@Override public void prepareRun(BatchJoinerContext context) throws Exception { if (conf.getNumPartitions() != null) { context.setNumPartitions(conf.getNumPartitions()); } init(context.getInputSchemas()); Collection<OutputFieldInfo> outputFieldInfos = createOutputFieldInfos(context.getInputSchemas()); context.record(createFieldOperations(outputFieldInfos, perStageJoinKeys)); }