An Extent is a specific number of contiguous data blocks, obtained in a single allocation, and used to store a specific type of information.

gaurav_varma

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• Jan 10th, 2007

An extent is a logical unit of database storage space allocation made up of a number of contiguous data blocks. One or more extents in turn make up a segment. When the existing space in a segment is c...

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A segment is a set of extents allocated for a certain logical structure.

gaurav_varma

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• Jan 10th, 2007

A segment is a set of extents that contains all the data for a specific logical storage structure within a tablespace. For example, for each table, Oracle allocates one or more extents to form that ta...

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Data Segment, Index Segment, Rollback Segment and Temporary Segment.

taraldesai

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• Jan 28th, 2008

Data, index , rollback, undo,cluster

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Each Index has an Index segment that stores all of its data.

taraldesai

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• Jan 28th, 2008

It's an oracle object as other object like table. It stores index key + rowid for that key. So when you scan index it finds respective rowid and fetch data from that rowid. and it's faster

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A Database contains one or more Rollback Segments to temporarily store "undo" information.

taraldesai

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• Jan 28th, 2008

It stores your uncommited temporart data. ex. If you do any insert/update/delete and you won't commit it is written in rollback segment.

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Here i'm sending all of you the error which occurred frequently during database connection.While creating a data block in Oracle Forms, the error which encountered frequently is "ORA-12560: TNS Protocol Adapter Error" During lectures instructor had told us that if such error encountered then copy the TNSNAMES.ORA file from ..oracleora92networkadminsample to forms9inetworkadminsample as it contains...

sahil4439

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• Jun 15th, 2008

dude  ur databse is not running...right click on my compiuter>manage>services& applictaions(on right side)>services>oracle_databse_name(the datasbe  that ur  trying ...

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what is remote login user and local user in database?And sid is used when user want to login as local user and Glodal database name is used when user wants to login as remote user..What does it mean ?

cmanan

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• Jul 10th, 2008

When you have distributed environment,you may access one database from other.This is normally done  via db link.So lets say you have flight database and customer dabatabase.Now from customer data...

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Hi,

If a user executes a query which is already being used by a view exactly will oracle use already existing view to retrieve data or use the query executed by user?

Regards,
Shashi

Aayudh

• Aug 24th, 2011

Oracle uses query executed by user because when you use a view name in an other query, it simply transform query. select empid,name from emp; --- original create view emp_view as select empid,name f...

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If a foreign key reference a parent key of the same table is called self-referential integrity constraint.

samiksc

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• Jan 19th, 2006

Self referential integrity constraint refers to two columns related by referential integrity which belong to the same table.For example ManagerId column in employees table is a foreign key which refers to EmployeeId in the same table.

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The condition must be a Boolean expression evaluated using the values in the row being inserted or updated and can't contain sub queries, sequence, the SYSDATE,UID,USER or USERENV SQL functions, or the pseudo columns LEVEL or ROWNUM.

fancyoracle

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• Aug 16th, 2007

A check constraint allows you to specify a condition on each row in a table. Note: A check constraint can NOT be defined on a VIEW. The check constraint defined on a table must refer to only columns i...

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A synonym is an alias for a table, view, sequence or program unit.

thumatinagaraju

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• Oct 24th, 2006

Ya synonym is used to rename or to create alias for the data base object ..

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Clusters are groups of one or more tables physically stores together to share common columns and are often used together.

partho sarathi konar

• Oct 1st, 2006

Clusters are groups of one or more tables physically stored together because they share common columns and are often used together. This improves disk access time.The related columns of the tables in ...

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A row is stored in a hash cluster based on the result of applying a hash function to the row's cluster key value. All rows with the same hash key value are stores together on disk.

partho sarathi konar

• Oct 1st, 2006

Hash Clusters cluster table data in a manner similar to normal, index clusters. To find or store a row in a hash cluster, Oracle applies a hash function to the row's cluster key value. The resulting h...

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In Circumstances, all of the data for a row in a table may not be able to fit in the same data block. When this occurs , the data for the row is stored in a chain of data block (one or more) reserved for that segment.

feroz

• Aug 29th, 2006

If a row is too large to fit into a single database block row chaining happens. For example, if you use a 4KB blocksize for your database, and you need to insert a row of 8KB into it, Oracle will...

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