enter

src/gausskernel/optimizer/plan/streamwalker.cpp

@@ -885,7 +885,7 @@ static bool check_trigger_deferable(Relation rel)
 
     List *indexList = (List *)RelationGetIndexList(rel);
 
-    /* no constaint then retrun true directly. */
+    /* 如果没有索引，则直接返回 true */
     if (indexList == NIL) {
         return true;
     }
@@ -893,6 +893,7 @@ static bool check_trigger_deferable(Relation rel)
     foreach (item, indexList) {
         Oid indexoid = lfirst_oid(item);
 
+        /* 在系统缓存中查找索引元组 */
         indexTuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(indexoid));
         if (!HeapTupleIsValid(indexTuple)) {
             ereport(ERROR,
@@ -901,18 +902,22 @@ static bool check_trigger_deferable(Relation rel)
         }
 
         indexStruct = (Form_pg_index)GETSTRUCT(indexTuple);
+
+        /* 检查索引是否有效，无效索引会被跳过 */
         if (!IndexIsValid(indexStruct)) {
             deferablesCheck = true;
             ReleaseSysCache(indexTuple);
             continue;
         }
 
+        /* 如果索引不是立即触发的，则将 deferablesCheck 设置为 true，并释放系统缓存 */
         if (!indexStruct->indimmediate) {
+            deferablesCheck = true;
             ReleaseSysCache(indexTuple);
             continue;
         }
 
-        /* if indexTuple is invalid or normal(not deferable), then cannot pushable. */
+        /* 如果索引是立即触发的，将 deferablesCheck 设置为 true，并释放系统缓存 */
         deferablesCheck = true;
         ReleaseSysCache(indexTuple);
     }
@@ -920,19 +925,21 @@ static bool check_trigger_deferable(Relation rel)
     return deferablesCheck;
 }
 
-static bool table_contain_unsupport_feature(Oid relid, Query* query)
+
+static bool table_contain_unsupport_feature(Oid relid, Query* query)//该函数用于检查指定的表是否包含不支持流式操作的特性
 {
     Relation rel;
     errno_t sprintf_rc = 0;
 
+    // 尝试打开关系（表）
     rel = try_relation_open(relid, NoLock);
     if (rel != NULL) {
-        /* If contains system relation, we will not output the not shipping reasion */
+        // 如果关系属于系统命名空间，不记录不支持的原因
         if (rel->rd_rel->relnamespace == PG_CATALOG_NAMESPACE) {
             u_sess->opt_cxt.not_shipping_info->need_log = false;
         }
 
-        /* globel temp table could not ship */
+        // 全局临时表不支持流操作
         if (rel->rd_rel->relpersistence == RELPERSISTENCE_GLOBAL_TEMP) {
             sprintf_rc = sprintf_s(u_sess->opt_cxt.not_shipping_info->not_shipping_reason,
                 NOTPLANSHIPPING_LENGTH,
@@ -942,7 +949,7 @@ static bool table_contain_unsupport_feature(Oid relid, Query* query)
             return true;
         }
 
-        /* Currently dml with trigger can not get stream plan. */
+        // 当前带有触发器的 DML 操作不支持流操作
         if (rel->rd_rel->relhastriggers && NULL != rel->trigdesc &&
             ((query->commandType == CMD_INSERT && pgxc_has_trigger_for_event(TRIGGER_TYPE_INSERT, rel->trigdesc)) ||
             (query->commandType == CMD_UPDATE && check_trigger_deferable(rel) &&
@@ -963,19 +970,24 @@ static bool table_contain_unsupport_feature(Oid relid, Query* query)
     return false;
 }
 
+
 static bool contain_unsupport_function(Oid funcId)
 {
+    // 如果函数的 Oid 大于等于 FirstNormalObjectId，表示它是用户定义的函数，不支持流式操作
     if (funcId >= FirstNormalObjectId)
         return true;
 
+    // 遍历不支持的函数列表，如果给定的 funcId 匹配其中一个，则表示不支持流式操作
     for (uint i = 0; i < lengthof(unsupport_func); i++) {
         if (funcId == unsupport_func[i])
             return true;
     }
 
+    // 如果没有匹配的不支持函数，返回 false，表示支持流式操作
     return false;
 }
 
+
 static bool contain_unsupport_expression(Node* expr, void* context)
 {
     if (expr == NULL) {