io.cdap.cdap.etl.api.join

Interface AutoJoiner

All Known Implementing Classes:

BatchAutoJoiner

@Beta
public interface AutoJoiner

Joins data from two or more input stages together. For example, the following represents a left outer join on 'purchases'.'user_id' = 'users'.'id':

   
     JoinDefinition define(AutoJoinerContext context) {
       JoinStage purchases = JoinStage.builder(context.getInputStages().get("purchases"))
         .isRequired()
         .build();
       JoinStage users = JoinStage.builder(context.getInputStages().get("users"))
         .isOptional()
         .build();

       JoinCondition condition = JoinCondition.onKeys()
         .addKey(new JoinKey("users", Arrays.asList("id")))
         .addKey(new JoinKey("purchases", Arrays.asList("user_id")))
         .build();

       return JoinDefinition.builder()
         // stage name, field name, optional alias
         .select(new Field("purchases", "id", "purchase_id"),
                 new Field("purchases", "user_id"),
                 new Field("users", "email"))
         .from(purchases, users)
         .on(condition)
         .build()
     }
   
 

Method Summary

Modifier and Type	Method and Description
JoinDefinition	define(AutoJoinerContext context)

Method Detail

define

@Nullable
JoinDefinition define(AutoJoinerContext context)

Returns:

definition about what type of join to execute, or null if the definition cannot be created due to macro values not being evaluated yet.