[jira] [Created] (CALCITE-2223) ProjectMergeRule is infinitely matched when is applied after ProjectReduceExpressionsRule

["Volodymyr Vysotskyi (JIRA)" <ji...@apache.org>]

Volodymyr Vysotskyi created CALCITE-2223:
--------------------------------------------

             Summary: ProjectMergeRule is infinitely matched when is applied after ProjectReduceExpressionsRule
                 Key: CALCITE-2223
                 URL: https://issues.apache.org/jira/browse/CALCITE-2223
             Project: Calcite
          Issue Type: Bug
            Reporter: Volodymyr Vysotskyi
            Assignee: Julian Hyde


For queries like this:
{code:sql}
select t1.f from (select cast(f as int) f, f from (select cast(f as int) f from (values('1')) t(f))) as t1
{code}
OOM is thrown when {{ProjectMergeRule}} is applied before applying {{ProjectReduceExpressionsRule}} in VolcanoPlanner.
 A simple test to reproduce this issue:
{code:java}
  @Test public void testOomProjectMergeRule() {
    RelBuilder relBuilder = RelBuilder.create(RelBuilderTest.config().build());
    RelNode relNode = relBuilder
        .values(new String[]{"f"}, "1")
        .project(
            relBuilder.alias(
                relBuilder.cast(relBuilder.field(0), SqlTypeName.INTEGER),
                "f"))
        .project(
            relBuilder.alias(
                relBuilder.cast(relBuilder.field(0), SqlTypeName.INTEGER),
                "f0"),
            relBuilder.alias(relBuilder.field(0), "f"))
        .project(
            relBuilder.alias(relBuilder.field(0), "f"))
        .build();

    RelOptPlanner planner = relNode.getCluster().getPlanner();
    RuleSet ruleSet =
        RuleSets.ofList(
            ReduceExpressionsRule.PROJECT_INSTANCE,
            new ProjectMergeRuleWithLongerName(),
            EnumerableRules.ENUMERABLE_PROJECT_RULE,
            EnumerableRules.ENUMERABLE_VALUES_RULE);
    Program program = Programs.of(ruleSet);

    RelTraitSet toTraits =
        relNode.getCluster().traitSet()
            .replace(0, EnumerableConvention.INSTANCE);

    RelNode output = program.run(planner, relNode, toTraits,
        ImmutableList.<RelOptMaterialization>of(), ImmutableList.<RelOptLattice>of());

    // check for output
  }

  /**
   * ProjectMergeRule inheritor which has
   * class name longer than ProjectReduceExpressionsRule class name.
   *
   * It is needed for RuleQueue.popMatch() method
   * to apply this rule before ProjectReduceExpressionsRule.
   */
  private static class ProjectMergeRuleWithLongerName extends ProjectMergeRule {
    public ProjectMergeRuleWithLongerName() {
      super(true, RelFactories.LOGICAL_BUILDER);
    }
  }
{code}



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