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

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

Ziwei Liu created CALCITE-4964:
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             Summary: 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


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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