65 lines
1.7 KiB
Plaintext
65 lines
1.7 KiB
Plaintext
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[[norms]]
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=== `norms`
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Norms store various normalization factors -- a number to represent the
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relative field length and the <<index-boost,index time `boost`>> setting --
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that are later used at query time in order to compute the score of a document
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relatively to a query.
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Although useful for scoring, norms also require quite a lot of memory
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(typically in the order of one byte per document per field in your index, even
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for documents that don't have this specific field). As a consequence, if you
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don't need scoring on a specific field, you should disable norms on that
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field. In particular, this is the case for fields that are used solely for
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filtering or aggregations.
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Norms can be disabled (but not reenabled) after the fact, using the
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<<indices-put-mapping,PUT mapping API>> like so:
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[source,js]
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------------
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PUT my_index/_mapping/my_type
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{
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"properties": {
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"title": {
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"type": "string",
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"norms": {
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"enabled": false
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}
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}
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}
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}
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------------
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// AUTOSENSE
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NOTE: Norms will not be removed instantly, but will be removed as old segments
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are merged into new segments as you continue indexing new documents. Any score
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computation on a field that has had norms removed might return inconsistent
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results since some documents won't have norms anymore while other documents
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might still have norms.
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==== Lazy loading of norms
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Norms can be loaded into memory eagerly (`eager`), whenever a new segment
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comes online, or they can loaded lazily (`lazy`, default), only when the field
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is queried.
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Eager loading can be configured as follows:
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[source,js]
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------------
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PUT my_index/_mapping/my_type
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{
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"properties": {
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"title": {
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"type": "string",
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"norms": {
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"loading": "eager"
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}
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}
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}
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}
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------------
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// AUTOSENSE
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