92 lines
3.6 KiB
Plaintext
92 lines
3.6 KiB
Plaintext
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[[breaking_50_suggester]]
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=== Suggester changes
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The completion suggester has undergone a complete rewrite. This means that the
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syntax and data structure for fields of type `completion` have changed, as
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have the syntax and response of completion suggester requests.
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For indices created before Elasticsearch 5.0.0, `completion` fields and the
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completion suggester will continue to work as they did in Elasticsearch 2.x.
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However, it is not possible to run a completion suggester query across indices
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created in 2.x and indices created in 5.x.
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It is strongly recommended to reindex indices containing 2.x `completion`
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fields in 5.x to take advantage of the new features listed below.
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NOTE: You will need to change the structure of the completion field values
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when reindexing.
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==== Completion suggester is near-real time
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Previously, deleted suggestions could be included in results even
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after refreshing an index. Now, deletions are visible in near-real
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time, i.e. as soon as the index has been refreshed. This applies
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to suggestion entries for both context and completion suggesters.
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==== Completion suggester is document-oriented
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Suggestions are aware of the document they belong to. This enables
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retrieving any field value from the document. This is exposed
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through the query-time `payload` option in `completion` and `context`
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suggesters:
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[source,sh]
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---------------
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GET /my_index/_search
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{
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"suggest": {
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"fooSuggestion": {
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"text": "f"
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"completion": {
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"field": "fooSuggest",
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"payload": ["field1", "field2"]
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}
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}
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}
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}
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---------------
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Previously, `context` and `completion` suggesters supported an index-time
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`payloads` option, which was used to store and return metadata with suggestions.
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Now metadata can be stored as a field in the same document as the
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suggestion for enabling retrieval at query-time. The support for
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index-time `payloads` has been removed to avoid bloating the in-memory
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index with suggestion metadata. The time that it takes to retrieve payloads
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depends heavily on the size of the `_source` field. The smaller the `_source`,
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the faster the retrieval.
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==== Simpler completion indexing
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As suggestions are document-oriented, suggestion metadata (e.g. `output`)
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should now be specified as a field in the document. The support for specifying
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`output` when indexing suggestion entries has been removed. Now suggestion
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result entry's `text` is always the un-analyzed value of the suggestion's
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`input` (same as not specifying `output` while indexing suggestions in pre-5.0
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indices).
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==== Completion mapping with multiple contexts
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The `context` option in `completion` field mapping is now an array to support
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multiple named contexts per completion field. Note that this is sugar for
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indexing same suggestions under different name with different contexts.
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The `default` option for a named `context` has been removed. Now querying with
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no `context` against a context-enabled completion field yields results from all
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indexed suggestions. Note that performance for match-all-context query
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degrades with the number of unique context value for a given `completion` field.
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==== Completion suggestion with multiple context filtering
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Previously `context` option in a suggest request was used for filtering suggestions
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by `context` value. Now, the option has been named to `contexts` to specify
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multiple named context filters. Note that this is not supported by pre-5.0 indices.
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Following is the `contexts` snippet for a suggest query filtered by both 'color'
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and 'location' contexts:
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[source,sh]
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---------------
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"contexts": {
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"color": [ {...} ],
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"location": [ {...} ]
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}
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---------------
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