Compression[=options] NoCompression Data compression is applied to the user data unloaded to the internal (interchange) format file. Table rows, null byte vector and LIST OF BYTE VARYING data are compressed using either the LZW (Lempel-Ziv-Welch) technique or the ZLIB algorithm developed by Jean-loup Gailly and Mark Adler. Table metadata (column names and attributes) are never compressed and the resulting file remains a structured interchange file. Allowing compression allows the result data file to be more compact, using less disk space and permitting faster transmission over communication lines. This file can also be processed using the RMU Dump Export command. The default value is Nocompression. This qualifier accepts the following optional keywords (ZLIB is the default if no compression algorithm is specified): o LZW Selects the LZW compression technique. o ZLIB Selects the ZLIB compression technique. This can be modified using the LEVEL option. o LEVEL=number ZLIB allows further tuning with the LEVEL option that accepts a numeric level between 1 and 9. The default of 6 is usually a good trade off between result file size and the CPU cost of the compression. o EXCLUDE_LIST[=(column-name,...)] It is possible that data in LIST OF BYTE VARYING columns is already in a compressed format (for instance images as JPG data) and therefore need not be compressed by RMU Unload. In fact, compression in such cases might actually cause the output to grow. The EXCLUDE_LIST option will disable compression for LIST OF BYTE VARYING columns. Specific column names can be listed, or if omitted, all LIST OF BYTE VARYING columns will be excluded from compression. Only the user data is compressed. Therefore, additional compression may be applied using various third party compression tools, such as ZIP. It is not the goal of RMU to replace such tools. The qualifier RECORD_DEFINITION (or RMS_RECORD_DEF) is not compatible /COMPRESSION. Note that the TRIM option for DELIMITED format output can be used to trim trailing spaces from VARCHAR data.