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Within this blog (maybe

there will be more posts) I want to focus on performance issues with SAP Business Warehouse Accelerator (BWA) .

Some experienced BWA admin
may just laugh seeing this post. However there are some customers out there not
knowing about this feature of BWA. The fact is that FEMS compression is BWA
feature aimed for reduction of transport costs. This is meant in terms of an
intelligent compression schema. Moreover elimination of duplicates in query
results directly on the BWA side is enabled. Setting this feature ON can
improve performance of BWA.

FEMS are Formula EleMent Selections (or also Finite EleMent Solver) carrying information about structure

elements where certain value belongs. Database and BWA are giving records by

exploding structure elements. These records are than assigned to correct

structure elements by the OLAP. FEMS compression enables merge of duplicate

structure elements in BWA part and makes OLAP par being able to process this information.

All together there is a reduction of information traffic between BWA and BW

backend.+). Open screen area Landscape -> Ini. See current

settings in* *configuration file TREXIndexServer.ini in its



to set this setting? </p><p>See above *configuration file +TREXIndexServer.ini.

Add parameter in to file: fems_compression = on.+

In general settings FEMS

compression ON is always advisable. Setting this ON has no influence on BWA’s indices

size. You may only be asked by SAP to switch it off in situation that you

raised BWA problem message (e.g. wrong data provided by BWA based query vs. proper

data given by same query running without BWA) to SAP via SMP channel. If issue cannot be quickly

analyzed SAP may ask you to switch compression off to help them isolate issue.

* *

sources used for this blog:*

FEMS Compression

documentation: Enabling 'FEMS Compression'

BIA BLOG Series, Part VIII: Improvements and major parameter changes for BI Accelerator

SAP Note 1074953 -
FEMS, BIA optimization

Note 1118425 - BIA
7.00: Activate performance feature FEMS compression