diff --git a/src/common/backend/utils/misc/guc.cpp b/src/common/backend/utils/misc/guc.cpp
index d4315717dd5296d1799552c1ff270c8623eb0dbf..ad245c9fe46db9b0100d38ad10851c9d81e9f985 100755
--- a/src/common/backend/utils/misc/guc.cpp
+++ b/src/common/backend/utils/misc/guc.cpp
@@ -1537,7 +1537,7 @@ static void InitConfigureNamesBool()
             CLIENT_CONN_STATEMENT,
             gettext_noop("Sets the current transaction's read-only status."),
             NULL,
-            GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE},
+            GUC_NO_RESET | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE},
             &u_sess->attr.attr_common.XactReadOnly,
             false,
             check_transaction_read_only,
@@ -8034,6 +8034,21 @@ int set_config_option(const char* name, const char* value, GucContext context, G
         }
     }
 
+    if (record->flags & GUC_NO_RESET) {
+        if (value == NULL) {
+            ereport(elevel,
+                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+                    errmsg("cannot reset parameter \"%s\"", name)));
+            return 0;
+        }
+
+        if (action == GUC_ACTION_SAVE) {
+            ereport(elevel,
+                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+                    errmsg("cannot set parameter \"%s\" locally within functions", name)));
+            return 0;
+        }
+    }
     /*
      * Should we set reset/stacked values?	(If so, the behavior is not
      * transactional.)	This is done either when we get a default value from
diff --git a/src/common/backend/utils/misc/guc/guc_storage.cpp b/src/common/backend/utils/misc/guc/guc_storage.cpp
index 6a9afc4c18af231ac0cfbbbde7d78a96ebcb440a..153f4a5765d04baa461e26da9b201083a9062111 100755
--- a/src/common/backend/utils/misc/guc/guc_storage.cpp
+++ b/src/common/backend/utils/misc/guc/guc_storage.cpp
@@ -627,7 +627,7 @@ static void InitStorageConfigureNamesBool()
             gettext_noop("Whether to defer a read-only serializable transaction until it can be executed with no "
                         "possible serialization failures."),
             NULL,
-            GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE},
+            GUC_NO_RESET | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE},
             &u_sess->attr.attr_storage.XactDeferrable,
             false,
             check_transaction_deferrable,
@@ -4580,7 +4580,7 @@ static void InitStorageConfigureNamesString()
             CLIENT_CONN_STATEMENT,
             gettext_noop("Sets the current transaction's isolation level."),
             NULL,
-            GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE},
+            GUC_NO_RESET | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE},
             &u_sess->attr.attr_storage.XactIsoLevel_string,
             "default",
             check_XactIsoLevel,
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index c884de5a0ba2982d8565653a10a32b3e22007ea6..18f689dff62f3157f807e38092161e58d7b3fc3f 100755
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -207,6 +207,7 @@ typedef struct {
 #define GUC_LIST_INPUT 0x0001         /* input can be list format */
 #define GUC_LIST_QUOTE 0x0002         /* double-quote list elements */
 #define GUC_NO_SHOW_ALL 0x0004        /* exclude from SHOW ALL */
+#define GUC_NO_RESET 0x10000          /* disallow reset for specific variable */
 #define GUC_NO_RESET_ALL 0x0008       /* exclude from RESET ALL */
 #define GUC_REPORT 0x0010             /* auto-report changes to client */
 #define GUC_NOT_IN_SAMPLE 0x0020      /* not in postgresql.conf.sample */
diff --git a/src/test/regress/expected/transactions_test.out b/src/test/regress/expected/transactions_test.out
index b32f061f3f864f94da5bba2dd02f6e08c5e03588..76259411b5d7fcf3fb2a17f3a4a703a1bd5e4df9 100644
--- a/src/test/regress/expected/transactions_test.out
+++ b/src/test/regress/expected/transactions_test.out
@@ -1,3 +1,37 @@
+CREATE TABLE no_reset_test(a int);
+insert into no_reset_test values(1);
+-- Test transaction variable cannot be reset.
+BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ;
+select count(*) from no_reset_test;
+ count 
+-------
+     1
+(1 row)
+
+reset transaction_isolation; --error
+ERROR:  cannot reset parameter "transaction_isolation"
+END;
+BEGIN TRANSACTION READ ONLY;
+select count(*) from no_reset_test;
+ count 
+-------
+     1
+(1 row)
+
+reset transaction_read_only; --error
+ERROR:  cannot reset parameter "transaction_read_only"
+END;
+BEGIN TRANSACTION DEFERRABLE;
+select count(*) from no_reset_test;
+ count 
+-------
+     1
+(1 row)
+
+reset transaction_deferrable; --error
+ERROR:  cannot reset parameter "transaction_deferrable"
+END;
+DROP TABLE no_reset_test;
 SET SESSION CHARACTERISTICS AS TRANSACTION READ ONLY;
 START TRANSACTION READ WRITE;
 CREATE TABLE transaction_test_table(a int);
diff --git a/src/test/regress/sql/transactions_test.sql b/src/test/regress/sql/transactions_test.sql
index a384641a389064f984b909e2caf313c0f5af2614..84b079cf03ed3fcbe6c876d6b701ce27d0ea3e8e 100644
--- a/src/test/regress/sql/transactions_test.sql
+++ b/src/test/regress/sql/transactions_test.sql
@@ -1,3 +1,24 @@
+CREATE TABLE no_reset_test(a int);
+insert into no_reset_test values(1);
+
+-- Test transaction variable cannot be reset.
+BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ;
+select count(*) from no_reset_test;
+reset transaction_isolation; --error
+END;
+
+BEGIN TRANSACTION READ ONLY;
+select count(*) from no_reset_test;
+reset transaction_read_only; --error
+END;
+
+BEGIN TRANSACTION DEFERRABLE;
+select count(*) from no_reset_test;
+reset transaction_deferrable; --error
+END;
+
+DROP TABLE no_reset_test;
+
 SET SESSION CHARACTERISTICS AS TRANSACTION READ ONLY;
 START TRANSACTION READ WRITE;
 CREATE TABLE transaction_test_table(a int);