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elasticsearch查询opendistrosql支持的操作
ElasticSearch 2020-04-21 22:31:54基本操作
要使用该功能，需要将请求发送到_opendistro/_sqlURI。您可以使用请求参数或请求正文（推荐）。
GET https://: /_opendistro/_sql?sql=select * from my-index limit 50
POST https://: /_opendistro/_sql { "query": "SELECT * FROM my-index LIMIT 50" }
您还可以使用curl命令：
curl -XPOST https://localhost:9200/_opendistro/_sql -u username:password -k -d '{"query": "SELECT * FROM kibana_sample_data_flights LIMIT 10"}' -H 'Content-Type: application/json'默认情况下，查询返回JSON，但您也可以选择CSV格式返回数据，需要对format参数进行设置：
POST _opendistro/_sql?format=csv
{
"query": "SELECT * FROM my-index LIMIT 50"
}CSV格式返回数据时，每行对应一个文档，每列对应一个字段。
支持操作
我们支持的SQL操作包括声明、条件、聚合函数、Include和Exclude、常用函数、连接join和展示等操作。
声明statements
表1 声明statements Statement
Example
Select
SELECT * FROM my-index
Delete
DELETE FROM my-index WHERE _id=1
Where
SELECT * FROM my-index WHERE ['field']='value'
Order by
SELECT * FROM my-index ORDER BY _id asc
Group by
SELECT * FROM my-index GROUP BY range(age, 20,30,39)
Limit
SELECT * FROM my-index LIMIT 50 (default is 200)
Union
SELECT * FROM my-index1 UNION SELECT * FROM my-index2
Minus
SELECT * FROM my-index1 MINUS SELECT * FROM my-index2
说明： 与任何复杂查询一样，大型UNION和MINUS语句可能会使集群资源紧张甚至崩溃。
条件Conditions
表2 条件Conditions Condition
Example
Like
SELECT * FROM my-index WHERE name LIKE 'j%'
And
SELECT * FROM my-index WHERE name LIKE 'j%' AND age > 21
Or
SELECT * FROM my-index WHERE name LIKE 'j%' OR age > 21
Count distinct
SELECT count(distinct age) FROM my-index
In
SELECT * FROM my-index WHERE name IN ('alejandro', 'carolina')
Not
SELECT * FROM my-index WHERE name NOT IN ('jane')
Between
SELECT * FROM my-index WHERE age BETWEEN 20 AND 30
Aliases
SELECT avg(age) AS Average_Age FROM my-index
Date
SELECT * FROM my-index WHERE birthday='1990-11-15'
Null
SELECT * FROM my-index WHERE name IS NULL
聚合函数Aggregation
表3 聚合函数Aggregation Aggregation
Example
avg()
SELECT avg(age) FROM my-index
count()
SELECT count(age) FROM my-index
max()
SELECT max(age) AS Highest_Age FROM my-index
min()
SELECT min(age) AS Lowest_Age FROM my-index
sum()
SELECT sum(age) AS Age_Sum FROM my-index
Include和Exclude字段
表4 Include和Exclude Pattern
Example
include()
SELECT include('a*'), exclude('age') FROM my-index
exclude()
SELECT exclude('*name') FROM my-index
函数Functions
表5 函数Functions Function
Example
floor
SELECT floor(number) AS Rounded_Down FROM my-index
trim
SELECT trim(name) FROM my-index
log
SELECT log(number) FROM my-index
log10
SELECT log10(number) FROM my-index
substring
SELECT substring(name, 2,5) FROM my-index
round
SELECT round(number) FROM my-index
sqrt
SELECT sqrt(number) FROM my-index
concat_ws
SELECT concat_ws(' ', age, height) AS combined FROM my-index
/
SELECT number / 100 FROM my-index
%
SELECT number % 100 FROM my-index
date_format
SELECT date_format(date, 'Y') FROM my-index
说明： 必须在文档映射中启用fielddata才能使大多数字符串函数正常工作。
连接操作Joins
表6 连接操作Joins Join
Example
Inner join
SELECT p.firstname, p.lastname, p.gender, dogs.name FROM people p JOIN dogs d ON d.holdersName = p.firstname WHERE p.age > 12 AND d.age > 1
Left outer join
SELECT p.firstname, p.lastname, p.gender, dogs.name FROM people p LEFT JOIN dogs d ON d.holdersName = p.firstname
Cross join
SELECT p.firstname, p.lastname, p.gender, dogs.name FROM people p CROSS JOIN dogs d
相关约束和限制，参考“连接操作Joins”
展示Show
展示show操作与索引模式匹配的索引和映射。您可以使用*或%使用通配符。
表7 展示show Show
Example
Show tables like
SHOW TABLES LIKE logs-*
连接操作Joins
Open Distro for Elasticsearch SQL支持inner joins, left outer joins,和cross joins。Join操作有许多约束：
您只能加入两个参数。
您必须为索引使用别名（例如people p）。
在ON子句中，您只能使用AND条件。
在WHERE语句中，不要将包含多个索引的树组合在一起。例如，以下语句有效：
WHERE (a.type1 > 3 OR a.type1 < 0) AND (b.type2 > 4 OR b.type2 < -1)
以下声明无效：WHERE (a.type1 > 3 OR b.type2 < 0) AND (a.type1 > 4 OR b.type2 < -1)
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