@Override
      public RelNode visit(LogicalFilter filter) {
        RelNode node = visitChild(filter, 0, filter.getInput());
        String logicalOpId = String.format(TranslatorConstants.LOGOPID_TEMPLATE, queryId, "filter", opId++);
        new FilterTranslator(queryId).translate(filter, logicalOpId, translatorContext);
        return node;
      }
Translate Calcite plan to Samza stream operators.
@param relRoot Calcite plan in the form of {@link RelRoot}. RelRoot should not include the sink ({@link TableModify})
@param outputSystemStream Sink associated with the Calcite plan.
@param translatorContext Context maintained across translations.
@param queryId query index of the sql statement corresponding to the Calcite plan in multi SQL statement scenario
               starting with index 0.
samza-sql/src/main/java/org/apache/samza/sql/translator/QueryTranslator.java