240 IBM Cognos Dynamic Cubes
The other query does not route because the measures do not match, as shown in
Example 8-12.
Example 8-12 Cross-tab report user query (2)
<event component="XQE" group="ROLAPQuery.AggregateStrategy"...>
<![CDATA[<aggregateAnalysis>
<v5Report name="unknown"/>
<originalQuery>
<measures>
<measure name="Unit sale price"/>
<measure name="Unit price"/>
<measure name="Unit cost"/>
<measure name="Gross profit"/>
</measures>
<levels>
<level name="Year" dimension="Time" hierarchy="Time"/>
</levels>
</originalQuery>
<aggregatesConsidered/>
<aggregatesNotMatching>
<aggregateCube name="gosldw_sales2">
<ordinal value="1"/>
<reason value="measureNotMatching">
<measure name="Unit sale price"/>
</reason>
</aggregateCube>
</aggregatesNotMatching>
</aggregateAnalysis>
]]></event>
In this example, because one of the two decomposed queries was routed to an aggregate
cube, the aggregate table hit rate is 50%.
8.6 Cache Priming Techniques
This section describes two approaches for ensuring that relevant data is in the Cognos
Dynamic Cubes caches to accelerate query performance:
preloading and priming.
8.6.1 Preloading the caches
Preloaded caches are those that are loaded with data that is based on metadata definitions
that are associated with the cube model data source, and are loaded at cube start, cube
restart, and cache refreshes. In Cognos Dynamic Cubes, the member cache and the
aggregate cache are both considered preloaded caches. After they are built and loaded from
definition, the member cache and the aggregate cache are neither affected by nor grow
based on query usage. Only changes to the cube model or changes to the set of in-memory
aggregates that are saved for the cube will affect these caches at the next cube start.
The member cache is always loaded. The size of the member cache is a key factor in
determining overall JVM heap size and needs for the cube. For more information about JVM
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