Thinking About Index Design

Jeremiah Peschka looks at a scenario in which a heap might be superior to a clustered index:

In this case, we have to assume that Event IDs may be coming from anywhere and, as such, may not arrive in order. Even though we’re largely appending to the table, we may not be appending in a strict order. Using a clustered index to support the table isn’t the best option in this case – data will be inserted somewhat randomly. We’ll spend maintenance cycles defragmenting this data.

Another downside to this approach is that data is largely queried by Owner ID. These aren’t unique, and one Owner IDcould have many events or only a few events. To support our querying pattern we need to create a multi-column clustering key or create an index to support querying patterns.

This result is not intuitive to me, and I recommend reading the whole thing.

Related Posts

Column Order Matters For Indexes

Bert Wagner violates Betteridge’s Law of Headlines: When beginning to learn SQL, at some point you learn that indexes can be created to help improve the performance of queries. Creating your first few indexes can be intimidating though, particularly when trying to understand what order to put your key columns in. Today we’ll look at […]

Read More

Creating Indexed Views

Eduardo Pivaral shows how to create a fairly simple indexed view: Views help our query writing by simplifying writing the same sentences and/or aggregations over and over again, but it has a drawback, the views just store our query definition, but the performance is not improved by using them. Since SQL Server 2008, the option […]

Read More

Categories

August 2016
MTWTFSS
« Jul Sep »
1234567
891011121314
15161718192021
22232425262728
293031