📅 最后修改于: 2020-10-30 14:22:56 🧑 作者: Mango
它是一个组件，允许针对Elasticsearch实时执行类似SQL的查询。您可以将Elasticsearch SQL视为一种翻译器，可以理解SQL和Elasticsearch，并可以利用Elasticsearch功能轻松地进行大规模实时读取和处理数据。
它具有本机集成-根据底层存储，对相关节点高效地执行每个查询。
无需外部零件-无需额外的硬件，流程，运行时或库即可查询Elasticsearch。
轻巧高效-它包含并公开了SQL，可以实时进行适当的全文本搜索。
PUT /schoollist/_bulk?refresh
{"index":{"_id": "CBSE"}}
{"name": "GleanDale", "Address": "JR. Court Lane", "start_date": "2011-06-02",
"student_count": 561}
{"index":{"_id": "ICSE"}}
{"name": "Top-Notch", "Address": "Gachibowli Main Road", "start_date": "1989-
05-26", "student_count": 482}
{"index":{"_id": "State Board"}}
{"name": "Sunshine", "Address": "Main Street", "start_date": "1965-06-01",
"student_count": 604}
运行上面的代码后，我们得到如下所示的响应：
{
"took" : 277,
"errors" : false,
"items" : [
{
"index" : {
"_index" : "schoollist",
"_type" : "_doc",
"_id" : "CBSE",
"_version" : 1,
"result" : "created",
"forced_refresh" : true,
"_shards" : {
"total" : 2,
"successful" : 1,
"failed" : 0
},
"_seq_no" : 0,
"_primary_term" : 1,
"status" : 201
}
},
{
"index" : {
"_index" : "schoollist",
"_type" : "_doc",
"_id" : "ICSE",
"_version" : 1,
"result" : "created",
"forced_refresh" : true,
"_shards" : {
"total" : 2,
"successful" : 1,
"failed" : 0
},
"_seq_no" : 1,
"_primary_term" : 1,
"status" : 201
}
},
{
"index" : {
"_index" : "schoollist",
"_type" : "_doc",
"_id" : "State Board",
"_version" : 1,
"result" : "created",
"forced_refresh" : true,
"_shards" : {
"total" : 2,
"successful" : 1,
"failed" : 0
},
"_seq_no" : 2,
"_primary_term" : 1,
"status" : 201
}
}
]
}
以下示例显示了如何构建SQL查询-
POST /_sql?format=txt
{
"query": "SELECT * FROM schoollist WHERE start_date < '2000-01-01'"
}
运行上面的代码后，我们得到如下所示的响应：
Address | name | start_date | student_count
--------------------+---------------+------------------------+---------------
Gachibowli Main Road|Top-Notch |1989-05-26T00:00:00.000Z|482
Main Street |Sunshine |1965-06-01T00:00:00.000Z|604
注意-通过更改上面的SQL查询，您可以获得不同的结果集。