Conor vs. SQL : SQL

Conor vs. UNIQUE in Index Definitions

Conor Cunningham [MSFT] — Wed, 21 Oct 2009 16:18:50 GMT

I gave a talk to the Austin-area PASS group last night on B-Tree indexing in SQL Server, and I received a question about whether to make clustered indexes UNIQUE or not (assuming the data is unique on the key columns). The expectation was that this...(read more)

Conor vs. Isolation Level Upgrade on UPDATE/DELETE Cascading RI

Conor Cunningham [MSFT] — Fri, 13 Mar 2009 18:12:52 GMT

A customer recently asked our support organization about an unexplained series of range locks that they were seeing on a DELETE to a table with a foreign key. Here is the repro: 1: create table Foo (FooId int not null primary key ) 2: create table...(read more)

Conor vs. Non-ANSI NULLs, part 1

Conor Cunningham [MSFT] — Mon, 09 Feb 2009 07:45:00 GMT

I was thinking about indexed views. Well, more specifically, I was thinking about why indexed views are hard to use. One of the reasons that they are hard is that there are just so many restrictions. Anyways, one of the things I'd like to better understand...(read more)

Conor vs. MERGE and PRIMARY KEY collisions

Conor Cunningham [MSFT] — Thu, 05 Feb 2009 05:51:30 GMT

MERGE is a new operation added in SQL Server 2008. It has all sorts of knobs, bells, and whistles. The primary value of this feature is to collapse multiple query statements into one query statement. Overall, this avoids the “overhead” necessary to run...(read more)

OPTIMIZE FOR UNKNOWN - How could that possibly make any sense???

Conor Cunningham [MSFT] — Fri, 16 Jan 2009 18:32:00 GMT

Yes, I'm alive. I have been chatting with my wife about the times I need to "go dark" - in this case, I am working on features that I can't discuss yet, other than to say that I am *very* excited to go to work every day.. (well, since I work out of my...(read more)

The vote is in! (CHECK CONSTRAINTS vs. TRIGGERS vs. STORED PROCEDURE business logic)

Conor Cunningham [MSFT] — Tue, 04 Nov 2008 02:50:00 GMT

Thank you for everyone who "voted" - a great day to talk about the issues of the day :). After much research, I've found that we live in a divided country. Some of us like triggers. Others wouldn't be caught dead with a trigger and do lots of business...(read more)

More Business Logic Validation

Conor Cunningham [MSFT] — Fri, 31 Oct 2008 22:15:00 GMT

I've gotten a few data points, but I don't think I've had enough yet to complete my sample. I'm still looking for people willing to describe how and where they implement business logic in their database applications. 1. CHECK CONSTRAINTS 2. TRIGGERS 3....(read more)

CHECK Constraints vs. TRIGGERS

Conor Cunningham [MSFT] — Tue, 28 Oct 2008 18:50:00 GMT

I've been having a conversation with a customer about CHECK constraints and TRIGGERs, and I thought it would be good to survey some of our customers about how people use these features. I'm curious how many people encode business logic validation in CHECK...(read more)

CONVERT vs. CONVERT_IMPLICIT

Conor Cunningham [MSFT] — Fri, 24 Oct 2008 17:19:00 GMT

Today's question comes from a friend I have in Brazil. Please, tell-me one thing, is there any improvement in avoid Implicit Conversions forcing one explicit conversion? Or will QP behind the scenes execute the same SQL using the function CONVERT()? These...(read more)

Foreign Keys are our friends...

Conor Cunningham [MSFT] — Thu, 07 Aug 2008 20:46:00 GMT

I often find customers who question the value of database-enforced integrity constraints. While people often create primary keys, the foreign ones are perhaps a bit more .... well, foreign. Let's start at the beginning. In traditional, old-school database...(read more)