public static SamzaSqlRelRecord getMessageKeyRelRecord(SamzaSqlRelMessage message, List<Integer> streamFieldIds,
      List<String> tableFieldNames, List<Integer> tableKeyIds) {
    return createSamzaSqlCompositeKey(message, streamFieldIds,
        getSamzaSqlCompositeKeyFieldNames(tableFieldNames, tableKeyIds));
  }
This abstract class joins incoming {@link SamzaSqlRelMessage} with records from a table with the join key.
samza-sql/src/main/java/org/apache/samza/sql/translator/SamzaSqlTableJoinFunction.java