taking backup and some other session is updating it.
Then backup process can not get the consistent image of the block and it will be inconsistent right thats why it is called fractured block.

Querying views like rc_database in each catalog will identify the target database it is registered with.

There are few ways through which you would find if your database uses recovery catalog: Check backup scripts and findout if the scripts are making any connection to a recovery catalog. Check tnsnames...

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| | | | |
| | | | +----- Day of week (0-6)
| | | +------- Month (1 - 12)
| | +--------- Day of month (1 - 31)
| +----------- Hour (0 - 23)
+------------- Min (0 - 59)

Backup can be taken in 3 ways 1)Cold backup 2)Hot Backup 3)RMAN Backup 1)For taking cold backup we need to shutdown database.So it is not advisable 2)Hotbackup can be taken while the DB upon running...

DDL is Auto Commited Statements.

There is no need to issue commit command after executing DDL statements as the DDL statements are commited automatically

I will refer predominantly to Relational DBMS. In a file system, data is contained in a flattened structure that is often a variable length structure. For example, a shipment received could contain th...

DDL is used to create, alter and truncate
DML is used to insert, update, delete and drop

DDL means "Data Definition Language". SELECT, UPDATE, INSERT belong to DML, which is "Data Modification Language". DDL is all the other commands -- for example, CREATE TABLE.

Alter table A add column address1 varchar2(10);

Unsing Pivot Query

You can make use of VSIZE function to get the number of bytes in the internal representation of individual field. However this cannot be applied on fields that has BLOB data type and in such case you have to use dbms_lob.getlength function on BLOB data type field.

Online backup also known as hot backup / open backup can be performed even the database is open and while users are working and is available for read and write activity. To perform Online backup, the ...

SORT_AREA_SIZE is one of the deferred Oracle Server Parameters which is set in init.ora. Its value as bytes (integer) sets the size of in-memory sort work area. The default is 64K and the maximum valu...

Yes We can Take of Controlfile Online Mode Just
Fire The Command alter database backup controlfile trace And
alter database backup controlfile as trace '/Location where u want 2 take backup of ctlfile/';

No, we can not take backup of redo log files even database is running in archive log mode because of inconsistency

just create the datafile with same location mention in ur controlfile and recover the datafile ... Its simple.

alter database create datafile 'and give the datafile location and /name' by using this command we can recover the datafile without backup also

show sga;

we can see the memory of SGA space

Whats the process of refresh ? ( I mean steps). Do you export/import or we take a differential backup and restore on test DB ? Any links to an article will be of great help.

Hi, There is little diff between them. First we clone the d.b totally(homepath,datafiles,data.....etc) from Prod to Test, where as in D.B Refresh we just refresh the additional data which is in p...

1- When BEGIN BACKUP is issued: The hot backup flag in the datafile headers is set, so that the copy is identified to be a hot backup copy. This is to manage the backup consistency issue when the cop...

Sql>alter database begin backup;The above query is used to freeze the header of all datafiles belongs to tablespace in that particular database.Freeze means lock i.e during backup no data's wil...