Question

I use several referenced tables with integer primary keys. Now I want to change ints to GUIDs leaving all references intact. What is the easiest way to do it?

Thank you!

Addition

I do understand the process in general, so I need more detailed advices, for example, how to fill new GUID column. Using default value newid() is correct, but what for already existing rows?

Answer 1

• Create a new column for the guid value in the master table. Use the uniqueidentifier data type, make it not null with a newid() default so all existing rows will be populated.
• Create new uniqueidentifier columns in the child tables.
• Run update statements to build the guild relationships using the exisitng int relationships to reference the entities.
• Drop the original int columns.

In addition, leave some space in your data/index pages (specify fillfactor < 100) as guids are not sequential like int identity columns are. This means inserts can be anywhere in the data range and will cause page splits if your pages are 100% full.