Global Cache Parameters 
Use
Global cache parameters are the global settings for the OLAP cache (they are valid system-wide).
The following table provides an overview of the different OLAP cache types:
OLAP Cache Type |
Description |
Cross-transaction application buffer, in which the query navigation states and query results that were calculated using the OLAP processor are stored on the application server instance. With similar query requests, the OLAP processor can access the data stored in the cache. Query execution is accelerated when the OLAP processor can read data from the cache. This is because the cache can be accessed much quicker compared with InfoProvider accesses |
|
Local cache |
Local OLAP processor cache, in which the results calculated by the OLAP processor are stored in the roll area for each session |
The two types of cache (local and global) represent two alternatives: Either use the global cache, or if this is not possible or desired, use the local cache.
Irrespective of this the global cache also shares some properties of the local cache: For instance, data is similarly retained in the roll area as long as it is required by the OLAP processor. On the other hand, the local cache size also has a significance in the global cache: With both types of cache, cache objects that are no longer needed are deleted from the roll area if the local cache size is exceeded. However, as deleting objects is only possible with objects that are no longer required by the OLAP processor, the total size of cache objects in the roll area can exceed the local cache size.
Integration
The global cache parameters are determined centrally during implementation of the BI system.
For more information, see the Implementation Guide (IMG) for SAP NetWeaver ® Business Intelligence ® Reporting-Relevant Settings ® General Reporting Settings in the Business Explorer ® Global Cache Settings.
It may emerge from the evaluation of data displayed in the OLAP Cache Monitor that the global cache parameters need to be adjusted to fit system demands. In this case, you are able to change these settings later.
You can reach
the Change “OLAP Cache Parameters“ View: Detail screen from
the Cache Monitor screen, by choosing 
Cache Parameter. Make the required changes.
Features
Cache Inactive
Setting this parameter means that the cross-transactional cache is deactivated centrally.
Local Size MB: Local Cache Size in MBytes
This parameter determines the memory size of the local OLAP processor cache.
Note that the local cache is used, for example, in the following cases:
· When the cross-transactional cache has been deactivated (see the parameter Cache Inactive).
· When the cache was deactivated for the InfoProvider (for all future queries) or the query (see Cache Mode)
· If you determine during runtime that caching cannot take place (see Technical Information under Cache-Relevant Data: Query Can Use Cache)
Global Size MB: Global Cache Size in MBytes
This parameter determines the maximum memory usage for all objects in the cross-transaction cache for the cache modes Main Memory Cache With or Without Swapping. For more information, see Cache Mode.
Memory consumption means the amount of memory used by the objects in the shared memory. The actual memory consumption in the shared memory is generally higher because, in addition to the compressed cache objects in the cross-transactional application buffer, administrative data (from SAP Web AS pages) is also written there.
The actual size of the cross-transactional cache depends on the size settings of the cross-transactional application buffer: The maximum cache size is the minimum from the Size Global MB parameter and the memory size that is actually available in the cross-transactional application buffer.
Persistence Mode
The persistence mode allows you to determine whether and in what form cache data is to be stored:
Cache mode Main Memory Cache with or Without Swapping
The Persistence Mode parameter determines what happens to the data in the cache if the memory reaches its maximum size. A proportion of the data must either be removed or swapped. A process using the Least Recently Used (LRU) algorithm determines which data is affected by this.
Cache modes Persistent Cache per Application Server or Cross-Application Server
The Persistence Mode parameter determines whether the data is to be stored in a file (flat file) or in a database table.
The following table offers an overview of how the available persistence modes can be used:
Persistence modes
Persistence Mode |
Cache modes Main Memory Cache with or Without Swapping |
Cache modes Persistent Cache per Application Server or Cross-Application Server |
Inactive |
When the cache memory has been exhausted, data is removed, that is deleted, from the memory (corresponds to cache mode Main Memory Cache Without Swapping). |
|
Flat File |
In cache mode Main Memory with Swapping: When the cache memory has been exhausted, data is stored in a file (see Flat File Name). |
The cached data is stored as a file in a directory on the application server or cross-application server in the network (see Flat File Name and Over-Arching File). |
Database Table: · Cluster table · Transparent table (BLOB) |
In cache mode Main Memory Cache with Swapping: When the cache memory is exhausted, data is stored in the database in a non-transparent cluster table or in a transparent table with BLOB (Binary Large Object). |
The cached data is stored in the database as a non-transparent cluster table or as a transparent table with BLOB (Binary Logical Object). Cluster tables differ in whether they have the application server in the key. This depends on the cache mode |
If you select the initial entry, in other words, a blank entry and none of the options listed above, the system sets the persistence mode to inactive and displays this accordingly on the Cache Monitor screen in the Cache Parameters screen area.
Flat File Name: Cache Persistence Logical File Name
Logical file name under which flat files are stored (see Logical File Names).
BW_OLAP_CACHE
The following table offers an overview of these parameters and their usage:
Parameter flat file name
Cache Mode |
Meaning |
Main Memory Cache with Swapping |
The flat file name specifies the logical file path under which removed data is stored after swapping |
Persistent Cache per Application Server |
If the cache data is held in a file the flat file name specifies the logical file path under which all the data is stored |
Over-Arching File: Cache Persistence Logical File Name
Logical file path under which data is stored (see Logical File Names).
BW_OLAP_CACHE_SPAN
The following table offers an overview of these parameters and their usage:
Over-Arching File Parameter
Cache Mode |
Meaning |
Cross-Application Server Persistent Cache |
The flat file name specifies the logical file path under which all data is stored. The path is not dependent on the application server |