181 lines
7.6 KiB
Plaintext
181 lines
7.6 KiB
Plaintext
[[java-rest-high-search]]
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=== Search API
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[[java-rest-high-document-search-request]]
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==== Search Request
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The `SearchRequest` is used for any operation that has to do with searching
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documents, aggregations, suggestions and also offers ways of requesting
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highlighting on the resulting documents.
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In its most basic form, a query can be added to the request like this:
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["source","java",subs="attributes,callouts,macros"]
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--------------------------------------------------
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include-tagged::{doc-tests}/SearchDocumentationIT.java[search-request-basic]
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--------------------------------------------------
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<1> Creates the `SeachRequest`. Without arguments this runs against all indices.
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<2> Most parameters of the search can be added to the `SearchSourceBuilder`
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which contains everything that
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in the Rest API would be placed in the search request body.
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<3> Add a `match_all` query to the `SearchSourceBuilder`.
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==== Optional arguments
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Lets first look at some of the optional argument of a `SearchRequest`.
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First of all, the request can be restricted to one or more indices using the
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constructor or to on or more types using a setter:
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["source","java",subs="attributes,callouts,macros"]
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--------------------------------------------------
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include-tagged::{doc-tests}/SearchDocumentationIT.java[search-request-indices-types]
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--------------------------------------------------
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There are a couple of other interesting optional parameters:
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["source","java",subs="attributes,callouts,macros"]
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--------------------------------------------------
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include-tagged::{doc-tests}/SearchDocumentationIT.java[search-request-routing]
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--------------------------------------------------
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<1> Set a routing parameter
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["source","java",subs="attributes,callouts,macros"]
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--------------------------------------------------
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include-tagged::{doc-tests}/SearchDocumentationIT.java[search-request-indicesOptions]
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--------------------------------------------------
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<1> Setting `IndicesOptions` controls how unavailable indices are resolved and
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how wildcard expressions are expanded
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["source","java",subs="attributes,callouts,macros"]
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--------------------------------------------------
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include-tagged::{doc-tests}/SearchDocumentationIT.java[search-request-preference]
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--------------------------------------------------
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<1> Use the preference parameter e.g. to execute the search to prefer local
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shards. The The default is to randomize across shards.
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==== Using the SearchSourceBuilder
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Most options controlling the search behavior can be set on the
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`SearchSourceBuilder`,
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which contains more or less the equivalent of the options in the search request
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body of the Rest API.
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Here are a few examples of some common options:
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["source","java",subs="attributes,callouts,macros"]
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--------------------------------------------------
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include-tagged::{doc-tests}/SearchDocumentationIT.java[search-source-basics]
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--------------------------------------------------
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<1> Create a `SearchSourceBuilder` with default options.
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<2> Set the query. Can be any type of `QueryBuilder`
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<3> Set the `from` option that determines the result index to start searching
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from. Defaults to 0.
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<4> Set the `size` option that determines the number of search hits to return.
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Defaults to 10.
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<5> Set an optional timeout that controls how long the search is allowed to
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take.
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After this, the `SearchSourceBuilder` only needs to be added to the
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`SearchRequest`:
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["source","java",subs="attributes,callouts,macros"]
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--------------------------------------------------
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include-tagged::{doc-tests}/SearchDocumentationIT.java[search-source-setter]
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--------------------------------------------------
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[[java-rest-high-document-search-sync]]
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==== Synchronous Execution
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When executing a `SearchRequest` in the following manner, the client waits
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for the `SearchResponse` to be returned before continuing with code execution:
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["source","java",subs="attributes,callouts,macros"]
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--------------------------------------------------
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include-tagged::{doc-tests}/SearchDocumentationIT.java[search-execute]
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--------------------------------------------------
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[[java-rest-high-document-search-async]]
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==== Asynchronous Execution
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Executing a `SearchRequest` can also be done in an asynchronous fashion so that
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the client can return directly. Users need to specify how the response or
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potential failures will be handled by passing in appropriate listeners:
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["source","java",subs="attributes,callouts,macros"]
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--------------------------------------------------
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include-tagged::{doc-tests}/SearchDocumentationIT.java[search-execute-async]
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--------------------------------------------------
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<1> Called when the execution is successfully completed.
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<2> Called when the whole `SearchRequest` fails.
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==== SearchResponse
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The `SearchResponse` that is returned by executing the search provides details
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about the search execution itself as well as access to the documents returned.
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First, there is useful information about the request execution itself, like the
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HTTP status code, execution time or wether the request terminated early or timed
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out:
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["source","java",subs="attributes,callouts,macros"]
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--------------------------------------------------
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include-tagged::{doc-tests}/SearchDocumentationIT.java[search-response-1]
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--------------------------------------------------
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Second, the response also provides information about the execution on the
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shard level by offering statistics about the total number of shards that were
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affected by the search, and the successful vs. unsuccessful shards. Possible
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failures can also be handled by iterating over an array off
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`ShardSearchFailures` like in the following example:
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["source","java",subs="attributes,callouts,macros"]
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--------------------------------------------------
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include-tagged::{doc-tests}/SearchDocumentationIT.java[search-response-2]
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--------------------------------------------------
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To get access to the returned documents, we need to first get the `SearchHits`
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contained in the response:
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["source","java",subs="attributes,callouts,macros"]
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--------------------------------------------------
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include-tagged::{doc-tests}/SearchDocumentationIT.java[search-hits-get]
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--------------------------------------------------
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The `SearchHits` provides global information about all hits, like total number
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of hits or the maximum score:
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["source","java",subs="attributes,callouts,macros"]
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--------------------------------------------------
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include-tagged::{doc-tests}/SearchDocumentationIT.java[search-hits-info]
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--------------------------------------------------
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Nested inside the `SearchHits` are the individual search results that can
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be iterated over like this:
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["source","java",subs="attributes,callouts,macros"]
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--------------------------------------------------
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include-tagged::{doc-tests}/SearchDocumentationIT.java[search-hits-singleHit]
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--------------------------------------------------
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The `SearchHit` provides access to basic information like index, type, docId and
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score of each search hit:
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["source","java",subs="attributes,callouts,macros"]
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--------------------------------------------------
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include-tagged::{doc-tests}/SearchDocumentationIT.java[search-hits-singleHit-properties]
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--------------------------------------------------
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Furthermore, it lets you get back the document source, either as a simple
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JSON-String or as a map of key/value pairs. In this map, regular fields
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are keyed by the field name and contain the field value. Multi-valued fields are
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returned as lists of objects, nested objects as another key/value map. These
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cases need to be case accordingly:
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["source","java",subs="attributes,callouts,macros"]
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--------------------------------------------------
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include-tagged::{doc-tests}/SearchDocumentationIT.java[search-hits-singleHit-source]
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--------------------------------------------------
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