[jira] [Updated] (CALCITE-4578) skip replaceInput when inputs are not changed

["Jiatao Tao (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-4578?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jiatao Tao updated CALCITE-4578:
--------------------------------
    Summary: skip replaceInput when inputs are not changed  (was: skip SetOp#replaceInput when inputs are not changed)

> skip replaceInput when inputs are not changed
> ---------------------------------------------
>
>                 Key: CALCITE-4578
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4578
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>            Reporter: Jiatao Tao
>            Assignee: Jiatao Tao
>            Priority: Major
>         Attachments: image-2021-04-11-17-42-38-595.png
>
>
> Example like that: insert xxx VALUES (1, 'one'), (2, 'two'), (3, 'three')...(10000, 'ten thousand');
> It generates a Union node with 10000 inputs, and the performance is poor, here's the profile:
> !image-2021-04-11-17-42-38-595.png|width=1086,height=240!
> We create a program(HepProgram) to do the union merge, in this case, we only have one union, so the rule is not applied, but it will still build the buildFinalPlan:
> {code:java}
> public RelNode findBestExp() {
>   assert root != null;
>   executeProgram(mainProgram);
>   // Get rid of everything except what's in the final plan.
>   collectGarbage();
>   return buildFinalPlan(root);
> }
> {code}
> And the union have large inputs, so the performance is poor(in SetOp#replaceInput, we have to recomputeDigest ), we can skip recomputeDigest if the inputs is not changed:
> {code:java}
> @Override public void replaceInput(int ordinalInParent, RelNode p) {
>   final List<RelNode> newInputs = new ArrayList<>(inputs);
>   newInputs.set(ordinalInParent, p);
>   if (!newInputs.equals(inputs)) {
>     inputs = ImmutableList.copyOf(newInputs);
>     recomputeDigest();
>   }
> }
> {code}
>  



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