[jira] [Commented] (CALCITE-4964) reduce recursion when push predicate into case

["Stamatis Zampetakis (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-4964?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17465004#comment-17465004 ] 

Stamatis Zampetakis commented on CALCITE-4964:
----------------------------------------------

Thanks for submitting this case [~Ziwei Liu] . It is not clear what this Jira is about.

Is it a performance improvement? Is it a bug fix? Is it refactoring for readability?

Please upgrade the description to better reflect the purpose of the change.

 

> reduce recursion when push predicate into case
> ----------------------------------------------
>
>                 Key: CALCITE-4964
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4964
>             Project: Calcite
>          Issue Type: Improvement
>            Reporter: Ziwei Liu
>            Assignee: Ziwei Liu
>            Priority: Major
>
> CaseShuttle's recursion can be reduced like:
> {code:java}
> @Override public RexNode visitCall(RexCall call) {
>    call = (RexCall) super.visitCall(call);
>    if (call instanceof OdpsLambdaRexCall) {
>       return call;
>    }
>    final RexCall old = call;
>    call = ReduceExpressionsRule.pushPredicateIntoCase(call);
>    if (call == old) {
>      return call;
>    } else {
>       boolean containCase = false;
>       List<RexNode> newOps = new ArrayList<>(call.getOperands().size());
>       // call will be like case when c1 then f(x1 ...)
>       // check whether need push f into x1
>       for (int i = 0; i < call.getOperands().size(); i ++) {
>          RexNode op = call.getOperands().get(i);
>          RexNode newOp = op;
>          if (i % 2 == 1 || i == call.getOperands().size() - 1) {
>            if (op instanceof RexCall) {
>              newOp = ReduceExpressionsRule.pushPredicateIntoCase((RexCall) op);
>            }
>          }
>          if (op != newOp) {
>            containCase = true;
>          }
>          newOps.add(newOp);
>        }
>        if (!containCase) {
>          return call;
>        } else {
>          return call.clone(call.getType(), newOps);
>        }
>    }    
> } {code}



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