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    <p>You don't mention which sql server you are using</p> <p>If you are using MySql there are definite advantages in speed to using fixed length fields to keep the table in static mode, however if you have any variable width fields the table will switch to dynamic and you lose the benefit of specifying the length of the field.</p> <p><a href="http://dev.mysql.com/doc/refman/5.0/en/static-format.html" rel="nofollow noreferrer"><a href="http://dev.mysql.com/doc/refman/5.0/en/static-format.html" rel="nofollow noreferrer">http://dev.mysql.com/doc/refman/5.0/en/static-format.html</a></a><br/> <a href="http://dev.mysql.com/doc/refman/5.0/en/dynamic-format.html" rel="nofollow noreferrer"><a href="http://dev.mysql.com/doc/refman/5.0/en/dynamic-format.html" rel="nofollow noreferrer">http://dev.mysql.com/doc/refman/5.0/en/dynamic-format.html</a></a></p> <p><p>Microsoft SQL Server has similar performance gains when you use fixed length columns. With fixed length columns the server knows exactly what the offset and length of the data in the row is. With variable length columns the server knows the offset but has to store the actual length of the data as a preceding 2byte counter. This has a couple of implications that are discussed in this <a href="http://www.databasejournal.com/features/mssql/article.php/3718066/Disk-Space-Usage-and-SQL-Server-Performance.htm" rel="nofollow noreferrer">interesting article</a> that discusses performance as a function of disk space and the advantages of variable length columns.</p> <p>If you are using SQL Server 2005 or newer you can take advantage of varchar(max). This column type has the same 2GB storage capacity of BLOBs but the data is stored in 8K chunks with the table data pages instead of in a separate store. So you get the large size advantage, only use 8K in your pages at a time, quick access for the DB engine, and the same query semantics that work with other column types work with varchar(max).</p> <p>In the end specifying a max length on a variable column mainly lets you constrain the growth size of your database. Once you use variable length columns you lose the advantage of fixed size rows and varchar(max) will perform the same as varchar(10) when holding the same amount of data.</p>
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    1. POHow much more inefficient are text (blobs) than varchar/nvarchar's?
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