Using Computed Columns For Pattern Matching

Erik Darling shows how you can use a computed column to speed up %something searches:

We were talking about computed columns, and one of our students mentioned that he uses computed columns that run the REVERSE() function on a column for easier back-searching.

What’s back-searching? It’s a word I just made up.

The easiest example to think about and demo is Social Security Numbers.

One security requirement is often to give the last four.

Obviously running this for a search WHERE ssn LIKE '%0000' would perform badly over large data sets.

One of the trickiest parts of performance tuning is understanding that the way people want to see data is not necessarily the way you should store the data.

Related Posts

See The Pernicious Effects Of Your UDFs

Pedro Lopes announces an improvement to SQL Server execution plan results in 2017 CU3: As I mentioned on yesterday’s post, with the recent release of SQL Server 2017 CU3, we released yet more showplan enhancements: you can see other posts related to showplan enhancements here. In this article I’ll talk about the second showplan improvement we worked on, to assist […]

Read More

The Downside Of Nested Views

Randolph West doesn’t mince words: Nested views are bad. Let’s get that out of the way. What is a nested view anyway? Imagine that you have a SELECT statement you tend to use all over the place (a very common practice when checking user permissions). There are five base tables in the join, but it’s fast enough. […]

Read More

Categories

January 2018
MTWTFSS
« Dec Feb »
1234567
891011121314
15161718192021
22232425262728
293031