Big clustered index rebuild

I need to establish the storage requirements for a clustered index rebuild with SQL 05. The table is made up of the following columns

[ProductID] [int] NOT NULL,

[RegionID] [int] NOT NULL,

[TimeID] [int] NOT NULL,

[FactID] [int] NOT NULL,

[Value] [decimal](14, 4) NOT NULL

This is the clustered index :-

[RegionId] ASC,

[FactId] ASC,

[TimeId] ASC,

[ProductId] ASC

This is the result of a sp_spaceused on this particular table

name rows reserved data index_size unused Table 16910379278 868107368 KB 863579184 KB 3869848 KB 658336 KB

The database where this table is stored is in Simple recovery mode.

What i would really like to know is, what additional storage would i require to run the following rebuild index command.

Alter Index blah on table Rebuild

Thanks

There is a nice explanation here.

WesleyB

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