Index Statistics

TSQL
The other day a developer showed up at my desk. They were getting time-outs in production on a query that didn't normally give them trouble. With the parameters they provided, I ran the query. It ran for over 30 seconds, the application side timeout, before it returned it's data. So I ran it again with an execution plan. It had a bunch of index scans with loop joins across thousands of rows and even created a table spool with 700 million rows as part of the process. Clearly not good. Next I looked at the query plan. It wasn't too bad, as these things go. It was probably moving too many columns and apparently the business wanted a pivot on the data since they were using an aggregate method to pivot some…
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Top Vs Max

SQL Server 2005, SQL Server 2008, TSQL
I finished a set of research and tests. I put it all together and gave it to Chuck Heintzleman at SQL Server Standard (that web site can use some help). Hopefully he likes it and publishes it. I understand that the upcoming issue will be on performance tuning. If he doesn't like it, I'll get it over to Peter Ward at SQL Server Performance or to Steve Jones at SQL Server Central. I'm posting this because I see so many web searches looking for information comparing TOP to MAX. Here are some short answers for those interested. Data to support these suggestions is included with the article. ROW_NUMBER works best with smaller data sets. TOP has more consistent operation over a range a data. MAX frequently resolves as a TOP operation, but sometimes…
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Top vs. Max

TSQL
The company I work for has a very well defined need for versioned data. In a lot of instances, we don't do updates, we do inserts. That means that you have to have mechanisms for storing the data that enables you to pull out the latest version of all the data or a particular version of all the data, or the data at a particular moment in time, regardless of version.  That means maintaining a version table and a series of inserts into various tables. Some tables will have pretty much a new row for each version, some tables may only have one or two versions out of a chain. With the help of a very smart Microsoft consultant, Bill Sulcius, we have a mechanism that works very well. However,…
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