Compress option

Specifies whether the source data file data is compressed.

The valid values are as follows:
  • true or on
  • false or off
The default is false. The value of the option can be true or on only if you set the Format option to 'internal'.

zlib and zstd compression

The zstd compression support for external tables and nzbackup on same sized systems/data slices offers:
  • Up to 40% improvement in the backup rate compared to zlib.
  • At least a 25% reduction in CPU utilization.

The compress option accepts a string specifying the library to use for compression, either zlib or zstd.

For the zstd compression type, you might optionally pass a compression level in the range -131072 through 22.
  • If you do not pass the compression level, a default compression level 1 is used.
  • If you pass 0, the zstd compression library's default compression level.
Examples:
BOOLEAN
   compress true
   compress false
STRING
   compress 'true'
   compress 'false'
   compress 'zlib'
   compress 'zstd'
   compress 'zstd 5'
  • If you pass 'true', the default compression library is used. The default remains to be zlib.
Note:

Restoring backup taken with the zstd compression cannot be restored on different sized system, different data slices.

External table may only be loaded on a system with the same number of data slices as the source.

Unloaded zlib external tables remain compatible with PureData System for Analytics 7.2.1.7. zstd external tables will work only on Netezza Performance Server.

External tables created on PureData System for Analytics 7.2.1.7 continue to be compatible with Netezza Performance Server.