Elasticsearch mget
----multi-get----
Elasticsearch 的速度已经很快了，但甚至能更快。 来将这些检索请求放在一个请求中，将比逐个文档请求更快地检索到全部文档。
mget API 要求有一个 docs 数组作为参数，每个_source 参数来指定这些字段的名字：
GET /_mget
{
"docs" : [
{
"_index" : "website",
"_type" : "blog",
"_id" : 2
},
{
"_index" : "website",
"_type" : "pageviews",
"_id" : 1,
"_source": "views"
}
]
}
该响应体也包含一个 docs 数组get request 请求所得到的响应体相同：
{
"docs": [
{
"_index": "website",
"_type": "blog",
"_id": "2",
"_version": 6,
"found": true,
"_source": {
"title": "My first external blog entry",
"text": "Starting "
}
},
{
"_index": "website",
"_type": "pageviews",
"_id": "1",
"_version": 5,
"found": true,
"_source": {
"views": 5
}
}
]
}
如果检索的数据都在相同的_index（甚至相同的_type）中，则可以在URL中指定默认的/_index或者默认的/_index/_type，也可以通过单独的请求覆盖这些值：
GET /website/blog/_mget
{
"docs" : [
{ "_id" : 2 },
{ "_type" : "pageviews", "_id" : 1 }
]
}
{ "docs": [ { "_index": "website", "_type": "blog", "_id": "2", "_version": 6, "found": true, "_source": { "title": "My first external blog entry", "text": "Starting " } }, { "_index": "website", "_type": "pageviews", "_id": "1", "_version": 5, "found": true, "_source": { "views": 5 } } ] }
事实上如果所有文档的_index和_type都是相同的，你可以只传一个ids数组，而不是整个docs数组：
GET /website/blog/_mget
{
"ids" : [ "2", "1" ,"30"]
}
这里的id为1,2 的文档是存在的，30文档是不存在的。并不会影响其他文档的检索，每个文档都是单独索引和报告的
{ "docs": [ { "_index": "website", "_type": "blog", "_id": "2", "_version": 6, "found": true, "_source": { "title": "My first external blog entry", "text": "Starting " } }, { "_index": "website", "_type": "blog", "_id": "1", "_version": 4, "found": true, "_source": { "title": "My first blog entry", "text": "Starting to get the hang of this...", "views": 1, "tags": [ "testing" ] } }, { "_index": "website", "_type": "blog", "_id": "30", "found": false } ] }