ES08# ElasticSearch中的SQL查询
引言
通过SQL进行检索ElasticSearch的文档，在一些复杂场景更为灵活。由于DSL需要熟悉其语法，自建的日志平台可能将DSL屏蔽和封装，暴露SQL的查询更易上手。本文顺着官方指南实操一把，文章内容有。
Kibana执行SQL查询
Post请求执行SQL分页查询
SQL中使用DSL过滤
使用复杂查询条件
其他查询方式（运行时字段与异步SQL）
一、Kibana执行SQL查询
请求示例：
POST /_sql?format=txt
{
"query": """
SELECT "pid","span_id","trace_id","user_id" FROM "prd_detail-xxx_*" LIMIT 10
"""
}返回结果：
pid | span_id | trace_id | user_id
---------------+----------------+----------------+---------------
833037 |a481fcd11b5e7ef3|0ffc42e668901b86|null
2631155 |44273ff566fc9634|2a770bf4a65425e6|null
1397839 |691f7a77caf21a4c|ebc60684c13a2af3|null
3984591 |638c9eda5973bcd3|e36218668bcac321|null备注：在使用kibana console会使用三引号(""")，format格式支持csv、json、txt、yaml等众多格式，查询支持*号。
二、Post请求执行SQL分页查询
1.添加测试数据
先造点测试数据，方便测试，请求URL：
PUT /library/_bulk?refresh输入参数：
{"index":{"_id": "Leviathan Wakes"}}
{"name": "Leviathan Wakes", "author": "James S.A. Corey", "release_date": "2011-06-02", "page_count": 561}
{"index":{"_id": "Hyperion"}}
{"name": "Hyperion", "author": "Dan Simmons", "release_date": "1989-05-26", "page_count": 482}
{"index":{"_id": "Dune"}}
{"name": "Dune", "author": "Frank Herbert", "release_date": "1965-06-01", "page_count": 604}备注：上面命令通过kibana将结果注入。
2.查询数据
请求URL：
http://127.0.0.1:9200/_sql?format=json输入参数：
{
"query": "SELECT * FROM library ORDER BY page_count DESC"
}返回结果：
{
"columns": [
{
"name": "author",
"type": "text"
},
{
"name": "name",
"type": "text"
},
{
"name": "page_count",
"type": "long"
},
{
"name": "release_date",
"type": "datetime"
}
],
"rows": [
[
"Frank Herbert",
"Dune",
604,
"1965-06-01T00:00:00.000Z"
],
[
"James S.A. Corey",
"Leviathan Wakes",
561,
"2011-06-02T00:00:00.000Z"
],
[
"Dan Simmons",
"Hyperion",
482,
"1989-05-26T00:00:00.000Z"
]
]
}备注：Postman中通过SQL查询导入的共计3条数据。
2.分页首次查询
输入参数：
{
"query": "SELECT * FROM library ORDER BY page_count DESC",
"fetch_size": 2
}返回结果：
{
"columns": [
{
"name": "author",
"type": "text"
},
{
"name": "name",
"type": "text"
},
{
"name": "page_count",
"type": "long"
},
{
"name": "release_date",
"type": "datetime"
}
],
"rows": [
[
"Frank Herbert",
"Dune",
604,
"1965-06-01T00:00:00.000Z"
],
[
"James S.A. Corey",
"Leviathan Wakes",
561,
"2011-06-02T00:00:00.000Z"
]
],
"cursor": "i6+xAwFaAXN4RkdsdVkyeDFaR1ZmWTI5dWRHVjRkRjkxZFdsa0RYRjFaWEo1UVc1a1JtVjBZMmdCRm1kbFJGRTBZa2wzVkdwdGN6ZG1RMVo1WlZWSFgyY0FBQUFBQUFBQ0R4WXRNMnhRTm5CTk9GTkljVEV0ZFd4d1IxRjVZbGRS/w8EAWYGYXV0aG9yAQZhdXRob3IBBHRleHQAAAABZgRuYW1lAQRuYW1lAQR0ZXh0AAAAAWYKcGFnZV9jb3VudAEKcGFnZV9jb3VudAEEbG9uZwAAAAFmDHJlbGVhc2VfZGF0ZQEMcmVsZWFzZV9kYXRlAQhkYXRldGltZQEAAAEP"
}备注：Postman中执行，总共3条数据，查询一页2条，返回的最后一行cursor，下一页用它来查。
3.分页第二次查询
输入参数：
{
"cursor": "i6+xAwFaAXN4RkdsdVkyeDFaR1ZmWTI5dWRHVjRkRjkxZFdsa0RYRjFaWEo1UVc1a1JtVjBZMmdCRm5WSmRrWktRM0pIVVhOeGVFNTRVRGsyVFhGNFdIY0FBQUFBQUFBQ2xCWTJTRU5VTUhSTVVGRTNkVXR2U2xCdVdWQnNUekZC/w8EAWYGYXV0aG9yAQZhdXRob3IBBHRleHQAAAABZgRuYW1lAQRuYW1lAQR0ZXh0AAAAAWYKcGFnZV9jb3VudAEKcGFnZV9jb3VudAEEbG9uZwAAAAFmDHJlbGVhc2VfZGF0ZQEMcmVsZWFzZV9kYXRlAQhkYXRldGltZQEAAAEP"
}返回结果：
{
"rows": [
[
"Dan Simmons",
"Hyperion",
482,
"1989-05-26T00:00:00.000Z"
]
],
"cursor": "i6+xAwFaAXN4RkdsdVkyeDFaR1ZmWTI5dWRHVjRkRjkxZFdsa0RYRjFaWEo1UVc1a1JtVjBZMmdCRm5WSmRrWktRM0pIVVhOeGVFNTRVRGsyVFhGNFdIY0FBQUFBQUFBQ2xCWTJTRU5VTUhSTVVGRTNkVXR2U2xCdVdWQnNUekZC/w8EAWYGYXV0aG9yAQZhdXRob3IBBHRleHQAAAABZgRuYW1lAQRuYW1lAQR0ZXh0AAAAAWYKcGFnZV9jb3VudAEKcGFnZV9jb3VudAEEbG9uZwAAAAFmDHJlbGVhc2VfZGF0ZQEMcmVsZWFzZV9kYXRlAQhkYXRldGltZQEAAAEP"
}备注：当继续分页查询时，需要使用上次查询返回的cursor来查，第二次查询依旧一页2条数据，总共3条，返回了1条数据。
4.分页第三次查询
输入参数：
{
"cursor": "i6+xAwFaAXN4RkdsdVkyeDFaR1ZmWTI5dWRHVjRkRjkxZFdsa0RYRjFaWEo1UVc1a1JtVjBZMmdCRm1kbFJGRTBZa2wzVkdwdGN6ZG1RMVo1WlZWSFgyY0FBQUFBQUFBQ2NSWXRNMnhRTm5CTk9GTkljVEV0ZFd4d1IxRjVZbGRS/w8EAWYGYXV0aG9yAQZhdXRob3IBBHRleHQAAAABZgRuYW1lAQRuYW1lAQR0ZXh0AAAAAWYKcGFnZV9jb3VudAEKcGFnZV9jb3VudAEEbG9uZwAAAAFmDHJlbGVhc2VfZGF0ZQEMcmVsZWFzZV9kYXRlAQhkYXRldGltZQEAAAEP"
}返回结果：
{
"rows": []
}备注：当再次输入cursor查询时，返回记录为空，分页结束。
三、SQL中使用DSL过滤
请求URL：
http://127.0.0.1:9200/_sql?format=json输入参数：
{
"query": "SELECT * FROM library ORDER BY page_count DESC",
"filter": {
"range": {
"page_count": {
"gte" : 400,
"lte" : 500
}
}
},
"fetch_size": 2
}返回结果：
{
"columns": [
{
"name": "author",
"type": "text"
},
{
"name": "name",
"type": "text"
},
{
"name": "page_count",
"type": "long"
},
{
"name": "release_date",
"type": "datetime"
}
],
"rows": [
[
"Dan Simmons",
"Hyperion",
482,
"1989-05-26T00:00:00.000Z"
]
]
}备注：可以通过ElasticSearch DSL来过滤结果。
四、柱状显示查询结果
请求参数：
http://127.0.0.1:9200/_sql?format=json输入参数：
{
"query": "SELECT * FROM library ORDER BY page_count DESC",
"fetch_size": 2,
"columnar": true
}返回结果：
{
"columns": [
{
"name": "author",
"type": "text"
},
{
"name": "name",
"type": "text"
},
{
"name": "page_count",
"type": "long"
},
{
"name": "release_date",
"type": "datetime"
}
],
"values": [
[
"Frank Herbert",
"James S.A. Corey"
],
[
"Dune",
"Leviathan Wakes"
],
[
604,
561
],
[
"1965-06-01T00:00:00.000Z",
"2011-06-02T00:00:00.000Z"
]
],
"cursor": "i6+xAwFaAXN4RkdsdVkyeDFaR1ZmWTI5dWRHVjRkRjkxZFdsa0RYRjFaWEo1UVc1a1JtVjBZMmdCRm1kbFJGRTBZa2wzVkdwdGN6ZG1RMVo1WlZWSFgyY0FBQUFBQUFBZkdoWXRNMnhRTm5CTk9GTkljVEV0ZFd4d1IxRjVZbGRS/w8EAWYGYXV0aG9yAQZhdXRob3IBBHRleHQAAAABZgRuYW1lAQRuYW1lAQR0ZXh0AAAAAWYKcGFnZV9jb3VudAEKcGFnZV9jb3VudAEEbG9uZwAAAAFmDHJlbGVhc2VfZGF0ZQEMcmVsZWFzZV9kYXRlAQhkYXRldGltZQEAAAEP"
}备注：通过参数columnar来设置显示样式，默认为false。
五、使用复杂查询条件
请求url：
http://127.0.0.1:9200/_sql?format=json输入参数：
{
"query": "SELECT YEAR(release_date) AS year FROM library WHERE page_count > 300 AND author = 'Frank Herbert' GROUP BY year HAVING COUNT(*) > 0"
}返回结果：
{
"columns": [
{
"name": "year",
"type": "integer"
}
],
"rows": [
[
1965
]
],
"cursor": "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"
}备注：可通过SQL92查询、分组等复杂条件来执行。
六、其他查询方式
可利用运行时字段(runtime fields)对查询结果聚合，过滤和排序，需要es 7.11版本以上，本文使用7.10 不再演示
通常使用同步SQL查询，elasticsearch也支持异步SQL查询