The Hidden Performance Costs Of Collation Mismatch

Nate Johnson explains why you want collation consistency when joining tables together on varchar/nvarchar columns:

There’s a subtle difference here, vs. those many community blog posts, which I’ll repeat.  The columns are of the same type.  Just different collations.

And when the collation on the join predicates is different, bad things happen. Let’s take CustomerNumber for example. On the ERP side, it’s a nvarchar(20) collate Latin1_General_100_CI_AS. On the internal & web apps side, it’s a varchar(20) collateSQL_Latin1_General_CP1_CI_AS. As you might imagine, this is a prime field for joining because it’s the main customer identified throughout all the systems.

Let’s be clear here. This is a numeric value only. Did it need to support Unicode? Absolutely not. Should it have been an int or bigint? Probably. But did The ERP designers choose to make it Unicode string anyway? Yep.

Read on to see how Nate tries to dig himself out of this hole.

Related Posts

Managing Central Management Server

Chrissy LeMaire shows how you can use dbatools to manage Central Management Server and registered servers: It’s a super useful feature that not all DBAs know about. Since CMS data is stored in msdb and accessible via SMO, you can access it from SQL Server Management Studio or PowerShell modules like dbatools. Central Management Server’s essential […]

Read More

Checking File Sizes In SQL Server

Andy Mallon looks back at a contribution by Junior DBA Andy, this one on checking file sizes: This is every DBA’s favorite game. Figuring out what DMV contains the data you want. It turns out there are two places that database file size info is maintained. Each database has sys.database_files which has information for that database. The […]

Read More

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Categories

July 2018
MTWTFSS
« Jun  
 1
2345678
9101112131415
16171819202122
23242526272829
3031