code: func (c *Client) IsRequestTypeSupported(reqType, subType int64) bool {
  	switch reqType {
  	case kv.ReqTypeSelect, kv.ReqTypeIndex:
  		switch subType {
  		case kv.ReqSubTypeGroupBy, kv.ReqSubTypeBasic, kv.ReqSubTypeTopN:
  			return true
  		default:
  			return c.supportExpr(tipb.ExprType(subType))
  		}
  	case kv.ReqTypeDAG:
  		return c.supportExpr(tipb.ExprType(subType))
  	case kv.ReqTypeAnalyze:
  		return true
  	}
  	return false
  }
docs: // IsRequestTypeSupported implement kv.Client interface.