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That is a cluster index
i.e. an index on a cluster, rather than on a table.
It is not a clustered index as in Microsoft SQL server
Which is in concept closer to an IOT but is implemented via create index.
There is no such clustered index in Oracle.
Nag Aswadhati wrote:So to your original answer
There is clustered index in sql server.
In oracle there is Index Organized Table
Nag Aswadhati wrote:You mean to say having a primary key forces a table to become an IOT?
Yes there is the difference between a PK and Unique + Not null.
PK -- Clustered Index
Unique --> Non Clustered Index
I think everyone who wrongly thinks Oracle has clustered indexes needs to read this before spreading any more misinformation.
Finally, when you want to enforce co‐location of data or you want data to be physically
stored in a specific order, the IOT is the structure for you.
For users of Sybase and SQL Server, this is when you would have used a clustered index,
Nag Aswadhati wrote:No it does not. There is a little similiarity between both. However indexes are constructs mainly used for performance reasons (unique indexes are an exception to that rule). In this regard oracle, sybase and all otehr databases differ greatly. Concepts used on the one database can not be used in similiar way on the other. The reasons why sybase has clustered indexes do not exist in oracle.
I dont mean that....
Having a primary key table not becomes an IOT?
an IOT might behaves like clustered index in sql server.
See also: http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::p11_question_id:586423377841