@Override
    public void init(Context context) {
      TranslatorContext translatorContext =
          ((SamzaSqlApplicationContext) context.getApplicationTaskContext()).getTranslatorContexts().get(queryId);
      this.msgConverter = translatorContext.getMsgConverter(streamName);
      ContainerContext containerContext = context.getContainerContext();
      metricsRegistry = containerContext.getContainerMetricsRegistry();
      processingTime = new SamzaHistogram(metricsRegistry, logicalOpId, TranslatorConstants.PROCESSING_TIME_NAME);
      queryInputEvents = metricsRegistry.newCounter(queryLogicalId, TranslatorConstants.INPUT_EVENTS_NAME);
      queryInputEvents.clear();
    }
ScanMapFUnction implements MapFunction to process input SamzaSqlRelMessages into output
SamzaSqlRelMessage, performing the table scan
samza-sql/src/main/java/org/apache/samza/sql/translator/ScanTranslator.java