Heena

• Sep 17th, 2017

Database writer process(DBWn)

sriram

• May 17th, 2016

DBWR is one of the BG processed of Oracle DB. It writes modifies the data in data base buffer cache

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When does the LGWR writes all redo-enteries to the redo-log buffer?

Suresh

• Oct 31st, 2017

1) When user hits commit
2) When there is 1/3rd full in redo log cache
3) One every 3 seconds

During this above situation LGWR writes redo log entries into redo log files from redo log cache !!

Mayur Pimpalkar

• Dec 24th, 2015

Lwgr process writes redo entries to online redolog files not to redobuffer.

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A data file can be associated with only one database. Once created a data file can't change size.One or more data files form a logical unit of database storage called a tablespace.

ranjithsv18

• Oct 2nd, 2013

Block size available from 2k,4k,8k,16k and 32k.

As per oracle point of view Default (or) standard block size is 8k for Data files.The initialization parameter

db_block_size=8k (8192)remaining size are non-standard blok size. Extents size 64k.

(Datafile

NAGARAJ OCP

• Dec 27th, 2011

In data files, we cant change the extent management, type of it. But we can change the storage space for it if we need after the database (tablespace) creation.

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sandeep

• Apr 26th, 2013

Ps -ef | grep oracle

chittu.kotian

 Profile Answers by chittu.kotian Questions by chittu.kotian

• May 16th, 2012

On Unix the command is ps -aef | grep -i pmon

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Prabhat Sahu

• Oct 21st, 2017

B-Tree Index:
1. Oracle Default index.
2. Cardinality is High, means less duplicate(more unique records) (i.e. Rowid)

Bitmap Index:
1. Cardinality is Low, means more duplicate.(most of the values are repetative)
2. Flag related columns ( i.e. M/F, Y/N, 1/0 )

Vineet

• Oct 12th, 2017

1. B-tree Index has high cardinality values, where as Bitmap Index has low Cardinality values.

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ranjithsv

• Oct 2nd, 2013

Its relation between SGA and 5 Mandatory Background process
SMON,PMON,DBWR,LGWR,CKPT

ARUN BHUKKER

 Profile Answers by ARUN BHUKKER Questions by ARUN BHUKKER

• Oct 19th, 2012

A background process maintain relationship between memory structure and physical structure of Oracle server. Started when Oracle instance is started. Consist of 5 mandatory and some optional backgro...

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Tablespaces and the Database's Schema Objects.

mosin

• Jan 18th, 2018

Tablespace
Segments
Extent

Heena

• Sep 17th, 2017

Tablespaces, Segments, Extent, Data blocks

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ORACLE database is comprised of three types of files. One or more Data files, two are more Redo Log files, and one or more Control files.

Naresh

• Feb 14th, 2018

Use DBMS_CRYPTO for encrypt and decrypt the objects

Harshad Khuspe

• Dec 27th, 2015

Components of Physical Databases are Oracle files which are in disk. i.e. Datafiles, Online Redolog files, Archive log files, Parameter file, Password File, Controlfile etc.

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A view is a virtual table. Every view has a Query attached to it. (The Query is a SELECT statement that identifies the columns and rows of the table(s) the view uses.)

pravesh28

 Profile Answers by pravesh28 Questions by pravesh28

• Mar 27th, 2010

View means virtualit is virtual table drived from base tableview doesnt contain any data view is mirrar image of data that we  can set the its size

C.Ramesh

• Oct 17th, 2007

View is a Virtual Table. It likes like a table. View provide additional level tabel security and providing selected columns only and it accessing different tables no need to joins of different tables. Views also stores data like (Materialized Views) it can be referesh methods like fast, complete.

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How does the SMON process performs recovery after instance failure?

ranjithsv18

• Oct 2nd, 2013

When hardware failure, software failue and shutdown abnormally happen... SMON taking care of Instance failure, coalesce failure space and deallocating temp segment start to recover instance Roll fw...

Nagaraj OCP

• Dec 27th, 2011

When shutdown abort happens, oracle server gets crashed. To recover from the crash, SMON will check the online Redo data files and last SCN no in the Redo log files and SCN number in the undo tablespa...

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Which parameter specifies the number of DBWn processes?

mosinpatel

• Jan 18th, 2018

SQL> show parameter db_writer_processes
NAME TYPE VALUE
------------------------------------ ----------- -------
db_writer_processes integer 1

srinivasarao

• Mar 22nd, 2015

DB_WRITER_PROCESS=""

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How we can determine the physical architecture of oracle?

ranjithsv

• Oct 2nd, 2013

Datafiles(*.dbf),
Controlfiles(*.ctl),
Redologfiles(*.log),
Archivelogfiles(*.arc)

ARUN BHUKKER

 Profile Answers by ARUN BHUKKER Questions by ARUN BHUKKER

• Oct 19th, 2012

Oracle architecture consist of four structures: 1. Memory structure (SGA, PGA) 2. Process structure (user process, server process, background process) 3. Physical structure (data files, redo log files...

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What is high watermark in oracle ?

Prabhat Sahu

 Profile Answers by Prabhat Sahu Questions by Prabhat Sahu

• Oct 15th, 2018

-- High Level Watermark: ------------------------- --> HLW is a term used with table segment in DB to show the amount of datablock occupied(level) by the table data. --> As per PCTUSED and PCTFREE ...

Prabhat Sahu

• Oct 4th, 2017

-- High Level Watermark: ------------------------- --> HLW is a term used with table segment in DB to show the amount of datablock occupied(level) by the table data. --> As per PCTUSED and PCTFREE ...

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What is the difference between log sequence number and checkpoint id? How it is used for instance recovery?

vishal gajage

• Jun 21st, 2017

Log Sequence Number is assigned to every redo log file after full the redo log file....and SCN number is generated after every commit

aditya verma

• May 11th, 2017

Logs sequence no is the value which is mention in header of every datafile. Below is the situations when SCN changed.
After every commit the transaction.
Log switch.
Backup completion.

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A database link is a named object that describes a "path" from one database to another.

Vinod Karuturi

• Nov 16th, 2015

A database link is a schema object in one database that enables you to access objects on another database. The other database need not be an Oracle Database system. However, to access non-Oracle systems you must use Oracle Heterogeneous Services.

Madhu Alampalli

• Sep 24th, 2015

Cluster key is a related column of tables in the cluster. For example, in Table EMP which has (EMP NO, EMP NAME, DEP NO, etc ) and DEPT which has (DEPT NAME, DEPT NO etc), DEPT NO is the cluster key in this cluster.

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sanjayoracle

 Profile Answers by sanjayoracle Questions by sanjayoracle

• Apr 25th, 2008

Just in simple words.....Ora01555 error occurs when a transation fails when it cannot able to find read consistence image in rollback segment. To solve this problem: Increse the Undo_RetentionCheers :)

Mohammed Abdul Afroze

• Mar 25th, 2007

Answer: Avoiding Snap Shot too old error-(oerr ora 01555).   First thing here we understood how is the rbs works.This will work in circular fashion by looping around the reuse of the ex...

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Each Non-clustered table has a data segment. All of the table's data is stored in the extents of its data segment. Each cluster has a data segment. The data of every table in the cluster is stored in the cluster's data segment.

Harshad Khuspe

• Dec 27th, 2015

Tablespace is made up of Segment. Segment is made up of extents and extents are made up of contiguous oracle blocks. Segments are nothing but a table. i.e. Table Emp is nothing but segment emp. You can check things from data dictionary view DBA_Segments.

pradeep

• May 5th, 2015

A data segment is a set of extents allocated to a certain logical structures

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SID (System Identifier)  :  A SID (almost) uniquely identifies an instance.  Actually, $ORACLE_HOME, $ORACLE_SID and $HOSTNAME identify an instance uniquely. The SID is 64 characters, or less; at least on Oracle 9i. The system identifier is included in the CONNECT_DATA parts of the connect descriptors in a tnsnames.ora file. The SID defaults to the database name. Global Database Name...

pavan

• Jul 4th, 2017

Can a database name can be same across multiple instances, and can the instances number be same? If yes what is SID in that case?

shaikhannan

 Profile Answers by shaikhannan Questions by shaikhannan

• Feb 3rd, 2010

SID = identifies the database instance (database name + instance number). So if your database name is somedb and your instance number is 3, then your SID is somedb3. DB Name = Name of the database (d...

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mmaz2002

 Profile Answers by mmaz2002 Questions by mmaz2002

• Jul 15th, 2009

All Extent info is maintained in Dictionary which is infact a dis-advantage, Also in case of a huge insert operation undo is generated.

deep chandan

 Profile Answers by deep chandan Questions by deep chandan

• Dec 30th, 2008

The main advantage of using dictionary managed tablespaces is that in this we can give the size of the extents according to our need. We can modify extent size but in locally managed tablespace extents are of uniform size.

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Sarkar

• Mar 29th, 2016

I want to know about wrap background logic.

akebono

 Profile Answers by akebono Questions by akebono

• Jan 30th, 2009

DBMS_OBFUSCATION_TOOLKIT package is  a simple API for data encryption

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