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10ee0f2878
* Clarify that field data cache includes global ordinals * Describe that the cache should be cleared once the limit is reached * Clarify that the `_id` field does not supported aggregations anymore * Fold the `fielddata` mapping parameter page into the `text field docs * Improve cross-linking
35 lines
1.6 KiB
Text
35 lines
1.6 KiB
Text
[[modules-fielddata]]
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=== Field data cache settings
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The field data cache contains <<fielddata-mapping-param, field data>> and <<eager-global-ordinals, global ordinals>>,
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which are both used to support aggregations on certain field types.
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Since these are on-heap data structures, it is important to monitor the cache's use.
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[discrete]
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[[fielddata-sizing]]
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==== Cache size
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The entries in the cache are expensive to build, so the default behavior is
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to keep the cache loaded in memory. The default cache size is unlimited,
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causing the cache to grow until it reaches the limit set by the <<fielddata-circuit-breaker, field data circuit breaker>>. This behavior can be configured.
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If the cache size limit is set, the cache will begin clearing the least-recently-updated
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entries in the cache. This setting can automatically avoid the circuit breaker limit,
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at the cost of rebuilding the cache as needed.
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If the circuit breaker limit is reached, further requests that increase the cache
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size will be prevented. In this case you should manually <<indices-clearcache, clear the cache>>.
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`indices.fielddata.cache.size`::
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(<<static-cluster-setting,Static>>)
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The max size of the field data cache, eg `38%` of node heap space, or an
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absolute value, eg `12GB`. Defaults to unbounded. If you choose to set it,
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it should be smaller than <<fielddata-circuit-breaker>> limit.
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[discrete]
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[[fielddata-monitoring]]
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==== Monitoring field data
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You can monitor memory usage for field data as well as the field data circuit
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breaker using
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the <<cluster-nodes-stats,nodes stats API>> or the <<cat-fielddata,cat fielddata API>>.
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