We had a customer issue today that ended up being by-design but was confusing enough that I offered to write up a blog post so that people could reference it in the future.  It boils down to the question “when should ROW_NUMBER() be computed in a...

For those interested, I will be speaking at the SqlBits conference in London, UK at the end of March.  I’ll be giving the Saturday keynote (on the new Batch processing engine in SQL 2012 used with Column Store indexes) and 2 other talks (one on Data...

For those of you watching SQL Azure, you probably have noticed that it releases more frequently than regular SQL Server.  There was a release in late November/early December (it is complicated since the installation of the new software is done largely...

  I haven’t posted much on the new SQL Server 2012 features yet, but I’m going to start doing so soon.  I’ll also be speaking about them at upcoming conferences.  We have an exciting new index type in SQL Server 2012 that is column-oriented...

(I promised I’d write more ) Today I will talk a bit about Distributed Query (DQ), a feature that lets you query across databases/servers.  I’ve previously posted an academic paper we wrote on the subject some time back ( http://citeseerx.ist.psu...

I’m not one for New Year’s Resolutions, but I am going to try to blog a bit more.  It’s hard to describe working at Microsoft, especially as one gets more senior.  There are lots of really smart people.  There’s an ability to work on problems...

I have been playing with the XEvent feature in SQL 2012 (RC0) and there are a few gotchas that I hit.  I figured I’d post them up here so that others could learn from my experiences.  I was trying to do something pretty simple – get the % Processor...

I had a great time visiting Belgrade last week.  I’d like to thank everyone who attended one of my talks and I wanted to post up the slide decks for those who would like to see them.  One talk was on the new SQL 2012 ColumnStore index feature...

As a professional announcement, I will not be speaking at PASS this year (nor will I be at the conference).  Instead, I will be in Belgrade, Serbia the following week to speak at the Sinergija 11 conference.  I’ll be doing a talk on the new...

  Question (paraphrased):  “Conor, does changing the max server memory settings always empty the plan cache on SQL 2005 and 2008?” Answer: yes, this is what happens and what is supposed to happen.  One of the inputs to the optimizer is...

I'll be talking about one of the new things our team has been develping this Saturday at the SQL Saturday event in Austin ( http://www.sqlsaturday.com/97/eventhome.aspx) on the new ColumnStore index being added in the upcoming release of SQL Server. It...

I’ve received a question about parallel execution plans from a customer. ( http://technet.microsoft.com/en-gb/library/cc966425.aspx ) Execution contexts for parallel plans are not cached. A necessary condition for SQL Server to compile a parallel query...

Here is the slide deck from my presentation at SQLBits Friday in Brighton file   I had a great time at SQLBits, even though I had to leave early.  Thank you to everyone who attended the talk and to those who asked questions and gave me feedback...

I will be in Brighton, England this upcoming Friday where I will be speaking at the SQLBits conference.  I plan to give a talk that goes deep into how many SQL Server processes Update queries (Insert, Update, Delete).  So, if you’ve ever wanted...

I found this paper interesting, so you might too.  It covers some of the differences between parallel database systems and map-reduce style computation: http://database.cs.brown.edu/papers/stonebraker-cacm2010.pdf Happy Querying! Conor

I received an email from a reader this weekend that has a lot of different questions, but one of the main questions related to the difference between views and base tables in SQL Server’s plan generation process.  ie if I have a view “select * from...

I thought I’d do a small post about some of the reasons I got into computers since I’ve randomly had a few opportunities to revisit them.  Tron 2 came out recently, reminding me of the original movie.  Additionally, I went home for the holidays...

I got another question in the mail this week from another reader:   Hi Conor Thanks for an interesting blog. Maybe you have the answer to this question: Why I SQL Server having performance problems with these types of expressions: --------------...

I received a question this week from a reader about how SQL Server determines the join order if there are more than 6 joins in a query. There are a lot of details about how SQL Server’s optimizer works here, and some of them are beyond the level of detail...

At PASS last week, I was asked about fragmentation caused by RCSI when a row is first converted to use RCSI. I talked to some people in the team and found that one of my colleagues had already written a nice blog entry about it. http://blogs.msdn.com...

I had a great time at PASS last week and got to talk to a lot of wonderful customers- thank you! As promised, here are the decks: Update Talk Performance Troubleshooting Talk Happy Querying! Conor

It’s one of the most exciting weeks of the year to be a SQL Server junkie – PASS is this week in Seattle! I’m giving a talk on the many details of Update queries.  It will cover the various operators and how they work, why the plan shapes look the...

A note to let you know that I will be at PASS this year and plan to give two talks (one in collaboration with a colleague of mine on the QP). One will be a 500 level talk on how Update queries work – lots and lots of gory details.  The other will...

A question from a reader (thank you, Price, for sending it in).  This is a follow up to my prior post on Optional parameters http://blogs.msdn.com/b/conor_cunningham_msft/archive/2010/04/22/conor-vs-optional-parameters.aspx . The question is whether...

I am giving a talk tomorrow (Tuesday) night at the Austin PASS group on how Update Queries are processed/optimized in SQL Server.  The talk will be at the Microsoft office in Austin (which recently moved). More details can be found at the CACTUS...