Compression techniques

Data compression is the process of reducing an original data record to a smaller representation of that record. Because not all compression methods achieve the best possible compression results for a given data record, DATA PACKER/IMS provides the following techniques for compressing data:

  • Static Huffman
  • Custom Huffman
  • Shared Table
  • Hybrid
  • Basic Character
  • Extended Character
  • Hardware
  • Custom Hardware Dictionary

Static Huffman, Custom Huffman, Shared Table, and Hybrid techniques use the Huffman compression algorithm. Basic Character uses run-length encoding. Extended Character, Hardware, and Custom Hardware Dictionary use the Ziv-Lempel compression algorithm.

The percentage of compression achieved by each method depends on the nature of the data being compressed. The Trial utility provides a method for determining which compression technique is best suited to the data. Because compression is performed on a segment-by-segment basis, you can use several compression techniques within the same database.

 

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