Comments on: SQL Server Index Tuning Tip: Identify Overlaps

By: The Plague of Plagiarism | The SQL UPDATE Statement

The Plague of Plagiarism | The SQL UPDATE Statement — Fri, 15 Jan 2010 02:24:32 +0000

[...] it? Well guess what? They’re not my words, they’re Brent Ozar’s words from his article on SQL Server Index Tuning Tip: Identify Overlaps. Now had I mentioned that fact, would you know I didn’t write it? Well that is the meat of a hot [...]

By: Fer

Fer — Wed, 07 Oct 2009 07:01:01 +0000

Thanks Brent!

By: Brent Ozar

Brent Ozar — Tue, 06 Oct 2009 17:57:46 +0000

Ah, great question. The order does indeed matter. It’s too big of a subject matter to cover here, but I highly recommend picking up Grant Fritchey’s book SQL Server 2008 Query Performance Tuning Distilled. I wrote a review of it here:

http://www.brentozar.com/archive/2009/04/book-review-sql-server-2008-query-performance-tuning-distilled/

The short story is that no, the order of the fields in the joins and the wheres isn’t going to matter as much as some other things you can do to improve query tuning performance.

By: Fer

Fer — Tue, 06 Oct 2009 17:41:48 +0000

Yes, sorry.

After run the db engine tunning advisor, it proposes to me 6 or 7 index to create in one table, but the fields are the same in 4 or 3 of them in diferent order.

I’m a developer and the tunning is new for me. My questions is: if i modify my querys, changing the order of the fields in the “joins” and “wheres” could i minimize the number of indexes?

Thanks in advance

By: Brent Ozar

Brent Ozar — Tue, 06 Oct 2009 17:28:09 +0000

I’m not sure what you mean – can you elaborate?

By: Fer

Fer — Tue, 06 Oct 2009 16:42:33 +0000

Hi! If the indexes contain the same fields but in different order, ¿Is posible to drop any if i change the order of the fields in my selects?

Thanks

By: SteveO

SteveO — Mon, 06 Jul 2009 18:39:57 +0000

That van needs a Decepticon logo on the gril. ;->

Saw transformers over the weekend it it just needs it.