6.3.4 Source filtering 筛选所需的原始数据

默认情况下 Elasticsearch 会把匹配到的结果，它入索引时候的原始数据原样返回出来，这原始数据会通过 _source 字段返回。你也可以通过 fields 参数来控制 Elasticsearch 的这一特性或者通过 _source 参数来禁止 Elasticsearch 返回源数据。

要禁用的话，只要把 _source 设置成 false 即可：

{
    "_source": false,
    "query" : {
        "term" : { "user" : "kimchy" }
    }
}

_source 也支持通配符，你可以通过使用通配符来指明你需要返回源数据的哪部分信息，比如这样：

{
    "_source": "obj.*",
    "query" : {
        "term" : { "user" : "kimchy" }
    }
}

或者这样：

{
    "_source": [ "obj1.*", "obj2.*" ],
    "query" : {
        "term" : { "user" : "kimchy" }
    }
}

最后演示的是，怎么通过 include 和 exclude 来进行更精准地筛选需要返回的源数据

{
    "_source": {
        "include": [ "obj1.*", "obj2.*" ],
        "exclude": [ "*.description" ]
    },
    "query" : {
        "term" : { "user" : "kimchy" }
    }
}

Allows to control how the _source field is returned with every hit.

By default operations return the contents of the _source field unless you have used the fields parameter or if the _source field is disabled.

You can turn off _source retrieval by using the _source parameter:

To disable _source retrieval set to false:

{
    "_source": false,
    "query" : {
        "term" : { "user" : "kimchy" }
    }
}

The _source also accepts one or more wildcard patterns to control what parts of the _source should be returned:

For example:

{
    "_source": "obj.*",
    "query" : {
        "term" : { "user" : "kimchy" }
    }
}

Or

{
    "_source": [ "obj1.*", "obj2.*" ],
    "query" : {
        "term" : { "user" : "kimchy" }
    }
}

Finally, for complete control, you can specify both include and exclude patterns:

{
    "_source": {
        "include": [ "obj1.*", "obj2.*" ],
        "exclude": [ "*.description" ]
    },
    "query" : {
        "term" : { "user" : "kimchy" }
    }
}