Cache defines whether to enable
search result cache to improve performance.
This command is obsolete and should be used.
Starting from the version 3.3.8,
the Cache command was superseded by
new search result cache implementation which is
controlled by the
parameter to DBAddr. The new implementation supports automatic
invalidation of the outdated results, as well as the
"search in found feature"
(also often referenced as "refine your search").
The default value is no.