[jira] [Comment Edited] (CALCITE-2582) FilterProjectTransposeRule does not always simplify the new filter condition

["Vladimir Sitnikov (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-2582?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16623397#comment-16623397 ] 

Vladimir Sitnikov edited comment on CALCITE-2582 at 9/21/18 10:42 AM:
----------------------------------------------------------------------

Alternative option is to use the following approach:
{code:java}    RelNode newFilterRel =
        relBuilder.push(project.getInput()).filter(newCondition).build();

    if (newFilterRel instanceof Filter && copyFilter
        && filter.getClass() != newFilterRel.getClass()) {
      Filter x = (Filter) newFilterRel;
      newFilterRel = filter.copy(filter.getTraitSet(), x.getInput(), x.getCondition());
    }

    RelNode newProjRel =
        relBuilder.push(newFilterRel)
            .project(project.getProjects(), project.getRowType().getFieldNames())
            .build();
    if (newProjRel instanceof Project && copyProject
        && project.getClass() != newProjRel.getClass()) {
      Project x = (Project) newProjRel;
      newProjRel =
          project.copy(project.getTraitSet(), x.getInput(), x.getProjects(), x.getRowType());
    }
{code}

The good part with that approach is encapsulates all the smarts into RelBuilder.

[~julianhyde], [~zabetak] what do you think?


was (Author: vladimirsitnikov):
Alternative option is to use the following approach:
{code:java}    final RelBuilder relBuilder = call.builder();
    RelNode newFilterRel =
        relBuilder.push(project.getInput()).filter(newCondition).build();

    if (newFilterRel instanceof Filter && copyFilter) {
      Filter x = (Filter) newFilterRel;
      newFilterRel = filter.copy(filter.getTraitSet(), x.getInput(), x.getCondition());
    }

    RelNode newProjRel =
        relBuilder.push(newFilterRel)
            .project(project.getProjects(), project.getRowType().getFieldNames())
            .build();
    if (newProjRel instanceof Project && copyProject) {
      Project x = (Project) newProjRel;
      newProjRel =
          project.copy(project.getTraitSet(), x.getInput(), x.getProjects(), x.getRowType());
    }

    call.transformTo(newProjRel);
{code}

The good part with that approach is encapsulates all the smarts into RelBuilder.

[~julianhyde], [~zabetak] what do you think?

> FilterProjectTransposeRule does not always simplify the new filter condition
> ----------------------------------------------------------------------------
>
>                 Key: CALCITE-2582
>                 URL: https://issues.apache.org/jira/browse/CALCITE-2582
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 1.17.0
>            Reporter: Stamatis Zampetakis
>            Assignee: Julian Hyde
>            Priority: Minor
>             Fix For: 1.18.0
>
>
> After pushing the filter below the project a new condition is going to be generated along with a new Filter operator. The new condition is not going to be simplified if the filter operator is copied and not created using the RelBuilder. 
> Thus the resulting plan may contain redundant conditions which can have a slight impact on performance. Apart, from that tests verifying the resulting (logical/physical) plan may produce indeterministic results if the rule is applied with (a different order and in combination with other rules). 



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