Examples of org.apache.pig.LoadPushDown.pushProjection()

org.apache.pig.LoadPushDown.pushProjection()

Indicate to the loader fields that will be needed. This can be useful for loaders that access data that is stored in a columnar format where indicating columns to be accessed a head of time will save scans. This method will not be invoked by the Pig runtime if all fields are required. So implementations should assume that if this method is not invoked, then all fields from the input are required. If the loader function cannot make use of this information, it is free to ignore it by returning an appropriate Response @param requiredFieldList RequiredFieldList indicating which columns will be needed. @return Indicates which fields will be returned @throws FrontendException


  @Override
  public RequiredFieldResponse pushProjection(
      RequiredFieldList requiredFieldList) throws FrontendException {
    LoadPushDown pushDown = asLoadPushDown( loader );
    return pushDown == null ? null : pushDown.pushProjection( requiredFieldList );
  }


}

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