Using Trace to Monitor and Audit Analysis Services - Microsoft SQL Server 2008 Analysis Services - page 780

The events of this query appear in Figure 38.14.

FIGURE 38.14 SQL Server Profiler shows the events for our new query.

Think back to the last query we sent. Now we have some events that occur after Query
Begin and Query Cube Begin . These are new for us: Calculate Non Empty Begin and Get
Data from Cache . The Calculate Non Empty Begin event indicates that the server has
entered the Calculate Non Empty code path. The purpose of this code path is to have the
server, as it resolves the query, eliminate any coordinates whose intersections contain no
results. Get Data from Cache indicates just what it seems to indicate: The data that is
retrieved is coming from a cache. The cache was created when our previous query read its
data. Therefore, you don't see any Progress Report events here.

Two events, Calculate Non Empty Begin and Get Data from Cache , occur before the seri-
alization events. The server can't populate the axes before it gets the result set, so the
server first has to issue a request for the result set.

Changing Your Query Just a Little More
The query execution in the preceding example is pretty compact. Now we'll change our
query just a little. Replace the Non Empty (an operator in MDX) with NonEmpty (a function
in MDX). The operator/function difference is important in MDX. You can find details
about these concepts in Chapter 11.