[CP] Fix the problem of still performing hard parsing when the SQL current limit reaches 0

src/sql/engine/ob_physical_plan.cpp

@@ -692,7 +692,9 @@ int ObPhysicalPlan::inc_concurrent_num()
   } else {
     while(OB_SUCC(ret) && false == is_succ) {
       concurrent_num = ATOMIC_LOAD(&concurrent_num_);
-      if (concurrent_num >= max_concurrent_num_) {
+      if (0 == max_concurrent_num_) {
+        ret = OB_REACH_MAX_CONCURRENT_NUM;
+      } else if (concurrent_num >= max_concurrent_num_) {
         ret = OB_REACH_MAX_CONCURRENT_NUM;
       } else {
         new_num = concurrent_num + 1;

src/sql/ob_sql.cpp

@@ -4329,6 +4329,9 @@ int ObSql::pc_add_plan(ObPlanCacheCtx &pc_ctx,
       ret = plan_cache->add_plan(phy_plan, pc_ctx);
     }
     plan_added = (OB_SUCCESS == ret);
+    if (pc_ctx.is_max_curr_limit_) {
+      ret = OB_REACH_MAX_CONCURRENT_NUM;
+    }
 
     if (is_batch_exec) {
       // Batch optimization cannot continue for errors other than OB_SQL_PC_PLAN_DUPLICATE.

src/sql/plan_cache/ob_plan_cache_struct.h

@@ -386,7 +386,8 @@ struct ObPlanCacheCtx : public ObILibCacheCtx
       dynamic_param_info_list_(allocator),
       tpl_sql_const_cons_(allocator),
       need_retry_add_plan_(true),
-      insert_batch_opt_info_(allocator)
+      insert_batch_opt_info_(allocator),
+      is_max_curr_limit_(false)
   {
     fp_result_.pc_key_.mode_ = mode_;
   }
@@ -459,7 +460,8 @@ struct ObPlanCacheCtx : public ObILibCacheCtx
     K(is_original_ps_mode_),
     K(new_raw_sql_),
     K(need_retry_add_plan_),
-    K(insert_batch_opt_info_)
+    K(insert_batch_opt_info_),
+    K(is_max_curr_limit_)
     );
   PlanCacheMode mode_; //control use which variables to do match
 
@@ -521,6 +523,7 @@ struct ObPlanCacheCtx : public ObILibCacheCtx
   // when schema version of cache node is old, whether remove this node and retry add cache obj.
   bool need_retry_add_plan_;
   ObInsertBatchOptInfo insert_batch_opt_info_;
+  bool is_max_curr_limit_;
 };
 
 struct ObPlanCacheStat

src/sql/plan_cache/ob_plan_set.cpp

@@ -1206,7 +1206,18 @@ int ObSqlPlanSet::add_plan(ObPhysicalPlan &plan,
                                        candi_table_locs))) {
     LOG_WARN("fail to get physical locations", K(ret));
   } else if (OB_FAIL(set_concurrent_degree(outline_param_idx, plan))) {
+    if (OB_REACH_MAX_CONCURRENT_NUM == ret && 0 == plan.get_max_concurrent_num()) {
+      pc_ctx.is_max_curr_limit_ = true;
+      ret = OB_SUCCESS;
+    } else {
       LOG_WARN("fail to check concurrent degree", K(ret));
+    }
+  } else {
+    // do nothing
+  }
+
+  if (OB_FAIL(ret)) {
+    // do nothing
   } else {
     if (pc_ctx.exec_ctx_.get_physical_plan_ctx()->get_or_expand_transformed()) {
       need_try_plan_ |= TRY_PLAN_OR_EXPAND;
@@ -1308,7 +1319,6 @@ int ObSqlPlanSet::add_plan(ObPhysicalPlan &plan,
    //   }
    // }
   }
-
   return ret;
 }