SQL Indexes Archives - Page 6 of 6

Hit-Highlighting in Full-Text Search

Hit-highlighting is a feature that many people wish SQL Server's Full-Text Search would support natively. This is where you can return the entire document (or an excerpt) and point out the words or phrases that helped match that document to the search. Doing so in an efficient and accurate manner is no easy task, as I found out first hand.

Aaron Bertrand ◆ September 24, 2012

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How much impact can a data type choice have?

I've long been a proponent of choosing the correct data type. I've talked about some examples in a previous "Bad Habits" blog post, but this weekend at SQL Saturday #162 (Cambridge, UK), the topic of using DATETIME by default came up. In a conversation after my T-SQL : Bad Habits and Best Practices presentation, a user stated that they just use DATETIME even if they only need granularity to the minute or day, this way the date/time columns across their enterprise are always the same data type. I suggested that this might be wasteful, and that the consistency might not be worth it, but today I decided to set out to prove my theory.

Aaron Bertrand ◆ September 13, 2012

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What is the most efficient way to trim time from datetime?

The most common need for stripping time from a datetime value is to get all the rows that represent orders (or visits, or accidents) that occurred on a given day. However, not all of the techniques that are used to do so are efficient or even safe. If you want a safe range query that performs well, use an open-ended range or, for single-day queries on SQL Server 2008 and above, use CONVERT(DATE). Read on to discover why…

Aaron Bertrand ◆ September 5, 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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