Comments on: All indexes are unique

By: Gail

Gail — Fri, 21 Jan 2011 21:18:50 +0000

There are many times that it’s a good thing to have a nonclustered primary key. Main one is when there’s a better place for the clustered index (eg because of access path or data type(s) of the primary key)

Unfortunately there is no simple, always applicable, straightforward answer here.

Just make sure that if the PK is nonclustered, there is a clustered index somewhere else.

By: Rich Yarger

Rich Yarger — Fri, 21 Jan 2011 18:44:00 +0000

Hello – have been recently reading your posts, and wanted to ask a very rookie-like question…When is it good to use a NonClustered Index on the Primary Key of a table, over a Clustered one? I am about to deploy a new setup, and went through to verify that the Primary Keys on all of my tables were in fact – Clustered. They weren’t, and when I asked why the only explanation I got was s shoulder shrug. These are programmers that put it together.

So needless to say – I changed them all to Clustered Index Primary Keys. Can you think of a reason or time when it would be a good thing to go with a NonClustered Primary Key?

Thanks and keep up the great work!

By: Gail

Gail — Fri, 18 Dec 2009 16:02:46 +0000

It’s in the 2005/2008 documentation as well, if one is willing to read through lots of different topics.

By: Victor

Victor — Fri, 18 Dec 2009 05:37:40 +0000

Hmmm…

This has been documented in SQL Server 7.0 courseware.

By: Henrico

Henrico — Tue, 10 Nov 2009 12:59:41 +0000

just came across this post, really opened my eyes to indexes (know it sounds very dramatic)

By: SQL Server Uniqueifier Values and the Number of the Beast

SQL Server Uniqueifier Values and the Number of the Beast — Fri, 13 Feb 2009 19:43:56 +0000

[...] Gail Shaw’s post All indexes are unique, reminded me of an interesting piece of trivia I discovered back in SQL Server 7. The error message [...]

By: Now syndicating Gail Shaw and Kendal Van Dyke | Brent Ozar - SQL Server DBA

Now syndicating Gail Shaw and Kendal Van Dyke | Brent Ozar - SQL Server DBA — Tue, 10 Feb 2009 23:10:57 +0000

[...] All Indexes Are Unique – no, really.

By: Gail

Gail — Tue, 10 Feb 2009 16:37:42 +0000

The main intention was to make people think about index structure. So many questions on indexing are simple if the structure if the index is understood.

By: Grant Fritchey

Grant Fritchey — Tue, 10 Feb 2009 14:00:11 +0000

That’s a really weird way to think about it, but you know what, it’s utterly true. Well done.