Database Reference
In-Depth Information
Figure 15-5. Java Mission Control inspecting eXist
Cache Tuning
When the database is operating optimally, all caches will be completely filled with
data relevant to the most frequent node retrievals (and therefore query results). For
further background on how caching works in eXist,
“Paging and Caching” on page 85
is recommended preliminary reading. As eXist attempts to fill the entire cache space,
and this memory is taken away from the memory available to the rest of eXist,
administrators must be careful not to allocate caches that are sized in such a way that
they starve the rest of eXist of memory; this potentially leads to out-of-memory
errors and database crashes.
As
Figure 15-6
shows, it is recommended that the combined size of the general cache
(
cacheSize
) and collections cache (
collectionCache
) should not exceed one-third
of the total memory available to eXist, unless you are working in environments where
the total memory is greater than 8 GB. Even then, you should take care to ensure that
eXist is not memory-starved by its caches. A large cache does not automatically result
in better performance!
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