public RelNode convert( RelOptPlanner planner, RelNode rel, RelDistribution toDistribution, boolean allowInfiniteCostConverters) { if (toDistribution == RelDistributions.ANY) { return rel; } // Create a logical sort, then ask the planner to convert its remaining // traits (e.g. convert it to an EnumerableSortRel if rel is enumerable // convention) final Exchange exchange = LogicalExchange.create(rel, toDistribution); RelNode newRel = planner.register(exchange, rel); final RelTraitSet newTraitSet = rel.getTraitSet().replace(toDistribution); if (!newRel.getTraitSet().equals(newTraitSet)) { newRel = planner.changeTraits(newRel, newTraitSet); } return newRel; }