Max width for indexed column?

Is column width a factor for an indexed column? Would indexing a
VARCHAR(100) be a bad idea? Any links to discussion of this topic?
Thanks for your advice.
- Joe Geretz -'bad' is of course a relative term...
Yes, width of an index will affect performance. This is a LONG topic, but
here a a few thoughts...
* width of a clustered index can be more important to worry about than a NC
index since a clustered index key is propogated through ALL the NC indexex.
* yes, width does matter. Intuitively, it just makes sense. There is less
CPU and much less IO involved for a 10 byte index than a 100 byte index.
Would it be quicker for you to read a list of 10 letter words or 100 letter
sentences? Of course that's a silly example, but yes... narrow indexes will
be better all things considered.
* having a wide index isn't the end of hte world and probably isn't a big
deal with smaller data sets.
* if you DO need to index wide char based fields and you are worred about
performance... you may want to consider creating a checksum based on the
chat column and indexing the checsum col (which will be an integer). That
would be much faster...
--
Brian Moran
Principal Mentor
Solid Quality Learning
SQL Server MVP
http://www.solidqualitylearning.com
"Joseph Geretz" <jgeretz@.nospam.com> wrote in message
news:e7LEw0RiEHA.344@.TK2MSFTNGP10.phx.gbl...
> Is column width a factor for an indexed column? Would indexing a
> VARCHAR(100) be a bad idea? Any links to discussion of this topic?
> Thanks for your advice.
> - Joe Geretz -
>