Problem Note 44277: Final subquery to satisfy a query against a SAS® OLAP cube might be unnecessary and impact performance
By default, in order to satisfy a query against an OLAP cube, the SAS OLAP Server performs subqueries to obtain the data for each axis independently. It then submits a final subquery to complete the query result set.
In some cases, the last subquery to the physical data is redundant and might unnecessarily increase the response time to return the result set when the result set could instead be retrieved from the existing subquery cache.
Situations where this could occur include the following:
- when there are only measures on one axis and a subquery has already been performed on the other axis
- if there is only one axis in the query and it has had its initial subquery performed
Consider the following example:
SELECT
[Measures].[TOTAL_AMOUNT] on columns,
NON EMPTY
ORDER( [PRODUCT].[All PRODUCT].CHILDREN ,
[Measures].[TOTAL_AMOUNT], DESC)
ON rows
FROM [ProductsCube]
This query produces the following two subqueries:
select distinct CATEGORY, S_TOTAL_AMOUNT from OLAPSIO.CAT
select distinct CATEGORY, S_TOTAL_AMOUNT from OLAPSIO.CAT
In this case, the second subquery could be avoided since the data for the final subquery is already available in the subquery cache.
Click the Hot Fix tab in this note to access the hot fix for this issue. Once the hot fix is applied, the final subquery will be evaluated to see if the result set can be returned from the subquery cache.
Operating System and Release Information
SAS System | SAS OLAP Server | z/OS | 9.2 TS2M0 | 9.3 TS1M1 |
Microsoft® Windows® for 64-Bit Itanium-based Systems | 9.2 TS2M0 | 9.3 TS1M1 |
Microsoft Windows Server 2003 Datacenter 64-bit Edition | 9.2 TS2M0 | 9.3 TS1M1 |
Microsoft Windows Server 2003 Enterprise 64-bit Edition | 9.2 TS2M0 | 9.3 TS1M1 |
Microsoft Windows XP 64-bit Edition | 9.2 TS2M0 | 9.3 TS1M1 |
Microsoft® Windows® for x64 | 9.2 TS2M0 | 9.3 TS1M1 |
Microsoft Windows Server 2003 Datacenter Edition | 9.2 TS2M0 | 9.3 TS1M1 |
Microsoft Windows Server 2003 Enterprise Edition | 9.2 TS2M0 | 9.3 TS1M1 |
Microsoft Windows Server 2003 Standard Edition | 9.2 TS2M0 | 9.3 TS1M1 |
Microsoft Windows Server 2003 for x64 | 9.2 TS2M0 | 9.3 TS1M1 |
Microsoft Windows Server 2008 for x64 | 9.2 TS2M0 | 9.3 TS1M1 |
Microsoft Windows XP Professional | 9.2 TS2M0 | 9.3 TS1M1 |
Windows Vista | 9.2 TS2M0 | 9.3 TS1M1 |
Windows Vista for x64 | 9.2 TS2M0 | 9.3 TS1M1 |
64-bit Enabled AIX | 9.2 TS2M0 | 9.3 TS1M1 |
64-bit Enabled HP-UX | 9.2 TS2M0 | 9.3 TS1M1 |
64-bit Enabled Solaris | 9.2 TS2M0 | 9.3 TS1M1 |
HP-UX IPF | 9.2 TS2M0 | 9.3 TS1M1 |
Linux | 9.2 TS2M0 | 9.3 TS1M1 |
Linux for x64 | 9.2 TS2M0 | 9.3 TS1M1 |
OpenVMS on HP Integrity | 9.2 TS2M0 | 9.3 TS1M1 |
Solaris for x64 | 9.2 TS2M0 | 9.3 TS1M1 |
*
For software releases that are not yet generally available, the Fixed
Release is the software release in which the problem is planned to be
fixed.
Type: | Problem Note |
Priority: | high |
Date Modified: | 2011-09-19 09:01:00 |
Date Created: | 2011-09-13 11:26:57 |