In This Section:
Oracle Hyperion Enterprise Performance Management System Backup and Recovery Guide for information on backing up an aggregate storage application
See these security-related topics:
About Essbase Native Security Mode in the Oracle Essbase Database Administrator's Guide
“Managing User/Group Permissions for Applications and Databases”
in the Oracle Essbase Administration Services Online Help
“Privileges and Roles” in the Oracle Essbase Technical Reference
Tablespaces help optimize data file and work file storage and retrieval. Tablespaces define location definitions that map data artifacts, such as aggregate views and aggregations, to files. Each application directory contains directories for four tablespaces:
Tablespace names are case-sensitive, regardless of operating system. You cannot change the location or size of metadata and log. For default and temp you can specify multiple locations and sizes, and you can define tablespace properties:
You can modify or delete file locations used to store information within a tablespace if the locations are empty.
When space is needed, Essbase checks file locations (in numerical order) and, when space is found, starts writing. When all locations are used, no space is available, and an error is returned. When database values are cleared, tablespace files shrink, releasing disk space. Work files that are no longer needed are deleted, making space available for other programs.
Based on the maximum size specified for files, Essbase writes multiple files; for example, ess00001.dat, ess00002.dat, and so on. If you back up database files to other media, do not set a maximum tablespace file size greater than the size that the media can handle.
To define tablespaces, use a tool:
UNIX platforms enforce a maximum 2 GB file limit. If, during a data load or an aggregate build, the .dat file limit is exceeded, this message is displayed: "Failed to extend file: file exceeds maximum file size for this system." Essbase closes the data file, creates the next file (essn+1), and continues.
When an aggregate storage outline is started, a small area in memory is allocated as the aggregate storage cache for the relevant application. As additional cache area is needed, the cache size incrementally increases until the maximum cache size is used or the operating system denies additional allocations.
You can view the current aggregate cache memory allocation and the maximum aggregate cache size setting. Changing the setting may optimize memory use. The default maximum cache size, 32 MB, is the minimum setting size. You can use the size of input-level data to determine when to increase the maximum size for the cache. Administration Services and MaxL display the size of input-level data as the aggregate storage database property: Size of level 0 values.
A 32 MB cache setting supports a database with approximately 2 GB of input-level data. If the input-level data size is greater than 2 GB by some factor, the aggregate storage cache can be increased by the square root of the factor. For example, if the input-level data size is 3 GB (2 GB * 1.5), multiply the aggregate storage cache size of 32 MB by the square root of 1.5, and set the aggregate cache size to the result: 39.04 MB.
For aggregation materialization performance, consider the number of threads set for parallel calculation. The aggregation materialization process uses multiple threads that divide the aggregate storage cache. Increasing the number of threads specified in the CALCPARALLEL configuration setting for aggregate storage applications or databases may require an increase in aggregate storage cache size. See the CALCPARALLEL configuration setting in the Oracle Essbase Technical Reference.
Setting the number of threads higher than the number of processors may improve aggregate storage application performance.
To set aggregate storage cache size, use a tool:
You might encounter the following message while building aggregate views on an aggregate storage database:
For better performance, increase the size of aggregate storage cache
This message sometimes occurs when an aggregate storage database is larger than a few hundred million input cells.
To improve the performance of building aggregates, take the following steps.
Increase the size of the aggregate storage cache to at least 512 MB or 20% of the input data size, whichever is smaller. (If the cache setting is already greater than this amount, proceed to the next step.) You can use Administration Services Console or the following MaxL command:
alter application appname set cache_size xMB
This setting takes effect after you restart the application.
If you still see the message when building aggregate views after increasing the aggregate storage cache, use the ASOSAMPLESIZEPERCENT configuration setting. Syntax:
ASOSAMPLESIZEPERCENT [appname [dbname]] n
Gradually increase the n value until the message disappears and optimal aggregation performance is reached. For a database that contains:
20 million input cells, start with 5%
100 million cells, start with 1%
More than 1 billion cells, start with 0.1%
Clear the aggregate views; then reselect and rebuild them. If the message still appears, increase the setting and try again.
Performance of building aggregate views may not improve until the message no longer occurs. When the message no longer occurs and performance no longer improves, stop increasing the setting.
If you increase the ASOSAMPLESIZEPERCENT setting too high, performance will start to degrade again. The optimal setting for a database larger than 1 billion cells will probably be less than 3%. For more information on ASOSAMPLESIZEPERCENT, see the Oracle Essbase Technical Reference.
If a standard dimension is tagged as multiple hierarchies enabled, it contains multiple hierarchies. The generation 2 members are the top members of the hierarchies. For example, the Products dimension in ASOsamp.Sample contains two hierarchies. The top members are the generation 2 members All Merchandise and High End Merchandise.
Table 235. Aggregate Storage Restructuring Levels
Storage requirement is up to three times the size of the affected views. Such aggregate views normally exist only if you used query tracking to select views based on usage. See Selecting Views Based on Usage.
On nonattribute dimensions without stored level 0 members (for example, all level 0 members are shared or have formulas), add a child or child branch without changing the number of levels in the hierarchy and without crossing a power of 2 boundary.
If the number of levels in the hierarchy changes, Essbase clears all aggregate views and performs a full outline restructure. Performance impact is Very High.
If the number of levels in the hierarchy does not change, but adding a child or child branch crosses a power of 2 boundary, Essbase performs a full outline restructure. Performance impact is High.
Performs light outline restructure.
On nonattribute dimensions with stored level 0 members:
Clears aggregate views, and performs full outline restructure
This sections contains examples of the more complicated outline changes described in Table 235, Aggregate Storage Restructuring Levels.
Adding a child member does not change the number of levels (two) in the hierarchy. Adding a seventh or eighth child member at the end is allowed; however, adding a ninth child member crosses the power of 2 boundary (see Example: Addition of Child Members), requiring a full outline restructure.
In the Product dimension in ASOsamp.Sample, renaming Photo Printers to Printers and adding child members increases the number of levels in the All Merchandise hierarchy from four to five. When the outline is saved, Essbase clears all aggregate views and performs a full outline restructure.
If you delete the shared member Orange under Drinks by Category and do not delete its nonshared member under Drinks, the alternate hierarchy Drinks by Category is no longer a replica of the Drinks hierarchy. When the outline is saved, Essbase clears all aggregate views and performs a full outline restructure.
If you delete the shared and nonshared Orange members, the alternate hierarchy Drinks by Category remains a replica of the Drinks hierarchy. When the outline is saved, Essbase performs a full outline restructure but does not clear aggregate views.
In ASOsamp.Sample, adding a child member under Systems in the All Merchandise hierarchy increases the number of children under Systems to three, crossing the power of 2 boundary. When the outline is saved, Essbase performs a full outline restructure.
However, adding a child member under Computers and Peripherals increases the number of children under Computers and Peripherals from three to four. Adding a fourth child, which must be added after the existing members, does not cross the boundary of 2 or 4. The child must be added after existing members. When the outline is saved, Essbase performs a light restructure.
In ASOsamp.Sample, adding a child branch under Computers and Peripherals in the All Merchandise hierarchy increases the number of children to four. Adding this child, which must be added after the existing members, does not cross the power of 2 boundary. The new member, called Other Peripherals, has two children. Systems (which is a sibling of Other Peripherals) has two children. Adding the child branch stays within the power of 2 boundary for children of sibling members at the same level. When the outline is saved, Essbase performs a light restructure.
Adding a child branch with three child members crosses the power of 2 boundary and may require that Essbase perform a full outline restructure. However, if Systems already had three members, the power of 2 boundary would be four and, at most, four children can be added to Other Peripherals without triggering a full outline restructure.
If you have read permission for an aggregate storage database, you can export level 0 data from the database to a specified text file. The export file contains only uncompressed data, not control, outline, or security information. During data export, users can connect to Essbase Server and perform read-only operations on the database.
To avoid creating export files larger than 2 GB, Essbase may create multiple export files that include a number suffix in the name, as follows: _1, _2, and so on. For example, if the first file name is /home/exportfile.txt, the next file is /home/exportfile_1.txt.