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Composite indexes
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Forum:
Oracle
Catégorie:
Autre
Divers
Thread ID:
00464754
Message ID:
00466487
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8
You mean disk partitions right? Well you can like any index as far as I know it just depends on the physical location of the index segement/ tablespace which you can control when you create it.

If you are using raid 0 or 1 this migth be a good thing. If you are just using
single disks this would definately be a bad thing in terms disk i/o necessary to
that being said a bitmap index is small in size and can usually be stored in the db buffer (if used frequently or you can pin it.) In this case the whole index will be read from memory and it won't matter where or how many logical disks the index is stored on.



>< snip >
>>But seperate a key concept(s) in indexes are
>>- to keep them as compact as possible (less rows need to be scanned off disk and less memory needs to be used.)
>>- if the index does not have many different values i.e. only 0 or 1 use a
>bitmap index.
>
>another question -- in 8i can you use bitmap indexes across partitions?
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