From bc26b2f1633665939f9ffce792163b430547e3eb Mon Sep 17 00:00:00 2001
From: obdev <obdev@oceanbase.com>
Date: Thu, 2 Jun 2022 10:10:55 +0800
Subject: [PATCH] [CP] remove const params in window function

---
 src/sql/optimizer/ob_select_log_plan.cpp | 16 +++++++++++
 src/sql/optimizer/ob_select_log_plan.h   |  1 +
 src/sql/resolver/expr/ob_raw_expr.cpp    | 36 ++++++++++++++++++++++++
 src/sql/resolver/expr/ob_raw_expr.h      |  2 +-
 4 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/src/sql/optimizer/ob_select_log_plan.cpp b/src/sql/optimizer/ob_select_log_plan.cpp
index 5cb50e1433..7c4274448a 100644
--- a/src/sql/optimizer/ob_select_log_plan.cpp
+++ b/src/sql/optimizer/ob_select_log_plan.cpp
@@ -1719,6 +1719,20 @@ int ObSelectLogPlan::decide_sort_keys_for_runion(
   return ret;
 }
 
+int ObSelectLogPlan::remove_const_in_window_functions(ObIArray<ObWinFunRawExpr *> &win_funcs)
+{
+  int ret = OB_SUCCESS;
+  for (int64_t i = 0; OB_SUCC(ret) && i < win_funcs.count(); ++i) {
+    if (OB_ISNULL(win_funcs.at(i))) {
+      ret = OB_ERR_UNEXPECTED;
+      LOG_WARN("get unexpected null", K(ret));
+    } else if (OB_FAIL(win_funcs.at(i)->remove_const_params())) {
+      LOG_WARN("failed to remove const params in window function", K(ret));
+    }
+  }
+  return ret;
+}
+
 int ObSelectLogPlan::candi_allocate_window_function()
 {
   int ret = OB_SUCCESS;
@@ -1731,6 +1745,8 @@ int ObSelectLogPlan::candi_allocate_window_function()
     LOG_WARN("failed to append exprs", K(ret));
   } else if (OB_FAIL(candi_allocate_subplan_filter_for_exprs(candi_subquery_exprs))) {
     LOG_WARN("failed to do allocate subplan filter", K(ret));
+  } else if (OB_FAIL(remove_const_in_window_functions(stmt->get_window_func_exprs()))) {
+    LOG_WARN("failed to remove const in window functions", K(ret));
   } else if (stmt->get_window_func_count() > 0) {
     ObSEArray<CandidatePlan, 8> winfunc_plans;
     CandidatePlan winfunc_plan;
diff --git a/src/sql/optimizer/ob_select_log_plan.h b/src/sql/optimizer/ob_select_log_plan.h
index cc430b55d3..640c3f571c 100644
--- a/src/sql/optimizer/ob_select_log_plan.h
+++ b/src/sql/optimizer/ob_select_log_plan.h
@@ -183,6 +183,7 @@ private:
       common::ObIArray<MergeKeyInfo*>& merge_keys);
 
   int candi_allocate_window_function();
+  int remove_const_in_window_functions(ObIArray<ObWinFunRawExpr *> &win_funcs);
 
   int candi_allocate_temp_table_insert();
 
diff --git a/src/sql/resolver/expr/ob_raw_expr.cpp b/src/sql/resolver/expr/ob_raw_expr.cpp
index e309c57779..2b9d4206af 100644
--- a/src/sql/resolver/expr/ob_raw_expr.cpp
+++ b/src/sql/resolver/expr/ob_raw_expr.cpp
@@ -3579,6 +3579,42 @@ int ObWindow::assign(const ObWindow& other)
   return ret;
 }
 
+int ObWindow::remove_const_params()
+{
+  int ret = OB_SUCCESS;
+  int64_t cnt_part_expr = 0;
+  int64_t cnt_order_item = 0;
+  for (int64_t i = 0; OB_SUCC(ret) && i < partition_exprs_.count(); ++i) {
+    if (OB_ISNULL(partition_exprs_.at(i))) {
+      ret = OB_ERR_UNEXPECTED;
+      LOG_WARN("get unexpected null", K(ret));
+    } else if (partition_exprs_.at(i)->has_const_or_const_expr_flag()) {
+      /*do nothing */
+    } else {
+      partition_exprs_.at(cnt_part_expr++) = partition_exprs_.at(i);
+    }
+  }
+  for (int64_t i = 0; OB_SUCC(ret) && i < order_items_.count(); ++i) {
+    if (OB_ISNULL(order_items_.at(i).expr_)) {
+      ret = OB_ERR_UNEXPECTED;
+      LOG_WARN("get unexpected null", K(ret));
+    } else if (order_items_.at(i).expr_->has_const_or_const_expr_flag()) {
+      /*do nothing */
+    } else {
+      order_items_.at(cnt_order_item++) = order_items_.at(i);
+    }
+  }
+  if (OB_SUCC(ret)) {
+    while (partition_exprs_.count() > cnt_part_expr) {
+      partition_exprs_.pop_back();
+    }
+    while (order_items_.count() > cnt_order_item) {
+      order_items_.pop_back();
+    }
+  }
+  return ret;
+}
+
 void ObWinFunRawExpr::clear_child()
 {
   func_type_ = T_MAX;
diff --git a/src/sql/resolver/expr/ob_raw_expr.h b/src/sql/resolver/expr/ob_raw_expr.h
index 13ea887dc3..bd6af0a54c 100644
--- a/src/sql/resolver/expr/ob_raw_expr.h
+++ b/src/sql/resolver/expr/ob_raw_expr.h
@@ -3759,8 +3759,8 @@ public:
   {
     return order_items_;
   }
-
   int assign(const ObWindow &other);
+  int remove_const_params();
 
   common::ObArray<ObRawExpr *, common::ModulePageAllocator, true> partition_exprs_;
   common::ObArray<OrderItem, common::ModulePageAllocator, true> order_items_;