如何在 AWS Glue 中指定连接类型？

Question

我正在使用 AWS Glue 连接两个表。默认情况下，它执行 INNER JOIN。我想做一个左外连接。我参考了 AWS Glue 文档，但无法将连接类型传递给 Join.apply() 方法。有没有办法在 AWS Glue 中实现这一点？

## @type: Join
## @args: [keys1 = id, keys2 = "user_id"]
## @return: cUser
## @inputs: [frame1 = cUser0, frame2 = cUserLogins]
#cUser = Join.apply(frame1 = cUser0, frame2 = +, keys1 = "id", keys2 = "user_id", transformation_ctx = "<transformation_ctx>")


## @type: Join
## @args: [keys1 = id, keys2 = user_id]
## @return: datasource0
## @inputs: [frame1 = cUser, frame2 = cKKR]
datasource0 = Join.apply(frame1 = cUser0, frame2 = cKKR, keys1 = "id", keys2 = "user_id", transformation_ctx = "<transformation_ctx>")

## @type: Join
## @args: [keys1 = branch_id, keys2 = user_id]
## @return: datasource1
## @inputs: [frame1 = datasource0, frame2 = cBranch]
datasource1 = Join.apply(frame1 = datasource0, frame2 = cBranch, keys1 = "branch_id", keys2 = "user_id", transformation_ctx = "<transformation_ctx>")

Answer 1

如果您导入 DynamicFrames from awsglue.dynamicframe import DynamicFrame， 然后你可以做

dataSource2 = DynamicFrame.fromDF(datasource0.join(datasource1, (datasource0['user_id'] == datasource1['user_id']), "left"), glueContext, "dataSource2")

Answer 2

目前，AWS Glue 不支持 LEFT 和 RIGHT 联接。但是，我们仍然可以通过将 DynamicFrame 转换为 DataFrame 并使用 join 方法来实现。

这里是例子：

cUser0 = glueContext.create_dynamic_frame.from_catalog(database = "captains", table_name = "cp_txn_winds_karyakarta_users", transformation_ctx = "cUser")

cUser0DF = cUser0.toDF()

cKKR = glueContext.create_dynamic_frame.from_catalog(database = "captains", table_name = "cp_txn_winds_karyakarta_karyakartas", redshift_tmp_dir = args["TempDir"], transformation_ctx = "cKKR")

cKKRDF = cKKR.toDF()

dataSource0 = cUser0DF.join(cKKRDF, cUser0DF.id == cKKRDF.user_id,how='left_outer')