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Enhance documenation to explain that "_index_prefix" subfield must be added to `matched_fields` param for highlighting a main field. When doing prefix queries on fields that are indexed with prefixes, "_index_prefix" subfield is used. If we try to highlight the main field, we may not get any results. "_index_prefix" subfield must be added to `matched_fields` which instructs ES to use matches from "_index_prefix" to highlight the main field.
83 lines
1.8 KiB
Text
83 lines
1.8 KiB
Text
[[index-prefixes]]
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=== `index_prefixes`
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The `index_prefixes` parameter enables the indexing of term prefixes to speed
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up prefix searches. It accepts the following optional settings:
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[horizontal]
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`min_chars`::
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The minimum prefix length to index. Must be greater than 0, and defaults
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to 2. The value is inclusive.
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`max_chars`::
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The maximum prefix length to index. Must be less than 20, and defaults to 5.
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The value is inclusive.
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This example creates a text field using the default prefix length settings:
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[source,console]
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--------------------------------
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PUT my-index-000001
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{
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"mappings": {
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"properties": {
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"body_text": {
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"type": "text",
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"index_prefixes": { } <1>
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}
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}
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}
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}
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--------------------------------
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<1> An empty settings object will use the default `min_chars` and `max_chars`
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settings
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This example uses custom prefix length settings:
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[source,console]
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--------------------------------
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PUT my-index-000001
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{
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"mappings": {
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"properties": {
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"full_name": {
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"type": "text",
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"index_prefixes": {
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"min_chars" : 1,
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"max_chars" : 10
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}
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}
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}
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}
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}
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--------------------------------
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`index_prefixes` parameter instructs {ES} to create a subfield "._index_prefix". This
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field will be used to do fast prefix queries. When doing highlighting, add "._index_prefix"
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subfield to the `matched_fields` parameter to highlight the main field based on the
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found matches of the prefix field, like in the request below:
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[source,console]
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--------------------------------
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GET my-index-000001/_search
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{
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"query": {
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"prefix": {
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"full_name": {
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"value": "ki"
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}
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}
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},
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"highlight": {
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"fields": {
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"full_name": {
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"matched_fields": ["full_name._index_prefix"]
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}
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}
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}
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}
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--------------------------------
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// TEST[continued]
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