You experience a decrease in query performance after you perform an incremental process on a virtual dimension in SQL Server 2000 Analysis Services (896864)
The information in this article applies to:
- Microsoft SQL Server 2000 Analysis Services
Bug #: 14448 (Plato7x) Plato7x:14448 SYMPTOMSWhen you run a query against Microsoft SQL Server 2000
Analysis Services build 8.00.0909 or a later build, you may experience a
decrease in query performance. The problem occurs when the following
conditions are true:
- The query uses a virtual dimension or a changing
dimension.
- You run the query after you perform an incremental
process on a virtual dimension.
Note You can examine the build version of SQL Server 2000 Analysis
Services by verifying the file version of the C:\Program files\Microsoft
Analysis Services\Bin\Msmdsrv.exe file. CAUSESQL Server 2000 Analysis Services build 8.00.0909 and later
builds contain changes to correct a problem where indexes and aggregations for
virtual dimensions were not correctly updated after an incremental update on
the virtual dimension. The solution that is introduced in build 8.00.0909
requires that the flexible aggregations and indexes be rebuilt.
Flexible aggregations are aggregations that apply to any non-all and
non-leaf levels in virtual, parent-child, and changing dimensions. The flexible
aggregations and indexes are rebuilt by using the lazy indexing process. This
lazy indexing process runs on a background thread.
For large SQL
Server 2000 Analysis Services implementations, this lazy indexing process can
take a long time to finish. When the flexible aggregations and indexes are
rebuilt, queries that would generally benefit from these aggregations must read
data at the leaf levels of the involved dimensions. This behavior can cause a
decrease in query performance. RESOLUTIONTo help administrators reduce the effect of missing flexible
aggregations, SQL Server 2000 Analysis Services build 8.00.0950 and later
builds contain the ability for administrators to control the order that
partitions in a database are reindexed. Administrators can make sure that the
most frequently queried partitions are reaggregated and reindexed first.
For more
information about the partition prioritization in Analysis Services, click the
following article number to view the article in the Microsoft Knowledge Base: 843262
FIX: You may notice that the query
performance on an Analysis Services cube degrades temporarily after an
incremental update processes the virtual dimensions
REFERENCES For more information about the issue that is fixed in Analysis
Services hotfix build 8.00.0909, click the following article number to view the
article in the Microsoft Knowledge Base: 834490
FIX: MDX queries on a cube that
contains a virtual dimension may not reflect changes after the incremental
update on the virtual dimension
Modification Type: | Major | Last Reviewed: | 4/29/2005 |
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Keywords: | kbPerformance kbbug KB896864 kbAudITPRO kbAudDeveloper |
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