I just read in a forum about a user who want to replikate a table, but the table doesn't have a PK. The table is pretty large, and having the table not available while adding the PK is undesireable. The table has a clustered index already, and there are...(read more)

Welcome to October! This week I have five SQL Server items to point out to you, and two Connect-specific issues. /*------------------------------------------------------*/ SQL Server /*------------------------------------------------------*/ #331220 :...(read more)

Time flies when you're having fun, eh? This week Paul and I are in Dublin, Ireland delivering a deep technical "SQL Immersion Event" on Internals, Performance Tuning and Maintenance with our partner ProData (and having a blast - we have a really fun and very interactive group). And, today's an even more interesting ...

Let's start with some background on forwarding pointers: Forwarding pointers in heaps can be a mess to get rid of. A forwarding pointer happens when you modify a row so that the row doesn't fit on the same page anymore. SQL Server moves the row to a new...(read more)

The old sysindexes table (as of 2005 implemented as a compatibility view) has a useful column named keycnt. This is supposed to give us the number of columns (keys) in the index. However, to make heads and tails out of the numbers, we need to understand...(read more)

This is a recommendation I believe is worth repeating from time to time: Make sure you match data types when you write TSQL code. Else you in most cases end up with an implicit data type conversion. And in worst case, this conversion is performed at the column side - not the literal side of your query. What does that mean? Consider below: WHERE ...

Recently, the SQL Server 2008 Internals title was released (and only in the past few days have people actually received their copies! In fact, I still haven't seen the book in person... soon though!) Anyway, Kalen, Paul, Conor, Adam and I worked to create a comprehensive resource on SQL Server 2008 internals and to supplement ...

I started the series here: http://www.sqlskills.com/BLOGS/KIMBERLY/post/Spring-cleaning-your-indexes-Part-I.aspx and I want to continue with Part II today by clarifying some great questions/comments that have come up on the series. In Part III, I'll give you a few more ways to get rid of (or consolidate) indexes. And, I think ...

First and foremost, happy spring! I truly hope we're on the path to summer (although who would know it here - we're in Florida for SQL Connections and the weather is a bit chilly and it's been raining off/on today - I hope this is short term (no, I don't want to look at the forecast as I don't want to jinx it :)). But, ...

When you decide to rebuild or reorganzie an index, you have an option to set something called FILLFACTOR. This is probably the MOST IMPORTANT thing to understand about index maintenance and reducing fragmentation (especially in databases that are prone to it). Unfortunately, we need to dive into some internals to really understand why this is so ...