Archiving and Restoring Tables Using Temperature-based Compression - Teradata Database

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Archiving and Restoring Tables Using Temperature-based Compression

Tables compressed with automatic temperature-based block-level compression usually restore to the same temperature and compression status they had originally. However, this may not happen if the tables are restored onto a different system.

When you specify a query band TVSTEMPERATURE option, it overrides the original temperature (and, therefore, compression status) of the data that was archived.

To be sure that you have enough space for the restore, you can:

  • Try the restore using the same amount of space that was required on the source system. There is a good chance that the authorized space is sufficient. Do this only if the restore is not expected to take a long time.
  • Authorize the destination database for the amount of storage required if all the data is uncompressed (or as much as possible). To determine this amount, use the Ferret command UNCOMPRESS ESTIMATE.
  • Specify a query band option of COLD if there is not enough space on the destination system to authorize the potential uncompressed size of the data. This causes all the data in the table to be restored compressed if automatic temperature-based compression is enabled for the table on both the archive and restore system. While this may compress more data than required, at least the data can be successfully restored. Over time, the frequently accessed data in the table will warm up and be decompressed.