dblink_write implement [FEAT MERGE]

Co-authored-by: zzg19950727 <1071026277@qq.com>
Co-authored-by: xianyu-w <707512433@qq.com>

src/sql/optimizer/ob_explain_log_plan.h

@@ -25,7 +25,8 @@ namespace sql
       : ObLogPlan(ctx, explain_stmt)
     {}
     virtual ~ObExplainLogPlan() {}
-    virtual int generate_raw_plan() override;
+  protected:
+    virtual int generate_normal_raw_plan() override;
   private:
     DISALLOW_COPY_AND_ASSIGN(ObExplainLogPlan);
   };