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Posted by Erland Sommarskog on 03/24/06 10:29
Chris Weston (chrisweston[losethislot]@ntlworld.com) writes:
> I should have been clearer over the conditions, but you made the correct
> assumption. That's useful advice, thank you very much. I can certainly
> add more indexing as you suggest, but is there any performance or
> resource overhead in having many indexes?
There is no such thing as free lunch, and an index comes with a cost yes.
The more indexes there are on a table, the longer inserts, updates and
deletes will take. It's difficult to quantify. Adding one more index, rarely
gives dramatic effect on these operations, but eventually there may be a
straw that breaks the camel's back. On the other hand, adding an index
can have drastic impact on a query, usually to the better.
--
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se
Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/prodtechnol/sql/2005/downloads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodinfo/previousversions/books.mspx
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