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Overview of clustered and nonclustered index - not DB specific (as I understand):

Clustered Index: The physical order of data. As a result, a table can only have one clustered index.

Nonclustered Index: One or more nonclustered indexes can be configured per table. Does not directly impact the organization of the data page.

Is there a difference between how Microsoft SQL Server and Oracle 'manage' clustered and nonclustered indexes? Or is it the same across the DBS?

Any guidance would be great!

user2112730
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1 Answers1

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Oracle does not have a concept of a clustered index. So your premise that the question can be database agnostic is flawed. Oracle also does not have the concept of a "page" like SQL Server does.

For situations where the physical order of data in a table is truly important, Oracle allows you to define a table as an index-organized table or a single-table hash cluster. But the implementation is completely different from that of a clustered index. An index-organized table, for example, will store the table's data in the index so there is no table segment (unless you define an overflow segment).

Justin Cave
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    I think there is no real difference between a clustered index in SQL Server and an index organized table in Oracle (apart from the name). –  Nov 08 '14 at 16:01
  • In case of an IOT the implementation does not seem different at all. Both engines use a B-tree and no heap. – usr Nov 08 '14 at 16:30