Reclustering 

Use

Reclustering allows you to change the clustering of InfoCubes and DataStore objects that already contain data. You may need to make a correction if, for example, there are only a few data records for each of the value combinations of the selected MDC dimension and as a result the table uses an excessive amount of memory space. To improve the performance of database queries, you may want to introduce multidimensional clustering for InfoCubes or DataStore objects.

Integration

This function is only available for the database platform DB2 for Linux, UNIX, and Windows. You can use partitioning to improve the performance of other databases. For more information, see Partitioning.

Features

Reclustering InfoCubes

With reclustering, the InfoCube fact tables are always completely converted. The system creates shadow tables with a new clustering schema and copies all of the data from the original tables into the shadow tables. As soon as the data is copied, the system creates indexes and the original table replaces the shadow table. After the reclustering request has been successfully completed, both fact tables exist in their original state (name of shadow table) as well as in their modified state with the new clustering schema (name of original table).

You can only use reclustering for InfoCubes. Reclustering deactivates the active aggregates of the InfoCubes; they are reactivated after the conversion.

Reclustering DataStore Objects

Reclustering completely converts the active table of the DataStore object. The system creates a shadow table with a new clustering schema and copies all of the data from the original table into the shadow table. As soon as the data is copied, the system creates indexes and the original table replaces the shadow table. After the reclustering request has been successfully completed, both active tables exist in their original state (name of shadow table) as well as in their modified state with the new clustering schema (name of original table).

You can only use reclustering for standard DataStore objects and DataStore objects for direct update. You cannot use reclustering for write-optimized DataStore objects. User-defined multidimensional clustering is not available for write-optimized DataStore objects.

Monitoring

You can monitor the clustering request using a monitor. The monitor shows you the current status of the processing steps. When you double-click, the relevant logs appear. The following functions are available in the context menu of the request or editing step:

●      Delete: You delete the clustering request. It no longer appears in the monitor and you cannot restart. All tables remain in their current state. This may result in inconsistencies in the InfoCube or DataStore object.

●      Reset Request: You reset the clustering request. This deletes all the locks for the InfoCube and all its shadow tables.

●      Reset Step: You reset the canceled editing steps so that they are reset to their original state.

●      Restart: You restart the clustering request in the background.

Background Information About Copying Data

By default, the system copies a maximum of six processes in parallel. The main process splits dialog processes in the background. These dialog processes each copy small data packages and finish with a COMMIT. If a timeout causes one of these dialog processes to terminate, you can restart the affected copy operations after you have altered the timeout time. To do this, choose Restart Reclustering Request.

Activities

You access reclustering in the Data Warehousing Workbench under Administration or in the context menu of your InfoCube or DataStore object.

You can schedule repartitioning in the background by choosing Initialize. You can monitor the clustering requests by choosing Monitor.