Posted by John Bokma on 03/07/06 20:56

John Bokma <john@castleamber.com> wrote:

> I have a table containing URLs. I want to be able to look up an URL
> very fast, so I used an nvarchar to store the URL, and put an index on
> it (maybe naive).
>
> Anyway, I bump into:
> "The index entry of length 911 bytes for the index 'UQ__URL__1367E606'
> exceeds the maximum length of 900 bytes."
>
> What's the best way to handle this? I want to do the look up fast. The
> only thing I could think up was adding an extra column containing a
> digest for the URL, and look up all URLs with the same digest, *and*
> having the same value (which could give either 1 or 0 results).
>
> I am new to MS SQL, so I might describe a silly solution, basically I
> want to look up URLs to ID the fastest way possible.

To answer my own question: under CHECKSUM in SQL Server Books Online:

"The checksum index can be used as a hash index, particularly to improve
indexing speed when the column to be indexed is a long character column."

Comes with an example, etc.

--
John MexIT: http://johnbokma.com/mexit/
personal page: http://johnbokma.com/
Experienced programmer available: http://castleamber.com/
Happy Customers: http://castleamber.com/testimonials.html

[Back to original message]