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#### 6.1.7 `cache`

Usage:

       cache

Stores in memory or on disk a temporary copy of the table at this point in the pipeline. This can provide improvements in efficiency if there is an expensive step upstream and a step which requires more than one read of the data downstream. If you see an error like "Can't re-read data from stream" then adding this step near the start of the filters might help.

The output table contains no code-level reference to the input table, so this filter can also be useful when managing tables that have become deeply nested as the result of successively applying many STILTS operations.

The result of this filter is guaranteed to be random-access.

See also the `random` filter, which caches only when the input table is not random-access.

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STILTS - Starlink Tables Infrastructure Library Tool Set
Starlink User Note256
STILTS web page: http://www.starlink.ac.uk/stilts/
Author email: m.b.taylor@bristol.ac.uk
Mailing list: topcat-user@jiscmail.ac.uk