SQL Server GUID Column with Index Considerations and Identifcation Scripts
Problem On some of the SQL Server databases I manage, I noticed that there are tables with GUID columns and the GUID column is defined as the primary key. On checking further, I noticed that these GUID columns also have a unique clustered index on the column . What are the issues with this approach especially when the database grows considerably?
I have been looking for areas to add foreign keys, and in turn index those columns to improve the performance of joins. However, many of our tables are joined on an id that is a GUID type, generated upon insertion of an item, and the data associated with that item in other tables is generally has column item_id containing the GUID .
Should I get rid of clustered indexes on Guid columns
By default SQL Server places a clustered index on primary key columns . I understand that this is a silly idea for GUID columns , and that non-clustered indexes are better. What do you think - should I get rid of all the clustered indexes and replace them with non-clustered indexes? Why wouldn't SQL's performance tuner offer this as a recommendation?
Lookups on the GUID are going to be fast all the rows are cached in memory. Using a nonclustered index on the GUID won't really help if you need all the other columns , and introduces an extra layer of indirection. Also you can look at generating sequential GUIDs on the client with either UUIDCreateSequential + byte shuffling, or other techniques.
sql server
I would create a Unique Non Clustered index on the GUID column which was the primary key. The smaller remote 150 databases don't need to know about the new PK on the central SQL Server database - its purely going to be used for organising the data in the database and stop the bad performance and fragmentation.
Problem Please provide T-SQL examples that illustrate how to create and use GUID values in SQL Server . Also, show how to analyze GUID values with T-SQL. Include a couple of examples on how to detect duplicate values in a column of GUIDs . Additionally, discuss how duplicate values can exist in columns of globally unique values.
Best Practices for Using GUID as Primary Key
Abstract: This article provides an in-depth analysis of performance considerations and best practices when using GUID as primary key in SQL Server . By distinguishing between logical primary keys and physical clustering keys, it proposes an optimized approach using GUID as non-clustered primary key and INT IDENTITY as clustering key. Combining Entity Framework application scenarios, it ...
All column constraints and properties, except IDENTITY, can be used on the uniqueidentifier data type. Merge replication and transactional replication with updating subscriptions use uniqueidentifier columns to guarantee that rows are uniquely identified across multiple copies of the table.
Double the Performance of Your App When Using GUIDUUID ...
A walkthrough of performance considerations when using GUID /UUIDs for database Primary Keys, including code optimizations and benchmarks.
