contrib/storage-cassandra/src/main/java/org/apache/drill/exec/store/cassandra/plan/DrillCassandraLimitRule.java

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 * distributed with this work for additional information
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 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.drill.exec.store.cassandra.plan;

import org.apache.calcite.adapter.cassandra.CassandraLimit;
import org.apache.calcite.adapter.cassandra.CassandraRel;
import org.apache.calcite.plan.RelTraitSet;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.convert.ConverterRule;
import org.apache.drill.exec.planner.common.DrillLimitRelBase;
import org.apache.drill.exec.planner.logical.DrillRel;

public class DrillCassandraLimitRule extends ConverterRule {
  public static final DrillCassandraLimitRule INSTANCE = new DrillCassandraLimitRule();

  private DrillCassandraLimitRule() {
    super(Config.INSTANCE
      .withConversion(DrillLimitRelBase.class, DrillRel.DRILL_LOGICAL,
        CassandraRel.CONVENTION, "DrillCassandraLimitRule"));
  }

  public RelNode convert(RelNode relNode) {
    DrillLimitRelBase limit = (DrillLimitRelBase) relNode;
    final RelTraitSet traitSet =
        limit.getTraitSet().replace(CassandraRel.CONVENTION);
    return new CassandraLimit(limit.getCluster(), traitSet,
        convert(limit.getInput(), CassandraRel.CONVENTION), limit.getOffset(), limit.getFetch());
  }
}