Specifying file compression options

Use the File Options tab in the Extract Service Editor to specify options for compressing the extract file or extracted tables.

You can specify the following options:
  • Indicate if the file or specific tables are compressed.
  • For each table, you can choose to use a compression threshold or compress as much as possible. The threshold value is the minimum amount of reduction in size that you expect to achieve by compressing the table. Enter a value in the range 1 - 99 to set a threshold value for that table.

The following compression methods are available for a file:

Inline Compression
Data is compressed as it is extracted and before it is written to the file. Inline compression has lower I/O, when compared with post compression, but uses database resources for the duration of the extract service.

Inline Compression requires less storage resources during the extract process when compared to post compression.

Post Compression

Data is extracted and written to an uncompressed file. In a second step, Optim™ reads the uncompressed file, and writes a compressed version of the file. The benefit of post compression is that database connections are closed earlier with post compression than with inline compression. However, with post compression the total elapsed time is increased because the uncompressed file must be closed, read, and then a new compressed version created.

Sites having concerns about database resource contention may find post compression useful as it shortens the time database resources are needed. However, post compression increases the elapsed time and storage requirements for processing the extract service. Although increased storage is necessary during the compression operation, that temporary storage required will be released when the compression is completed.

To specify file compression options:

  1. Expand a folder in the Directory Explorer that contains the extract service, expand the Extract Services node, and double-click the extract service to edit. The Extract Service Editor opens.
  2. Select the File Options tab.
  3. Edit the service processing options.
  4. Save the extract service.


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