fix test failure

tests/parallel_test/cases.task

@@ -481,7 +481,7 @@
 ,,y,system-test,./pytest.sh python3 ./test.py -f 2-query/countAlwaysReturnValue.py
 ,,y,system-test,./pytest.sh python3 ./test.py -f 2-query/countAlwaysReturnValue.py -R
 ,,y,system-test,./pytest.sh python3 ./test.py -f 2-query/db.py 
-,,y,system-test,./pytest.sh python3 ./test.py -f 2-query/db.py -R
+,,y,system-test,./pytest.sh python3 ./test.py -f 2-query/db.py -N 3 -n 3 -R
 ,,y,system-test,./pytest.sh python3 ./test.py -f 2-query/diff.py
 ,,y,system-test,./pytest.sh python3 ./test.py -f 2-query/diff.py -R
 ,,y,system-test,./pytest.sh python3 ./test.py -f 2-query/distinct.py

tests/system-test/2-query/db.py

@@ -54,7 +54,11 @@ class TDTestCase:
             tdSql.checkData(0, 1, 'debugFlag')
             tdSql.checkData(0, 2, 0)
 
-        tdSql.execute("alter dnode 2 'debugFlag 135'")
+        tdSql.query("show dnode 1 variables like '%debugFlag'")
+        tdSql.checkRows(21)
+
+        tdSql.query("show dnode 1 variables like '____debugFlag'")
+        tdSql.checkRows(2)        
 
     def run(self):  # sourcery skip: extract-duplicate-method, remove-redundant-fstring
         tdSql.prepare(replica = self.replicaVar)