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