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3b96055b23
By default the number of searches msearch executes is capped by the number of nodes multiplied with the default size of the search threadpool. This default can be overwritten by using the newly added `max_concurrent_searches` parameter. Before the msearch api would concurrently execute all searches concurrently. If many large msearch requests would be executed this could lead to some searches being rejected while other searches in the msearch request would succeed. The goal of this change is to avoid this exhausting of the search TP. Closes #17926
83 lines
2.8 KiB
Plaintext
83 lines
2.8 KiB
Plaintext
[[search-multi-search]]
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== Multi Search API
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The multi search API allows to execute several search requests within
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the same API. The endpoint for it is `_msearch`.
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The format of the request is similar to the bulk API format, and the
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structure is as follows (the structure is specifically optimized to
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reduce parsing if a specific search ends up redirected to another node):
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[source,js]
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--------------------------------------------------
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header\n
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body\n
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header\n
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body\n
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--------------------------------------------------
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The header part includes which index / indices to search on, optional
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(mapping) types to search on, the `search_type`, `preference`, and
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`routing`. The body includes the typical search body request (including
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the `query`, `aggregations`, `from`, `size`, and so on). Here is an example:
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[source,js]
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--------------------------------------------------
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$ cat requests
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{"index" : "test"}
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{"query" : {"match_all" : {}}, "from" : 0, "size" : 10}
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{"index" : "test", "search_type" : "dfs_query_then_fetch"}
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{"query" : {"match_all" : {}}}
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{}
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{"query" : {"match_all" : {}}}
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{"query" : {"match_all" : {}}}
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{"search_type" : "dfs_query_then_fetch"}
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{"query" : {"match_all" : {}}}
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$ curl -XGET localhost:9200/_msearch --data-binary "@requests"; echo
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--------------------------------------------------
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Note, the above includes an example of an empty header (can also be just
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without any content) which is supported as well.
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The response returns a `responses` array, which includes the search
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response for each search request matching its order in the original
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multi search request. If there was a complete failure for that specific
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search request, an object with `error` message will be returned in place
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of the actual search response.
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The endpoint allows to also search against an index/indices and
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type/types in the URI itself, in which case it will be used as the
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default unless explicitly defined otherwise in the header. For example:
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[source,js]
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--------------------------------------------------
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$ cat requests
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{}
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{"query" : {"match_all" : {}}, "from" : 0, "size" : 10}
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{}
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{"query" : {"match_all" : {}}}
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{"index" : "test2"}
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{"query" : {"match_all" : {}}}
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$ curl -XGET localhost:9200/test/_msearch --data-binary @requests; echo
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--------------------------------------------------
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The above will execute the search against the `test` index for all the
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requests that don't define an index, and the last one will be executed
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against the `test2` index.
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The `search_type` can be set in a similar manner to globally apply to
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all search requests.
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The msearch's `max_concurrent_searches` request parameter can be used to control
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the maximum number of concurrent searches the multi search api will execute.
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This default is based on the number of data nodes and the default search thread pool size.
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[float]
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[[msearch-security]]
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=== Security
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See <<url-access-control>>
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