Performance Tuning with SQL Server Dynamic Management Views

Chapter 5: Indexing Strategy and Maintenance
Figure 5.2: Both the master and AdventureWorks databases have an object identified by
object_id = 4 and index_id = 1.
This is why we had to filter the results by database in the WHERE clause in Listing 5.1. That
allows us to run this query under the context of any database and still receive the same
results. Alternatively, we could have used WHERE ddius.[database_id] = DB_ID().
However, we would then have had to run the query under the context of the Northwind
database in order to return the same results.
Occasionally, we may need to join to other indexing catalog views, such as sys.columns,
to find out details about specific columns in the index, such as their length, data type, and
so on. When we do so, we need to join via the intermediate view, sys.index_columns,
as shown in Figure 5.3.
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