114 lines
2.8 KiB
Plaintext
114 lines
2.8 KiB
Plaintext
[[query-dsl-terms-query]]
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=== Terms Query
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Filters documents that have fields that match any of the provided terms
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(*not analyzed*). For example:
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[source,js]
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--------------------------------------------------
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GET /_search
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{
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"query": {
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"terms" : { "user" : ["kimchy", "elasticsearch"]}
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}
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}
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--------------------------------------------------
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// CONSOLE
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[float]
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[[query-dsl-terms-lookup]]
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===== Terms lookup mechanism
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When it's needed to specify a `terms` filter with a lot of terms it can
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be beneficial to fetch those term values from a document in an index. A
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concrete example would be to filter tweets tweeted by your followers.
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Potentially the amount of user ids specified in the terms filter can be
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a lot. In this scenario it makes sense to use the terms filter's terms
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lookup mechanism.
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The terms lookup mechanism supports the following options:
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[horizontal]
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`index`::
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The index to fetch the term values from.
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`type`::
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The type to fetch the term values from.
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`id`::
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The id of the document to fetch the term values from.
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`path`::
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The field specified as path to fetch the actual values for the
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`terms` filter.
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`routing`::
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A custom routing value to be used when retrieving the
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external terms doc.
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The values for the `terms` filter will be fetched from a field in a
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document with the specified id in the specified type and index.
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Internally a get request is executed to fetch the values from the
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specified path. At the moment for this feature to work the `_source`
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needs to be stored.
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Also, consider using an index with a single shard and fully replicated
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across all nodes if the "reference" terms data is not large. The lookup
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terms filter will prefer to execute the get request on a local node if
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possible, reducing the need for networking.
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[float]
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===== Terms lookup twitter example
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At first we index the information for user with id 2, specifically, its
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followers, then index a tweet from user with id 1. Finally we search on
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all the tweets that match the followers of user 2.
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[source,js]
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--------------------------------------------------
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PUT /users/user/2
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{
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"followers" : ["1", "3"]
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}
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PUT /tweets/tweet/1
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{
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"user" : "1"
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}
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GET /tweets/_search
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{
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"query" : {
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"terms" : {
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"user" : {
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"index" : "users",
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"type" : "user",
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"id" : "2",
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"path" : "followers"
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}
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}
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}
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}
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--------------------------------------------------
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// CONSOLE
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The structure of the external terms document can also include an array of
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inner objects, for example:
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[source,js]
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--------------------------------------------------
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PUT /users/user/2
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{
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"followers" : [
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{
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"id" : "1"
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},
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{
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"id" : "2"
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}
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]
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}
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--------------------------------------------------
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// CONSOLE
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In which case, the lookup path will be `followers.id`.
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