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https://issues.apache.org/jira/browse/CALCITE-2223?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16996509#comment-16996509
 ] 

Vladimir Sitnikov commented on CALCITE-2223:
--------------------------------------------

[~volodymyr], it might be simpler than you think, so you might want to discuss 
it. Drill build files are not much more complicated than the ones from Calcite, 
and the migration might be beneficial for both projects.

Just in case: Calcite migration took a week or so.

> 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: Vova Vysotskyi
>            Priority: Critical
>              Labels: pull-request-available
>         Attachments: 
> TestLimitWithExchanges_testPushLimitPastUnionExchange.png, heap_overview.png, 
> provenance_contents.png
>
>
> 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 (in {{RelOptRulesTest}}):
> {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 greater than ProjectReduceExpressionsRule class name 
> (String.compareTo()).
>    *
>    * 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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