本文為您介紹如何使用IntervalJoin語句。
背景信息
IntervalJoin語句可以讓兩個流進行JOIN時，左流和右流中每條記錄只關聯另外一條流上滿足定義的時間范圍內的數據，且進行完JOIN后，仍然保留輸入流上的時間列，讓您繼續進行基于Event Time的操作。
語法格式
SELECT column-names
FROM table1 [AS <alias1>]
[INNER | LEFT | RIGHT |FULL ] JOIN table2
ON table1.column-name1 = table2.key-name1 AND TIMEBOUND_EXPRESSION支持INNER JOIN、LEFT JOIN、RIGHT JOIN和FULL JOIN，如果直接使用JOIN，默認為INNER JOIN。
暫不支持SEMI JOIN和ANTI JOIN。
TIMEBOUND_EXPRESSION為左右兩個流時間屬性列上的區間條件表達式，支持以下三種條件表達式：
ltime = rtime
ltime >= rtime AND ltime < rtime + INTERVAL '10' MINUTE
ltime BETWEEN rtime - INTERVAL '10' SECOND AND rtime + INTERVAL '5' SECOND
示例1（基于Event Time）
統計下單后4個小時內的物流信息。
測試數據
訂單表（Orders）
id
productName
orderTime
1
iphone
2020-04-01 10:00:00.0
2
mac
2020-04-01 10:02:00.0
3
huawei
2020-04-01 10:03:00.0
4
pad
2020-04-01 10:05:00.0
物流表（Shipments）
shipId
orderId
status
shiptime
0
1
shipped
2020-04-01 11:00:00.0
1
2
delivered
2020-04-01 17:00:00.0
2
3
shipped
2020-04-01 12:00:00.0
3
4
shipped
2020-04-01 11:30:00.0
測試語句
CREATE TEMPORARY TABLE Orders( id BIGINT, productName VARCHAR, orderTime TIMESTAMP, WATERMARK wk FOR orderTime as withOffset(orderTime, 2000) --為rowtime定義Watermark。 ) WITH ( type='datahub', endpoint='<yourEndpoint>', accessId='<yourAccessID>', accessKey='<yourAccessSecret>', projectName='<yourProjectName>', topic='<yourTopic>', project='<yourProjectName>' ); CREATE TEMPORARY TABLE Shipments( shipId BIGINT, orderId BIGINT, status VARCHAR, shiptime TIMESTAMP, WATERMARK wk FOR shiptime as withOffset(shiptime, 2000) --為rowtime定義Watermark。 ) WITH ( type='datahub', endpoint='<yourEndpoint>', accessId='<yourAccessID>', accessKey='<yourAccessSecret>', projectName='<yourProjectName>', topic='<yourTopic>', project='<yourProjectName>' ); --使用RDS作為結果表。 CREATE TEMPORARY TABLE rds_output( id BIGINT, productName VARCHAR, status VARCHAR ) WITH ( type='rds', url='<yourDatabaseURL>', tableName='<yourDatabaseTablename>', userName='<yourDatabaseUserName>', password='<yourDatabasePassword>' ); INSERT INTO rds_output SELECT id, productName, status FROM Orders AS o JOIN Shipments AS s on o.id = s.orderId AND o.ordertime BETWEEN s.shiptime - INTERVAL '4' HOUR AND s.shiptime;測試結果
id(bigint)
productName(varchar)
status(varchar)
1
iphone
shipped
3
huawei
shipped
4
pad
shipped
示例2（基于Processing Time）
測試數據
datahub_stream1
k1
v1
1
val1
2
val2
3
val3
datahub_stream2
k1
v1
1
val1
2
val2
3
val3
測試語句
CREATE TEMPORARY TABLE datahub_stream1 ( k1 BIGINT, v1 VARCHAR, d AS PROCTIME() ) WITH ( 'connector' = 'datahub', 'subId' = '<yourSubId>', 'endPoint' = '<yourEndPoint>', 'project' = '<yourProjectName>', 'topic' = '<yourTopicName>', 'accessId' = '<yourAccessId>', 'accessKey' = '<yourAccessKey>' ); CREATE TEMPORARY TABLE datahub_stream2 ( k2 BIGINT, v2 VARCHAR, e AS PROCTIME() ) WITH ( 'connector' = 'datahub', 'subId' = '<yourSubId>', 'endPoint' = '<yourEndPoint>', 'project' = '<yourProjectName>', 'topic' = '<yourTopicName>', 'accessId' = '<yourAccessId>', 'accessKey' = '<yourAccessKey>' ); --使用RDS作為結果表。 CREATE TEMPORARY TABLE rds_output( k1 BIGINT, v1 VARCHAR, v2 VARCHAR ) WITH ( 'connector'='rds', 'tableName'='your-table-name', 'userName'='your-user-name', 'password'='your-password', 'url'='your-url' ); INSERT INTO rds_output SELECT k1, v1, v2 FROM datahub_stream1 AS o JOIN datahub_stream2 AS s on o.k1 = s.k2 AND o.d BETWEEN s.e - INTERVAL '4' MINUTE AND s.e;
由于結果取決于兩個流里每條數據進入系統的時間，具有不確定性，因此該示例暫不提供預期結果。