57 lines
2.1 KiB
Plaintext
57 lines
2.1 KiB
Plaintext
[[index-modules-cache]]
|
|
== Cache
|
|
|
|
There are different caching inner modules associated with an index. They
|
|
include `filter` and others.
|
|
|
|
[float]
|
|
[[filter]]
|
|
=== Filter Cache
|
|
|
|
The filter cache is responsible for caching the results of filters (used
|
|
in the query). The default implementation of a filter cache (and the one
|
|
recommended to use in almost all cases) is the `node` filter cache type.
|
|
|
|
[float]
|
|
[[node-filter]]
|
|
==== Node Filter Cache
|
|
|
|
The `node` filter cache may be configured to use either a percentage of
|
|
the total memory allocated to the process or an specific amount of
|
|
memory. All shards present on a node share a single node cache (thats
|
|
why its called `node``). The cache implements an LRU eviction policy:
|
|
when a cache becomes full, the least recently used data is evicted to
|
|
make way for new data.
|
|
|
|
The setting that allows one to control the memory size for the filter
|
|
cache is `indices.cache.filter.size`, which defaults to `20%`. *Note*,
|
|
this is *not* an index level setting but a node level setting (can be
|
|
configured in the node configuration).
|
|
|
|
`indices.cache.filter.size` can accept either a percentage value, like
|
|
`30%`, or an exact value, like `512mb`.
|
|
|
|
[float]
|
|
[[index-filter]]
|
|
==== Index Filter Cache
|
|
|
|
A filter cache that exists on the index level (on each node). Generally,
|
|
not recommended for use since its memory usage depends on which shards
|
|
are allocated on each node and its hard to predict it. The types are:
|
|
`resident`, `soft` and `weak`.
|
|
|
|
All types support the following settings:
|
|
|
|
[cols="<,<",options="header",]
|
|
|=======================================================================
|
|
|Setting |Description
|
|
|`index.cache.filter.max_size` |The max size (count, not byte size) of
|
|
the cache (per search segment in a shard). Defaults to not set (`-1`),
|
|
which is usually fine with `soft` cache and proper cacheable filters.
|
|
|
|
|`index.cache.filter.expire` |A time based setting that expires filters
|
|
after a certain time of inactivity. Defaults to `-1`. For example, can
|
|
be set to `5m` for a 5 minute expiry.
|
|
|=======================================================================
|
|
|