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What is a redo log
imran44
- Jul 10th, 2009
At the time of database creation 2 redo log files are created, these redo log files act in circular fashion, when log switch occur, redo log file will dump its contents in archived log destination, an...
nagabhushan reddy
- Feb 8th, 2006
Redo log file contains data which changes made to the database.it is used for recovery purpose.
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What is a database instance and Explain
imran44
- Jul 10th, 2009
SGA+Background Process = InstanceAs soon as user process starts and server process takes control from user process, instance created with help of background processes and most important background pro...
cmanne
- Jan 4th, 2006
An Oracle instance is a combination of background processes and memory structures (SGA)
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Recover corrupted database
If the entire disk is corrupted how will you recover the database and what are the steps to recover the database?
m4k4v3l1
- Jul 1st, 2009
Things Useful For Complete Recovery :1- Last Valid Backup2- Dump Files3- Archive Logs- If You Have a Valid Backup on Another Disk Rather Than The Damaged One , You Can Recover The Database till The Ti...
kalpeshbanokar
- Jul 24th, 2008
Succesful backup is possible iff there is "Archive Mode" is on.that is database is in Archive Mode.and if it's offthen there are only 99.9% chancesthroughGroup1 or Group2 of Online Redo log files.
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Oracle memory segments
How do you see how many memory segments are acquired by Oracle Instance.
olilogu
- May 11th, 2009
Check on x$bh it show you what objects are in the buffer.Try this query;SELECT /*+ ordered use_hash(o) use_hash(bh) */ bp.NAME BUFFER_POOL, ...
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Oracle Datafiles limit
How do you control No. of Datafiles one can have in an Oracle Database.
olilogu
- May 11th, 2009
At creation time you can set up the maximun numer of datafiles.CREATE DATABASE .....MAXDATAFILES 500If you want to check it:select * from V$CONTROLFILE_RECORD_SECTION where type ='DATAFILE';If you want to increase it, you have to recreate control file.
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Limit and Default size of Tablespace
Can we create as many tablespace as we require. What is the limit? What is the default size of tablespace? (System and User tablespace). Mention name of some tablespace.
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What is a public synonym
sivaraju.sateesh
- Apr 7th, 2009
Public synonym is a synonym which may not resodes in the owner schema.but it works as a same. to create public synonym we need special privileges
soccer_champ
- Jun 18th, 2005
A public synonym is owned by the special user group named PUBLIC and every user in a database can access it. In case of doubt, contact me : bobby_1020@hotmail.com
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What is a private synonym
Dan
- Jul 9th, 2005
To create a private synonym in your own schema, you must have CREATE SYNONYM system privilege. To create a private synonym in another user's schema, you must have CREATE ANY SYNONYM system ...
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What is a synonym
sivaraju.sateesh
- Apr 6th, 2009
Synonym is a alias name for an Oracle object. It can be simplified names to access the objects. Example of Synonym and how it is useful Employee is a table is HR Schema A user wants to access the...
waseemvnb
- Nov 12th, 2007
It is just like Aliasing .. ie giving some name in order to specicifically distinguish it....In other words to simplify the names of tables , column names etc it is used.. Suppose i have a column name...
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Can a view based on another view
sivaraju.sateesh
- Apr 6th, 2009
Yes a view can be based on another view. For example data dictionary views can be used to create another view in order to improve better access.
soccer_champ
- Jun 18th, 2005
Yes, a view can be based on another view.
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Oracle table space Quota and users
How to create User in Oracle, allocate quota on Oracle table space
shrikant2711
- Mar 28th, 2009
SQL> create user test identified by test default tablespace XYZ quota unlimited on XYZ1 quota unlimited on XYZ2 quota unlimited on XYZ3 quota unlimited on XYZ4;User created.
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How to convert local management tablespace to dictionary managed tablespace
amit19821
- Mar 13th, 2009
Local to Dictionary managed tablespcaes:exec dbms_space_admin.Tablespace_Migrate_FROM_Local('tablespace');Dictionary to locally managed tablespaces:exec dbms_space_admin.Tablespace_Migrate_to_Local('tablespace');
g.mrunalini
- Jul 22nd, 2008
Use the following package>execute dbms_space_admin.tablespace_convert_to_local('tablespace_name');>execute dbms_space_admin.tablespace_convert_from_local('tablespace_name');
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What are the fixed memory structures inside the SGA?
rajat_dua
- Mar 3rd, 2009
Part of the SGA contains general information about the state of the database and the instance, which the background processes need to access; this is called the fixed SGA. No user data is stored here....
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Estimate SGA Size
How to estimate the size of SGA?
rajat_dua
- Mar 2nd, 2009
SQL> show sgaTotal System Global Area 167772160 bytesFixed Size 1247900 bytesVariable Size 58721636 bytesDatabase Buffers 104857600 bytesRedo Buffers 2945024 bytes
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Mutated Trigger
What is mutated trigger? In single user mode we got mutated error, as a DBA how you will resolve it?
zodiac_som
- Mar 2nd, 2009
If you are using before in trigger block, then replace it with afterMutated error, when same table access?more than once in one state.
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ASE Server Performance
What will you do when the ASE server's performance is bad?
rajat_dua
- Mar 2nd, 2009
Bad performance" is not a very meaningful term, so you'll need to get a more objective diagnosis first. Find out (i) what such a complaint is based on (clearly increasing response times or ju...
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Oracle segments
How do you see how many memory segments are acquired by Oracle Instance.
Baipaneni
- Jan 23rd, 2009
For shared memory segmets in UNIX or LINUX:-->In HOST1_LINUX has one instance $ ipcs -m oracle@HOST1_LINUX:$ ipcs -m------ Shared Memory Segments --------key &nb...
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Monitor and Modify Data during Loading
How to monitor how fast a table is imported? How to modify data as it loads into the database?
Ramshankardba
- Jan 17th, 2009
Use below script to monitor how speed import is happening.SELECT SUBSTR(sql_text, INSTR(sql_text,'INTO "'),30) table_name, rows_processed, ROUND( (sysdate-TO_DATE(first_load_time,'yyyy-mm-dd hh24:mi:s...
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What is cluster key
imran44
- Jan 9th, 2009
The related columns of the tables in a cluster are called the cluster key. The cluster key is indexed so that rows of the cluster can be retrieved with a minimum amount of I/O.
Dan
- Jul 9th, 2005
A cluster index is needed in support of a cluster. One is used to allow the other to exist. Much like we need an index in support of a primary key. They are not the same things. Cluste...
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Can you change priority of a Process in Unix
jituoracle
- Jan 6th, 2009
Unix does provide the command nice [increment] command to lower a priority of a process. As system administrator you can use the renice command to change the priority of a process, all processes of a...
Oracle DBA Interview Questions
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