Re: Meaning of Reverse index ?

> If the index start from 1-10000, then the reverse key will still be
1-10000

Don't think about it that way... Think of it as: "Reverse-key indices have the keys more evenly distributed," which is what Jim was trying to get at.

In other words, it is bad for an index of this type to have many values bunched together. If you have contiguous values from 1000 to 1500, then it is not as good for an index as if you had values 0001 to 9941 (the reversed values). This is because the whole mechanism works better if you have a wide range of values. When you insert #1300 the key will be 0031, when you insert the next element #1301 the key will be 1031, very far apart from 0031. Otherwise, you'd be entering key 1300 then immediately 1301, which would probably cause bucket contention...

Have you studied about buckets b-trees, etc...? If you have, then you'll understand why reverse keys are so helpful. Received on Tue Mar 04 2003 - 08:30:46 CST