SQL Plan Archives - Page 12 of 12

Beware misleading data from SET STATISTICS IO

My co-worker Steve Wright (blog | @SQL_Steve) prodded me with a question recently on a strange result he was seeing. In order to test some functionality in our latest tool, SQL Sentry Plan Explorer PRO, he had manufactured a wide and large table, and was running a variety of queries against it. In one case he was returning a lot of data, but STATISTICS IO was showing that very few reads were taking place.

Aaron Bertrand ◆ October 30, 2012

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What is the fastest way to calculate the median?

Medians require sorting. Sorting in SQL Server is typically a pretty expensive operation if there isn't a supporting index, and adding an index to support an operation which probably isn't requested that often may not be worthwhile. This post explores the performance characteristics of several solutions to the median problem.

Aaron Bertrand ◆ August 29, 2012

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Conditional Order By

A common scenario in many client-server applications is allowing the end user to dictate the sort order of results. Some people want to see the lowest priced items first, some want to see the newest items first, and some want to see them alphabetically. This is a complex thing to achieve in Transact-SQL because you can't just throw @SortColumn and @SortDirection into a straight T-SQL query.

Aaron Bertrand ◆ August 8, 2012

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When the DRY principle doesn't apply : BITWISE operations in SQL Server

The "Don't Repeat Yourself" principle suggests that you should reduce repetition. This week I came across a case where DRY should be thrown out the window. There are other cases as well (for example, scalar functions), but this one was an interesting one involving Bitwise logic.

Aaron Bertrand ◆ August 1, 2012

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Best approaches for running totals – updated for SQL Server 2012

Usually, changing a cursor to a set-based operation is sound advice, but there are some exceptions, like the one described here (running totals).

Aaron Bertrand ◆ July 24, 2012

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