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Great article. One disadvantage to a clustered index that I hear a lot of people claim is disk space. How much disk space does a clustered index actually take up compared to the table it is indexing?

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Jgoodwin,

from Chris Hedgate's response we should notice that the extra space needed for the clustered index is highly dependent on the key size. For the table with 10000 data pages, if the key size was 5, only 16 pages (0.2%) were needed; but if the key size were 1000, it would take about 1430 pages for the index (that's 15% more space): 8096/1007=8, 10000/8 + 10000/8/8 + 10000/8/8/8 + ... + 1 = 1430. And this is only for the clustered index itself, but the other non-clustered indexes will need extra space too.

Conclusion: you SHOULD use a clustered index, but the key for the index must be small (less than 100 bytes, ideally 4 or 8 bytes).

Razvan