OLAP: Cache Monitor

Purpose

The OLAP Processor accesses two types of cache, the local cache and the global cache.

The local OLAP cache stores the results calculated by the OLAP Processor in the role area for each session. This is based on a single query instance at runtime.

Unlike the local cache, the global OLAP cache is cross-transactional. This makes it possible for various query instances to access the data stored here. This data is optimized for the OLAP Processor. This speeds up execution of the query due to faster access and the fact that the data has already been formatted.

At runtime, all drilldown states of the query - from a given calculation level - are cached locally to start with and then stored globally if required. The entries in the local cache are generated from the local runtime (cache) objects.

Various cache modes are supported for the global cache. These differ in terms of their persistence medium - the storage medium - and in the structure of the cache hierarchy that OLAP Processor uses to locate the individual objects in the cache. In the default setting, cache mode Query Aggregate (5) is set (also known as BLOB/Cluster Enhanced). Cache mode Main Memory Without Swapping (1) is the second most common cache mode.

Note

The other cache modes that are actually only offered for compatibility reasons - cache modes (2) to (4) - can be activated by setting the administration parameter Use Old Cache (see Cache Administration Parameters ). For more information about the old cache modes, see Cache Mode and Technical Information About Old Cache Modes .

The Cache Monitor screen provides you with information about the local cache, the global cache parameters, the amount of memory used by the query runtime objects and the current underlying cache structure.

Integration

To call the OLAP Cache Monitor (transaction RSRCACHE) from the SAP Easy Access screen, choose Business Explorer → BEx Monitor → OLAP: Cache Monitor. From the Query Monitor screen, you can call the OLAP Cache Monitor by pressing Cache Monitor.

The cache parameters are set in Customizing during implementation. The same settings can also be made in the OLAP Cache Monitor (see Cache Parameters ).

You can set the standard cache mode for an InfoProvider in Customizing. If you change these settings later, the changes do not affect existing queries for this InfoProvider. They only affect future queries created for this InfoProvider.
You can change the cache mode for a query in the Query Monitor screen (see Query Properties ).
Note
You can access an overview of the cache-relevant data for a query (important time stamps for example) from the Query Monitor screen by pressing Technical Info (see Technical Information ).

Features

Cache Parameters

Display cache parameters. The display is based on the settings made in Customizing. Example:

	Cache Parameters
	Cache Active
	Local Cache Size	50 MB
	Global Cache Size	200 MB
	Cache Persistence Mode	Cluster Table

Caution

Note that these parameters only relate to the main memory cache and not to the database caches.

Note

If you want to choose any of these settings, choose Cache Parameter.More information: Cache Parameters .

Cache Mode Functions

In addition to the cache parameters, you can also view the relevant data for all cache modes:

Pushbutton	Display
Technical Info	Displays cache-relevant information about the query run-time objects. For main memory cache modes it also displays the buffer status (Shared Memory)
Buffer Objects Hierarchical Display or Buffer Objects List Display	Displays the buffer objects In the default setting, the system displays buffer objects in a hierarchically structured query directory.More information: Cache Structure .

Pushbutton

Display

Technical Info

Displays cache-relevant information about the query run-time objects. For main memory cache modes it also displays the buffer status (Shared Memory)

Buffer Objects Hierarchical Display or Buffer Objects List Display

Displays the buffer objects

In the default setting, the system displays buffer objects in a hierarchically structured query directory.More information: Cache Structure .

Toolbar Functions

The following functions are available in the toolbar:

General Functions

Function	Information
(Refresh)
(Delete)	Deletes the cached data in accordance with the cache mode selected, deleting the buffer objects that you have chosen to display. If no selection has been made, the system does not delete any data. This function is useful when testing. Note To delete old entries in the cache, we recommend scheduling program RSR_CACHE_RSRV_CHECK_ENTRIES to run in background processing on a regular basis.See Cache Data Removal and Swapping .
Cache Parameter	See Global Cache Parameters .
Admin Parameter	See Cache Administration Parameters .

Functions for cache mode Main Memory Cache with/ Without Swapping

Function	Information
Buffer Monitor	Choose Buffer Monitoror Buffer Overviewto check whether enough cache memory is available for example. You can use Buffer Monitorto call the Buffer Monitoring Tool screen, which provides you with an overview of the buffers for your application server. The Buffer Overview contains the shared memory rows (buffer: Exp/ImpMem) relevant for the OLAP cache: Size: Maximum size of the cache memory in bytes Free bytes: Free cache memory in bytes Directory: Maximum number of directories (individual packages in the cache memory) Dir. Free: Number of free directories Efficiency: Degree to which requests can be met, in %, - corresponds to the Hit ratioin the Buffer Overview
Buffer Overview	The Tune Summary screen appears (transaction ST02). The shared memory row (buffer: Exp/Imp SHM) contains data relevant for the OLAP cache: Hitratio: [%] - corresponds to Efficiency in the Buffer Monitor Allocated: [kB] Free space: [kB] and [%] Dir. size: Entries Free directory: Entries and [%] Caution Note that both the number of bytes and the number of directories have a limiting effect. You can find out which of these values might be critical from the relationship between the respective maximum value and free capacity value. Note More information: Buffer Monitor .

Function

Information

Buffer Monitor

Choose Buffer Monitoror Buffer Overviewto check whether enough cache memory is available for example.

You can use Buffer Monitorto call the Buffer Monitoring Tool screen, which provides you with an overview of the buffers for your application server. The Buffer Overview contains the shared memory rows (buffer: Exp/ImpMem) relevant for the OLAP cache:

Size: Maximum size of the cache memory in bytes

Free bytes: Free cache memory in bytes

Directory: Maximum number of directories (individual packages in the cache memory)

Dir. Free: Number of free directories

Efficiency: Degree to which requests can be met, in %, - corresponds to the Hit ratioin the Buffer Overview

Buffer Overview

The Tune Summary screen appears (transaction ST02). The shared memory row (buffer: Exp/Imp SHM) contains data relevant for the OLAP cache:

Hitratio: [%] - corresponds to Efficiency in the Buffer Monitor

Allocated: [kB]

Free space: [kB] and [%]

Dir. size: Entries

Free directory: Entries and [%]

Caution

Note that both the number of bytes and the number of directories have a limiting effect. You can find out which of these values might be critical from the relationship between the respective maximum value and free capacity value.

Note

More information: Buffer Monitor .

Functions for cache modes Main Memory Cache with Swapping (into a file), and the persistence mode with Flat File Cache

Function	Information
Logical File Names	See Logical File Names (transaction FILE).
Directory Overview	The SAP Directories screen appears. Tip DIR_GLOBAL /usr/<SYSID>/global Double-click on the physical path to call the file display. If you have kept to the naming conventions, you can find your physical file under CACHE_<HOST>_<SYSID>_<PARAM_1> or CACHE_<SYSID>_<PARAM_1>. To find out more about defining logical and physical file paths and names, see Logical File Names .