Is it a bad idea to use GUIDs as primary keys in MS SQL?

Question

We have a system that uses UniqueIdentifier as the primary key of each of the tables. It has been brought to our attention that this is a bad idea. I have seen similar post

Answer 1

I wrote a post about this last week with some code to show you what happens: Some Simple Code To Show The Difference Between Newid And Newsequentialid

Basically if you use newid() instead of Newsequentialid() you get horrible page splits if your PK is a clustered index (which it will be by default)

Answer 2

There are pros and cons:

This article covers everything.

GUID Pros

• Unique across every table, every database, every server
• Allows easy merging of records from different databases
• Allows easy distribution of databases across multiple servers
• You can generate IDs anywhere, instead of having to roundtrip to the database
• Most replication scenarios require GUID columns anyway

GUID Cons

• It is a whopping 4 times larger than the traditional 4-byte index value; this can have serious performance and storage implications if you're not careful
• Cumbersome to debug (where userid='{BAE7DF4-DDF-3RG-5TY3E3RF456AS10}')
• The generated GUIDs should be partially sequential for best performance (eg, newsequentialid() on SQL 2005) and to enable use of clustered indexes