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src/gausskernel/optimizer/path/costsize.cpp

@@ -5775,7 +5775,7 @@ static double calc_joinrel_size_estimate(PlannerInfo* root, double outer_rows, d
             (errmodule(MOD_OPT),
                 errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE),
                 errmsg("unrecognized join type when calculate joinrel size estimate: %d", (int)jointype)));
-        nrows = 0; // 如果连接类型未知，则将行数估算为0
+        nrows = 0; // <EFBFBD><EFBFBD><EFBFBD>果连接类型未知，则将行数估算为0
     } break;
 }
 
@@ -6045,31 +6045,41 @@ inline void set_rel_encode_info_if_vectorized(PlannerInfo *root, RelOptInfo *rel
  * The per-attribute width estimates are cached for possible re-use while
  * building join relations.
  */
+// 设置关系的宽度估计
 void set_rel_width(PlannerInfo* root, RelOptInfo* rel)
 {
+    // 获取关系的OID
     Oid reloid = planner_rt_fetch(rel->relid, root)->relid;
+    // 初始化元组宽度为0
     int32 tuple_width = 0;
+    // 初始化是否有整行变量的标志为false
     bool have_wholerow_var = false;
+    // 遍历关系的目标列表
     ListCell* lc = NULL;
 
     foreach (lc, rel->reltargetlist) {
         Node* node = (Node*)lfirst(lc);
 
+        // 检查节点是否是一个变量
         if (IsA(node, Var)) {
             Var* var = (Var*)node;
             int ndx;
             int32 item_width;
 
+            // 断言：变量的varno必须与关系的relid匹配
             AssertEreport(var->varno == rel->relid,
                 MOD_OPT,
                 "The varno does not match to relid when setting the estimated output width of a base relation.");
+            // 断言：变量的varattno必须大于等于关系的最小属性
             AssertEreport(var->varattno >= rel->min_attr,
                 MOD_OPT,
                 "The varattno is less than min_attr when setting the estimated output width of a base relation.");
+            // 断言：变量的varattno必须小于等于关系的最大属性
             AssertEreport(var->varattno <= rel->max_attr,
                 MOD_OPT,
                 "The varattno is larger than max_attr when setting the estimated output width of a base relation.");
 
+            // 计算属性在关系中的索引
             ndx = var->varattno - rel->min_attr;
 
             /*
@@ -6092,31 +6102,42 @@ void set_rel_width(PlannerInfo* root, RelOptInfo* rel)
             }
 
             /* Try to get column width from statistics */
-            if (reloid != InvalidOid && var->varattno > 0) {
-                Oid targetid = reloid;
-                bool ispartition = false;
-                RangeTblEntry* rte = planner_rt_fetch(rel->relid, root);
+                            // 检查关系的OID是否有效，以及变量的varattno是否大于0
+                if (reloid != InvalidOid && var->varattno > 0) {
+                    Oid targetid = reloid;
+                    bool ispartition = false;
+                    RangeTblEntry* rte = planner_rt_fetch(rel->relid, root);
 
-                if (rte->isContainPartition) {
-                    AssertEreport(OidIsValid(rte->partitionOid),
-                        MOD_OPT,
-                        "The partitionOid is invalid when setting the estimated output width of a base relation.");
-                    targetid = rte->partitionOid;
-                    ispartition = true;
-                }
+                    // 如果关系包含分区，则使用分区OID作为目标ID
+                    if (rte->isContainPartition) {
+                        // 断言：分区OID必须有效
+                        AssertEreport(OidIsValid(rte->partitionOid),
+                            MOD_OPT,
+                            "The partitionOid is invalid when setting the estimated output width of a base relation.");
+                        targetid = rte->partitionOid;
+                        ispartition = true;
+                    }
 
-                if (rte->isContainSubPartition) {
-                    Assert(OidIsValid(rte->partitionOid));
-                    targetid = rte->subpartitionOid;
-                    ispartition = true;
-                }
+                    // 如果关系包含子分区，则使用子分区OID作为目标ID
+                    if (rte->isContainSubPartition) {
+                        // 断言：分区OID必须有效
+                        Assert(OidIsValid(rte->partitionOid));
+                        targetid = rte->subpartitionOid;
+                        ispartition = true;
+                    }
+
+                    // 获取属性的平均宽度
+                    item_width = get_attavgwidth(targetid, var->varattno, ispartition);
+                    // 如果属性宽度大于0
+                    if (item_width > 0) {
+                        // 将属性宽度存储在关系的attr_widths数组中
+                        rel->attr_widths[ndx] = item_width;
+                        // 增加元组宽度
+                        tuple_width += item_width;
+                        // 设置关系的编码信息（如果是矢量化计划）
+                        set_rel_encode_info_if_vectorized(root, rel, var->vartype, item_width);
+                        continue;
 
-                item_width = get_attavgwidth(targetid, var->varattno, ispartition);
-                if (item_width > 0) {
-                    rel->attr_widths[ndx] = item_width;
-                    tuple_width += item_width;
-                    set_rel_encode_info_if_vectorized(root, rel, var->vartype, item_width);
-                    continue;
                 }
             }
 
@@ -6132,7 +6153,7 @@ void set_rel_width(PlannerInfo* root, RelOptInfo* rel)
             rel->attr_widths[ndx] = item_width;
             tuple_width += item_width;
             set_rel_encode_info_if_vectorized(root, rel, var->vartype, item_width);
-        } else if (IsA(node, PlaceHolderVar)) {
+        } else if (IsA(node, PlaceHolderVar)) {// 如果变量不是Var类型，则进入这个分支
             PlaceHolderVar* phv = (PlaceHolderVar*)node;
             PlaceHolderInfo* phinfo = find_placeholder_info(root, phv, false);
 
@@ -6146,13 +6167,17 @@ void set_rel_width(PlannerInfo* root, RelOptInfo* rel)
              */
             int32 item_width;
 
-            item_width = get_typavgwidth(exprType(node), exprTypmod(node));
-            AssertEreport(item_width > 0,
-                MOD_OPT,
-                "The estimated average width of values of the type is not larger than 0"
-                "when setting the estimated output width of a base relation.");
+                    // 获取节点的类型和类型修饰符，然后计算平均宽度
+                    item_width = get_typavgwidth(exprType(node), exprTypmod(node));
+                    // 断言：宽度必须大于0
+                    AssertEreport(item_width > 0,
+                        MOD_OPT,
+                        "The estimated average width of values of the type is not larger than 0"
+                        "when setting the estimated output width of a base relation.");
 
-            tuple_width += item_width;
+                    // 增加元组宽度
+                    tuple_width += item_width;
+                    // 设置关系的编码信息（如果是矢量化计划）
             set_rel_encode_info_if_vectorized(root, rel, exprType(node), item_width);
         }
     }
@@ -6161,7 +6186,8 @@ void set_rel_width(PlannerInfo* root, RelOptInfo* rel)
      * If we have a whole-row reference, estimate its width as the sum of
      * per-column widths plus sizeof(HeapTupleHeaderData).
      */
-    if (have_wholerow_var) {
+       if (have_wholerow_var) {
+        // 如果有整行变量，计算整行的宽度
         int32 wholerow_width = sizeof(HeapTupleHeaderData);
 
         if (reloid != InvalidOid) {
@@ -6180,18 +6206,31 @@ void set_rel_width(PlannerInfo* root, RelOptInfo* rel)
                 partid = rte->subpartitionOid;
             }
 
-            /* Real relation, so estimate true tuple width */
+            // 获取关系数据的宽度，包括主表和分区
             wholerow_width += get_relation_data_width(reloid, partid, rel->attr_widths - rel->min_attr);
         } else {
-            /* Do what we can with info for a phony rel */
+            // 获取关系的宽度，包括所有属性
             AttrNumber i;
-
             for (i = 1; i <= rel->max_attr; i++)
                 wholerow_width += rel->attr_widths[i - rel->min_attr];
         }
 
+        // 将整行的宽度设置到关系的属性宽度数组中
         rel->attr_widths[0 - rel->min_attr] = wholerow_width;
 
+        // 增加元组宽度
+        tuple_width += wholerow_width;
+    }
+
+    // 断言：元组宽度必须大于或等于0
+    AssertEreport(tuple_width >= 0,
+        MOD_OPT,
+        "The estimated width of tuple is less than 0"
+        "when setting the estimated output width of a base relation.");
+    // 将元组宽度设置到关系的宽度属性中
+    rel->width = tuple_width;
+
+
         /*
          * Include the whole-row Var as part of the output tuple.  Yes, that
          * really is what happens at runtime.
@@ -6225,32 +6264,35 @@ void set_rel_width(PlannerInfo* root, RelOptInfo* rel)
  */
 double relation_byte_size(double tuples, int width, bool vectorized, bool aligned, bool issort, bool indexsort)
 {
+    // 断言：宽度必须大于或等于0
     Assert(width >= 0);
+
+    // 计算头部大小，根据是否排序和是否索引排序来选择不同的头部类型
     size_t header_size = (issort && indexsort) ? sizeof(IndexTupleData) : sizeof(HeapTupleHeaderData);
+
     if (aligned) {
         if (vectorized)
+            // 返回关系的字节大小，考虑了对齐
             return tuples * (TUPLE_OVERHEAD(true) + width);
         else
+            // 返回关系的字节大小，考虑了对齐和分配块大小
             return tuples *
                    (TUPLE_OVERHEAD(issort) + alloc_trunk_size(MAXALIGN((uintptr_t)width) + MAXALIGN(header_size)));
     } else {
+        // 返回关系的字节大小，不考虑对齐
         return tuples * (MAXALIGN((uintptr_t)width) + MAXALIGN(header_size));
     }
 }
 
-/*
- * page_size
- *	  Returns an estimate of the number of pages covered by a given
- *	  number of tuples of a given width (size in bytes).
- */
 double page_size(double tuples, int width)
 {
+    // 计算关系所占用的页数
     return ceil(relation_byte_size(tuples, width, false) / BLCKSZ);
 }
 
-/* it used to compute page_size in createplan.cpp */
 double cost_page_size(double tuples, int width)
 {
+    // 计算成本中的页数
     return page_size(tuples, width);
 }
 
@@ -6261,8 +6303,11 @@ double cost_page_size(double tuples, int width)
  */
 void restore_hashjoin_cost(Path* path)
 {
+    // 如果启用了哈希连接成本修改并且路径是哈希路径
     if (u_sess->attr.attr_sql.enable_change_hjcost && IsA(path, HashPath)) {
+        // 获取内部路径
         Path* innerpath = ((HashPath*)path)->jpath.innerjoinpath;
+        // 恢复哈希连接的启动成本
         path->startup_cost += innerpath->total_cost - innerpath->startup_cost;
     }
 }
@@ -6385,34 +6430,42 @@ void hybrid_samplescangetsamplesize(PlannerInfo* root, RelOptInfo* baserel, List
     ListCell* lc = NULL;
     uint16 i = 0;
 
+    // 断言：样本参数数量必须等于2
     AssertEreport(SAMPLEARGSNUM == list_length(paramexprs),
         MOD_OPT,
         "The number of sample percentage info does not equal 2"
         "when setting the estimated output width of a base relation.");
+
     foreach (lc, paramexprs) {
         Node* paramnode = (Node*)lfirst(lc);
         Node* pctnode = estimate_expression_value(root, paramnode);
         float4 samplefract = 0.0;
+
+        // 检查是否成功估算了百分比值
         if (likely(pctnode)) {
             samplefract = get_samplefract(pctnode);
         } else {
+            // 如果估算失败，报告错误
             ereport(ERROR,
                 (errcode(ERRCODE_UNEXPECTED_NULL_VALUE),
                     errmsg("Fail to estimate expression value.")));
         }
 
         if (i == SYSTEM_SAMPLE) {
-            /* We'll visit a sample of the pages ... */
+            /* 我们将访问页面的一部分... */
+            // 更新关系的页面数，以考虑样本抽取
             baserel->pages = clamp_row_est(baserel->pages * samplefract);
         }
 
-        /* ... and hopefully get a representative number of tuples from them */
+        /* ... 并希望从中获得代表性的元组数量 */
+        // 更新关系的元组数，以考虑样本抽取
         baserel->tuples = clamp_row_est(baserel->tuples * samplefract);
 
         i++;
     }
 }
 
+
 /*
  * copy_mem_info
  *	copy OpMemInfo structure from source to dest
@@ -6471,22 +6524,26 @@ bool has_complicate_hashkey(List* hashclauses, Relids inner_relids)
 {
     ListCell* lc = NULL;
 
+    // 遍历哈希关联条件列表
     foreach (lc, hashclauses) {
         RestrictInfo* restrictinfo = (RestrictInfo*)lfirst(lc);
         Node* innerkey = NULL;
 
+        // 断言：条件节点必须是 RestrictInfo 类型
         AssertEreport(IsA(restrictinfo, RestrictInfo),
             MOD_OPT,
             "The nodeTag of restrictinfo is not T_RestrictInfo"
             "when setting the estimated output width of a base relation.");
 
         /*
-         * First we have to figure out which side of the hashjoin clause
-         * is the inner side.
+         * 首先，我们需要确定哈希连接条件的哪一侧是内部侧。
+         * 如果 restrictinfo 的右侧关系 ID 是 inner_relids 的子集，
+         * 那么 innerkey 就是 restrictinfo 条件的右操作数，否则就是左操作数。
          */
         if (bms_is_subset(restrictinfo->right_relids, inner_relids)) {
             innerkey = get_rightop(restrictinfo->clause);
         } else {
+            // 断言：左侧关系 ID 必须是 inner_relids 的子集
             AssertEreport(bms_is_subset(restrictinfo->left_relids, inner_relids),
                 MOD_OPT,
                 "The left relids is not subset of the relids of inner side"
@@ -6494,7 +6551,7 @@ bool has_complicate_hashkey(List* hashclauses, Relids inner_relids)
             innerkey = get_leftop(restrictinfo->clause);
         }
 
-        /* Judge if the inner key is simple var */
+        /* 判断内部键是否为简单变量 */
         if (innerkey != NULL && !IsA(innerkey, Var) &&
             !(IsA(innerkey, RelabelType) && IsA(((RelabelType*)innerkey)->arg, Var)))
             return true;
@@ -6503,6 +6560,7 @@ bool has_complicate_hashkey(List* hashclauses, Relids inner_relids)
     return false;
 }
 
+
 /*
  * calc_distributekey_width
  *	Optimizer will add distribute key in the targetlist if not found in plan
@@ -6518,30 +6576,31 @@ bool has_complicate_hashkey(List* hashclauses, Relids inner_relids)
  */
 static int calc_distributekey_width(Path* path, int* width, bool vectorized, bool aligned)
 {
-    int num = 0;
+    int num = 0; // 初始化计数器为0
     ListCell* lc = NULL;
 
-    /* Only do this for redistribute stream, since only redistribute has distribute keys */
+    /* 只对分发流执行此操作，因为只有分发流有分发键 */
     if (IsA(path, StreamPath) && ((StreamPath*)path)->type == STREAM_REDISTRIBUTE) {
-        foreach (lc, path->distribute_keys) {
+        foreach (lc, path->distribute_keys) { // 遍历分发键列表
             Node* node = (Node*)lfirst(lc);
-            if (!list_member(path->parent->reltargetlist, node)) {
-                num++;
-                int32 item_width = get_typavgwidth(exprType(node), exprTypmod(node));
+            if (!list_member(path->parent->reltargetlist, node)) { // 检查节点是否不在目标列表中
+                num++; // 增加计数器
+                int32 item_width = get_typavgwidth(exprType(node), exprTypmod(node)); // 获取类型的平均宽度
                 AssertEreport(item_width > 0,
                     MOD_OPT,
                     "The item width is not larger than 0 when setting the estimated output width of a base relation.");
                 if (vectorized)
-                    *width += columnar_get_col_width(exprType(node), item_width, aligned);
+                    *width += columnar_get_col_width(exprType(node), item_width, aligned); // 计算列宽度
                 else
-                    *width += item_width;
+                    *width += item_width; // 直接累加宽度
             }
         }
     }
 
-    return num;
+    return num; // 返回计数器的值
 }
 
+
 /*
  * get_path_actual_total_width
  *	In PG optimizer, only width of row engine is estimated, and it has
@@ -6561,33 +6620,35 @@ static int calc_distributekey_width(Path* path, int* width, bool vectorized, boo
  */
 int get_path_actual_total_width(Path* path, bool vectorized, OpType type, int newcol)
 {
-    int num_new_col = 0;
-    int width = 0;
-    bool aligned = (type >= OP_SORT);
+    int num_new_col = 0;          // 用于记录新列的数量
+    int width = 0;                // 用于记录宽度
+    bool aligned = (type >= OP_SORT); // 根据操作类型是否需要对齐
 
     if (path->parent == NULL) {
-        return COL_TUPLE_WIDTH;
+        return COL_TUPLE_WIDTH; // 如果路径的父节点为空，则返回默认列元组宽度
     }
 
-    /* For redistribute, we will add unmatched distribute key into targetlist, so count this */
+    // 计算分发键的宽度，并将结果累加到 width 中
     num_new_col = calc_distributekey_width(path, &width, vectorized, aligned);
 
     if (vectorized) {
         switch (type) {
             case OP_HASHJOIN:
+                // 计算哈希连接操作的宽度
                 width += path->parent->encodedwidth +
                          SIZE_COL_VALUE * (list_length(path->parent->reltargetlist) + num_new_col + newcol);
                 break;
             case OP_HASHAGG:
+                // 计算哈希聚合操作的宽度
                 width += path->parent->encodedwidth + TUPLE_OVERHEAD(true) + sizeof(void*) * 2 +
                          SIZE_COL_VALUE * (list_length(path->parent->reltargetlist) + num_new_col + newcol);
                 break;
             case OP_SORT:
                 if (width != 0 || path->parent->encodednum != 0)
-                    newcol += 1;
+                    newcol += 1; // 如果排序操作，且宽度不为0或者已编码的列数不为0，增加新列
                 /* No need break here. */
             case OP_MATERIAL:
-                /* don't know encoded width of each column, just average them for a rough estimation */
+                /* 不知道每列的编码宽度，只是对它们进行粗略估算的平均值 */
                 if (path->parent->encodednum > 0)
                     width += path->parent->encodednum *
                              alloc_trunk_size(path->parent->encodedwidth / path->parent->encodednum);
@@ -6597,48 +6658,54 @@ int get_path_actual_total_width(Path* path, bool vectorized, OpType type, int ne
                 break;
         }
     } else {
-        width += path->parent->width;
+        width += path->parent->width; // 非矢量化操作，直接使用父节点的宽度
     }
 
-    return width;
+    return width; // 返回计算得到的总宽度
 }
 
+
 /*
  * get_subqueryscan_stream_cost
  * 	get stream_cost of a subquery
  */
 static Cost get_subqueryscan_stream_cost(Plan* subplan)
 {
-    Cost stream_cost = 0;
+    Cost stream_cost = 0; // 初始化流成本为0
 
     if (subplan == NULL)
-        return stream_cost;
+        return stream_cost; // 如果子计划为空，直接返回0
 
     switch (nodeTag(subplan)) {
         case T_HashJoin:
         case T_VecHashJoin:
+            // 对于哈希连接计划节点，递归调用左子树的流成本
             stream_cost = get_subqueryscan_stream_cost(subplan->lefttree);
             break;
 
         case T_NestLoop:
         case T_VecNestLoop:
+            // 对于嵌套循环计划节点，递归调用右子树的流成本
             stream_cost = get_subqueryscan_stream_cost(subplan->righttree);
             break;
 
         case T_MergeJoin:
         case T_VecMergeJoin:
+            // 对于归并连接计划节点，递归调用右子树的流成本
             stream_cost = get_subqueryscan_stream_cost(subplan->righttree);
             break;
 
         case T_Stream:
         case T_VecStream:
+            // 对于流计划节点，流成本等于启动成本
             stream_cost = subplan->startup_cost;
             break;
 
         default:
+            // 对于其他计划节点类型，递归调用左子树的流成本
             stream_cost = get_subqueryscan_stream_cost(subplan->lefttree);
             break;
     }
 
-    return stream_cost;
+    return stream_cost; // 返回计算得到的流成本
 }