[[query-cache]]
=== Node Query Cache

The results of queries used in the filter context are cached in the node query 
cache for fast lookup. There is one queries cache per node that is shared by all 
shards. The cache uses an LRU eviction policy: when the cache is full, the least 
recently used query results are evicted to make way for new data. You cannot 
inspect the contents of the query cache.

Term queries and queries used outside of a filter context are not eligible for 
caching.

By default, the cache holds a maximum of 10000 queries in up to 10% of the total 
heap space. To determine if a query is eligible for caching, {es} maintains a 
query history to track occurrences.

Caching is done on a per segment basis if a segment contains at least 10000 
documents and the segment has at least 3% of the total documents of a shard. 
Because caching is per segment, merging segments can invalidate cached queries.

The following setting is _static_ and must be configured on every data node in
the cluster:

`indices.queries.cache.size`::
    Controls the memory size for the filter cache , defaults to `10%`. Accepts
    either a percentage value, like `5%`, or an exact value, like `512mb`.

The following setting is an _index_ setting that can be configured on a 
per-index basis. Can only be set at index creation time or on a
<<indices-open-close,closed index>>:

`index.queries.cache.enabled`::
    Controls whether to enable query caching. Accepts `true` (default) or
    `false`.