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Procedure documentation Setting the Maximum Memory Allocation Locate the document in its SAP Library structure

Use

The maximum memory allocation parameter is used to set a limit on the amount of memory that will be allocated by DART on the application server to build data segment indexes. During record extraction for a particular data segment, index records are built and stored until the segment is completed. Then the index records are sorted and added to the segment in the extract. Index records are initially kept in memory. When index records are sorted in memory, the system may require auxiliary disk space to temporarily store sorting information. Even if enough memory to store the index is available, sorting the temporary index data requires a much larger amount of temporary disk space than the size of the index itself.

For this reason, a DART configuration parameter exists that limits the amount of index data that is kept in memory. You are required to enter the upper limit of how much memory can be allocated to the application server in megabytes (only if the default of 50 MB is not enough). If this limit is exceeded, index data will be stored in the auxiliary database table TXW_INDEX. When the index data is complete, it will be read from this table and extracted. Then the table is cleared. This limits memory consumption and also offloads the sorting process to the database, obviating the need for sort space on the application server.

Experience shows that using the TXW_INDEX table can add approximately 30% to execution time. Performance is best if only application server memory is used. It becomes important to know the extent of index memory DART will need. You can use the file size worksheet to estimate the size of the temporary index memory and temporary disk sort space that will be required.

To avoid the use of the temporary index table TXW_INDEX, set the maximum index memory allocation (extract configuration) to a value larger than the required temporary index memory. The temporary sort space is only used if the temporary index memory is below the limit set in the extract configuration. For example, if the file size worksheet estimates that 46 MB of index memory is required and the extract configuration specifies a limit of 50 MB for index memory allocation; this means that the extraction run will only use application server memory, and the database table TXW_INDEX will not be used to temporarily store index data. The temporary sort files will be located in the directory that is assigned in the system profile of each application server.

Only one job at a time can use the TXW_INDEX table. If more jobs run in parallel, all but one are automatically using application server memory. If you need to run DART extraction jobs in parallel, you should allocate them to separate application servers and make sure enough memory is available.

Procedure

Setting the Maximum Memory Allocation

  1. From the main DART screen choose Configuration ® Data extracts.
  2. Choose Display <-> Change.
  3. Choose Technical Settings.
  4. Enter the Maximum memory allocation for index(MB).
  5. Choose Save.

 

 

 

 

 

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