[jira] [Updated] (CALCITE-4964) Reduce recursion when push predicate into CASE

["Ziwei Liu (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-4964?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ziwei Liu updated CALCITE-4964:
-------------------------------
    Summary: Reduce recursion when push predicate into CASE  (was: reduce recursion when push predicate into case)

> 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
>
> I think CaseShuttle do not need a loop of for(;; ).When a predicate is pushed into case, we only need to check the new RexCall whether need to push predicate into the child operand, not need to do a new recursion.
> So I think CaseShuttle 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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