Version 1.0 is Now Available! I’ve been working off and on, as my real job permits, on this visualization tool for SQL Server data files. This is an educational or exploratory tool where you can more readily see how the individual data pages in MDF/NDF files are organized, where your tables and indexes live, what effect operations like index ...

This is part three of a blog series illustrating a method to render the file structure of a SQL Server database into a graphic visualization. Previous Installments: Part 1 Part 2 Those that have been reading this series might be be thinking, “Is he going to go there?” Well, the answer is “Yes.” This is the GUID clustered index post that had to ...

Part 2 of a blog series visually demonstrating the layout of objects on data pages in SQL Server Part 1 In Part 1 of this series, I introduced a little demo app that renders the layout of pages in SQL Server files by object. Today I’ll put that app through its paces to show, in vivid color (well, teal, anyway) the destructive power of the famous ...

Part 1 of a blog series visually demonstrating the layout of objects on data pages in SQL Server Some years ago a gentleman called Danny Gould created a free tool called Internals Viewer for SQL Server. I’m a visual sort of guy, and I always thought it would be fun and educational to make a simple visualizer, like the one he created, in order to ...

I thought I had said almost all that could be said about nonclustered index keys in a post made almost exactly two years ago, on March 16, 2008.  But there's more. To get all the benefit from today's post, you'll really have to read that one, but I'll synthesize the crucial details here. Every index needs to be unique, in some way or ...

Today, a reader asked me the following: ''How can I find the amount of space occupied by a worktable?. Using SET STATISTICS IO ON, I can only see the number of reads using the worktable, not the amount of space taken.'' What is a worktable? I always like to think of it as a temp table that SQL Server builds without being asked. While ...

Everytime a good product comes out, people seem to contrive bad ideas for what can be replaced, usually brains, or people with brains, or that people lacking brains can accomplish something on their own. Let me put it simply. Suppose one had a query that uses a nonclustered index, and required a key lookup, and the key lookup required a disk ...

An observant person has probably noticed that SQL queries requiring disk reads not only have longer duration but also higher CPU times. It is not hard then to deduce that disk access (for both HDD and SSD), which involves the OS performing an IO call, the SQL Server process finding a place in the buffer cache for the data pages, and possibly ...

I recently received a question about the storage of nonclustered index keys. I am assuming you are aware of the fact that if your table has a clustered index, SQL Server uses the clustered index key (all of its columns, if it is a composite index) as a 'bookmark' in your nonclustered indexes,  to allow your nonclustered indexes to uniquely ...

SQL Server 2005 allows rows to include variable length columns which do not actually fit in the maximum row size of 8060 bytes. I previously posted about row-overflow columns, and discussed the maximum number of such columns that you could have in a single table. You can read that post here. Just recently I received another question that ...