[TD-3192] <feature>: support child table limit and offset.

add test case

tests/pytest/tools/insert-tblimit-tboffset.json

+{
+    "filetype": "insert",
+    "cfgdir": "/etc/taos",
+    "host": "127.0.0.1",
+    "port": 6030,
+    "user": "root",
+    "password": "taosdata",
+    "thread_count": 4,
+    "thread_count_create_tbl": 4,
+    "result_file": "./insert_res.txt",
+    "confirm_parameter_prompt": "no",
+    "insert_interval": 0,
+    "num_of_records_per_req": 100,
+    "max_sql_len": 1024000,
+    "databases": [{
+        "dbinfo": {
+            "name": "db",
+            "drop": "yes",
+            "replica": 1,
+            "days": 10,
+            "cache": 16,
+            "blocks": 8,
+            "precision": "ms",
+            "keep": 365,
+            "minRows": 100,
+            "maxRows": 4096,
+            "comp":2,
+            "walLevel":1,
+            "cachelast":0,
+            "quorum":1,
+            "fsync":3000,
+            "update": 0
+        },
+        "super_tables": [{
+            "name": "stb",
+            "child_table_exists":"no",
+            "childtable_count": 100,
+            "childtable_prefix": "stb_",
+            "auto_create_table": "no",
+            "data_source": "rand",
+            "insert_mode": "taosc",
+            "insert_rows": 1000,
+            "childtable_limit": 33,
+            "childtable_offset": 33,
+            "multi_thread_write_one_tbl": "no",
+            "number_of_tbl_in_one_sql": 0,
+            "rows_per_tbl": 100,
+            "max_sql_len": 1024000,
+            "disorder_ratio": 0,
+            "disorder_range": 1000,
+            "timestamp_step": 1,
+            "start_timestamp": "2020-10-01 00:00:00.000",
+            "sample_format": "csv",
+            "sample_file": "./sample.csv",
+            "tags_file": "",
+            "columns": [{"type": "INT"}, {"type": "DOUBLE", "count":10}, {"type": "BINARY", "len": 16, "count":3}, {"type": "BINARY", "len": 32, "count":6}],
+            "tags": [{"type": "TINYINT", "count":2}, {"type": "BINARY", "len": 16, "count":5}]
+        }]
+    }]
+}

tests/pytest/tools/taosdemoTestLimitOffset.py

+###################################################################
+#           Copyright (c) 2016 by TAOS Technologies, Inc.
+#                     All rights reserved.
+#
+#  This file is proprietary and confidential to TAOS Technologies.
+#  No part of this file may be reproduced, stored, transmitted,
+#  disclosed or used in any form or by any means other than as
+#  expressly provided by the written permission from Jianhui Tao
+#
+###################################################################
+
+# -*- coding: utf-8 -*-
+
+import sys
+import os
+from util.log import *
+from util.cases import *
+from util.sql import *
+from util.dnodes import *
+
+
+class TDTestCase:
+    def init(self, conn, logSql):
+        tdLog.debug("start to execute %s" % __file__)
+        tdSql.init(conn.cursor(), logSql)
+        
+        self.numberOfTables = 10000
+        self.numberOfRecords = 100
+
+    def getBuildPath(self):
+        selfPath = os.path.dirname(os.path.realpath(__file__))
+
+        if ("community" in selfPath):
+            projPath = selfPath[:selfPath.find("community")]
+        else:
+            projPath = selfPath[:selfPath.find("tests")]
+
+        for root, dirs, files in os.walk(projPath):
+            if ("taosd" in files):
+                rootRealPath = os.path.dirname(os.path.realpath(root))
+                if ("packaging" not in rootRealPath):
+                    buildPath = root[:len(root)-len("/build/bin")]
+                    break
+        return buildPath
+        
+    def run(self):
+        tdSql.prepare()
+        buildPath = self.getBuildPath()
+        if (buildPath == ""):
+            tdLog.exit("taosd not found!")
+        else:
+            tdLog.info("taosd found in %s" % buildPath)
+        binPath = buildPath+ "/build/bin/"
+        os.system("%staosdemo -f tools/insert-tblimit-tboffset.json" % binPath)
+
+        tdSql.execute("use db")
+        tdSql.query("select count(tbname) from db.stb")
+        tdSql.checkData(0, 0, 100)
+        tdSql.query("select count(*) from db.stb")
+        tdSql.checkData(0, 0, 33000)
+
+    def stop(self):
+        tdSql.close()
+        tdLog.success("%s successfully executed" % __file__)
+
+
+tdCases.addWindows(__file__, TDTestCase())
+tdCases.addLinux(__file__, TDTestCase())