需求场景：
有一业务数据库，使用MySQL 5.5版本，每天会写入大量数据，需要不定期将多表中“指定时期前“的数据进行删除，在SQL SERVER中很容易实现，写几个WHILE循环就搞定，虽然MySQL中也存在类似功能，怎奈自己不精通，于是采用Python来实现
话不多少，上脚本：
# coding: utf-8 import MySQLdb import time import os # delete config # 如果VIEW_OR_RUN = "VIEW",仅生成小批量删除的脚本但不执行 # 如果VIEW_OR_RUN = "RUN",生成小批量删除的脚本并直接调用执行 VIEW_OR_RUN = "VIEW" DELETE_DATABASE_NAME = "" DELETE_TABLE_NAME = "" DELETE_TABLE_KEY = "" DELETE_CONDITION = "" DELETE_ROWS_PER_BATCH = 10000 SLEEP_SECOND_PER_BATCH = 0.5 # MySQL Connection Config Default_MySQL_Host = '192.168.166.169' Default_MySQL_Port = 3358 Default_MySQL_User = "mysql_admin" Default_MySQL_Password = 'mysql@Admin@Pwd' Default_MySQL_Charset = "utf8" Default_MySQL_Connect_TimeOut = 120 Default_MySQL_Socket = "/export/data/mysql/tmp/mysql.sock" # Common config: DATETIME_FORMAT = '%Y-%m-%d %X' EXEC_DETAIL_FILE = 'exec_detail.txt' EXEC_SCRIPT_FILE = 'delete_scripts.sql' def highlight(s): return "%s[30;2m%s%s[1m" % (chr(27), s, chr(27)) def print_warning_message(message): """ 以红色字体显示消息内容 :param message: 消息内容 :return: 无返回值 """ message = str(message) print(highlight('') + "%s[31;1m%s%s[0m" % (chr(27), message, chr(27))) global EXEC_DETAIL_FILE write_file(EXEC_DETAIL_FILE, message) def print_info_message(message): """ 以绿色字体输出提醒性的消息 :param message: 消息内容 :return: 无返回值 """ message = str(message) print(highlight('') + "%s[32;2m%s%s[0m" % (chr(27), message, chr(27))) global EXEC_DETAIL_FILE write_file(EXEC_DETAIL_FILE, message) def write_file(file_path, message): """ 将传入的message追加写入到file_path指定的文件中 请先创建文件所在的目录 :param file_path: 要写入的文件路径 :param message: 要写入的信息 :return: """ file_handle = open(file_path, 'a') file_handle.writelines(message) # 追加一个换行以方便浏览 file_handle.writelines(chr(13)) file_handle.close() def get_user_choose_option(input_options, input_message): while_flag = True choose_option = None while while_flag: print_info_message(input_message) str_input = raw_input("") for input_option in input_options: if str_input.strip() == input_option: choose_option = input_option while_flag = False return choose_option def get_mysql_connection(): """ 根据默认配置返回数据库连接 :return: 数据库连接 """ if Default_MySQL_Host.lower() == 'localhost': conn = MySQLdb.connect( host=Default_MySQL_Host, port=Default_MySQL_Port, user=Default_MySQL_User, passwd=Default_MySQL_Password, connect_timeout=Default_MySQL_Connect_TimeOut, charset=Default_MySQL_Charset, db=DELETE_DATABASE_NAME, unix_socket=Default_MySQL_Socket ) else: conn = MySQLdb.connect( host=Default_MySQL_Host, port=Default_MySQL_Port, user=Default_MySQL_User, passwd=Default_MySQL_Password, connect_timeout=Default_MySQL_Connect_TimeOut, charset=Default_MySQL_Charset, db=DELETE_DATABASE_NAME ) return conn def mysql_exec(sql_script, sql_param=None): """ 执行传入的脚本，返回影响行数 :param sql_script: :param sql_param: :return: 脚本最后一条语句执行影响行数 """ try: conn = get_mysql_connection() print_info_message("在服务器{0}上执行脚本:{1}".format( conn.get_host_info(), sql_script)) cursor = conn.cursor() if sql_param is not None: cursor.execute(sql_script, sql_param) else: cursor.execute(sql_script) affect_rows = cursor.rowcount conn.commit() cursor.close() conn.close() return affect_rows except Exception as ex: cursor.close() conn.rollback() raise Exception(str(ex)) def mysql_exec_many(sql_script_list): """ 执行传入的脚本，返回影响行数 :param sql_script_list: 要执行的脚本List,List中每个元素为sql_script, sql_param对 :return: 返回执行每个脚本影响的行数列表 """ try: conn = get_mysql_connection() exec_result_list = [] for sql_script, sql_param in sql_script_list: print_info_message("在服务器{0}上执行脚本:{1}".format( conn.get_host_info(), sql_script)) cursor = conn.cursor() if sql_param is not None: cursor.execute(sql_script, sql_param) else: cursor.execute(sql_script) affect_rows = cursor.rowcount exec_result_list.append("影响行数：{0}".format(affect_rows)) conn.commit() cursor.close() conn.close() return exec_result_list except Exception as ex: cursor.close() conn.rollback() raise Exception(str(ex)) def mysql_query(sql_script, sql_param=None): """ 执行传入的SQL脚本，并返回查询结果 :param sql_script: :param sql_param: :return: 返回SQL查询结果 """ try: conn = get_mysql_connection() print_info_message("在服务器{0}上执行脚本:{1}".format( conn.get_host_info(), sql_script)) cursor = conn.cursor() if sql_param is not None: cursor.execute(sql_script, sql_param) else: cursor.execute(sql_script) exec_result = cursor.fetchall() cursor.close() conn.close() return exec_result except Exception as ex: cursor.close() conn.close() raise Exception(str(ex)) def get_column_info_list(table_name): sql_script = """ DESC {0} """.format(table_name) column_info_list = [] query_result = mysql_query(sql_script=sql_script, sql_param=None) for row in query_result: column_name = row[0] column_type = row[1] column_key = row[3] column_info = column_name, column_key, column_type column_info_list.append(column_info) return column_info_list def get_id_range(): """ 按照传入的表获取要删除数据最大ID、最小ID、删除总行数 :return: 返回要删除数据最大ID、最小ID、删除总行数 """ global DELETE_TABLE_NAME global DELETE_CONDITION sql_script = """ SELECT MAX({2}) AS MAX_ID, MIN({2}) AS MIN_ID, COUNT(1) AS Total_Count FROM {0} WHERE {1}; """.format(DELETE_TABLE_NAME, DELETE_CONDITION, DELETE_TABLE_KEY) query_result = mysql_query(sql_script=sql_script, sql_param=None) max_id, min_id, total_count = query_result[0] # 此处有一坑，可能出现total_count不为0 但是max_id 和min_id 为None的情况 # 因此判断max_id和min_id 是否为NULL if (max_id is None) or (min_id is None): max_id, min_id, total_count = 0, 0, 0 return max_id, min_id, total_count def delete_data(current_min_id, current_max_id): sql_script = """ DELETE FROM {0} WHERE {4} <= {1} and {4} >= {2} AND {3}; """.format(DELETE_TABLE_NAME, current_max_id, current_min_id, DELETE_CONDITION, DELETE_TABLE_KEY ) global EXEC_SCRIPT_FILE global VIEW_OR_RUN if VIEW_OR_RUN == 'RUN': row_count = mysql_exec(sql_script) print_info_message("影响行数：{0}".format(row_count)) time.sleep(SLEEP_SECOND_PER_BATCH) else: print_info_message("生成删除脚本(未执行)") print_info_message(sql_script) tmp_script = """ USE {0}; """.format(DELETE_DATABASE_NAME) + sql_script + """ COMMIT; SELECT SLEEP('{0}'); ##=====================================================## """.format(SLEEP_SECOND_PER_BATCH) write_file(file_path=EXEC_SCRIPT_FILE, message=tmp_script) def loop_delete_data(): max_id, min_id, total_count = get_id_range() if min_id == max_id: print_info_message("无数据需要结转") return current_min_id = min_id global DELETE_ROWS_PER_BATCH while current_min_id <= max_id: print_info_message("*" * 70) current_max_id = current_min_id + DELETE_ROWS_PER_BATCH delete_data(current_min_id, current_max_id) current_percent = (current_max_id - min_id) * 100.0 / (max_id - min_id) left_rows = max_id - current_max_id if left_rows < 0: left_rows = 0 current_percent_str = "%.2f" % current_percent info = "当前进度{0}/{1},剩余{2},进度为{3}%" info = info.format(current_max_id, max_id, left_rows, current_percent_str) print_info_message(info) current_min_id = current_max_id print_info_message("*" * 70) print_info_message("执行完成") def check_config(): try: global DELETE_DATABASE_NAME global DELETE_TABLE_NAME global DELETE_TABLE_KEY global DELETE_CONDITION global VIEW_OR_RUN if str(DELETE_DATABASE_NAME).strip() == "": print_warning_message("数据库名不能为空") return False if str(DELETE_TABLE_NAME).strip() == "": print_warning_message("表名不能为空") return False if str(DELETE_CONDITION).strip() == "": print_warning_message("删除条件不能为空") return False source_columns_info_list = get_column_info_list(DELETE_TABLE_NAME) column_count = len(source_columns_info_list) primary_key_count = 0 for column_id in range(column_count): source_column_name, source_column_key, source_column_type = source_columns_info_list[column_id] if source_column_key.lower() == 'pri': primary_key_count += 1 if not ('int' in str(source_column_type).lower()): print_warning_message("主键不为int或bigint") return False else: global DELETE_TABLE_KEY DELETE_TABLE_KEY = source_column_name if primary_key_count == 0: print_warning_message("未找到主键，不瞒足迁移条件") return False if primary_key_count > 1: print_warning_message("要删除的表使用复合主键，不满足迁移条件") return False return True except Exception as ex: print_warning_message("执行出现异常，异常为{0}".format(ex.message)) return False def clean_env(): global DELETE_DATABASE_NAME global DELETE_TABLE_NAME global DELETE_TABLE_KEY global DELETE_CONDITION global VIEW_OR_RUN DELETE_DATABASE_NAME = "" DELETE_TABLE_NAME = "" DELETE_TABLE_KEY = "" DELETE_CONDITION = "" VIEW_OR_RUN = "VIEW" if os.path.exists(EXEC_SCRIPT_FILE): os.remove(EXEC_SCRIPT_FILE) if os.path.exists(EXEC_DETAIL_FILE): os.remove(EXEC_DETAIL_FILE) def user_confirm(): if VIEW_OR_RUN == 'RUN': info = """ 您将在服务器{0}上{1}中删除表{2}中数据 删除数据条件为: DELETE FROM {3} WHERE {4} """ else: info = """ 将生成在服务器{0}上{1}中删除表{2}中数据的脚本 删除数据条件为: DELETE FROM {3} WHERE {4} """ info = info.format(Default_MySQL_Host, DELETE_DATABASE_NAME, DELETE_TABLE_NAME, DELETE_TABLE_NAME, DELETE_CONDITION) if VIEW_OR_RUN == "RUN": print_warning_message(info) else: print_info_message(info) input_options = ['yes', 'no'] input_message = """ 请输入yes继续或输入no退出，yes/no? """ user_option = get_user_choose_option(input_options=input_options, input_message=input_message) if user_option == "no": return False else: return True def delete_table_data(database_name, table_name, delete_condition, is_run, is_need_confirm): global DELETE_DATABASE_NAME global DELETE_TABLE_NAME global DELETE_TABLE_KEY global DELETE_CONDITION global VIEW_OR_RUN DELETE_DATABASE_NAME = database_name DELETE_TABLE_NAME = table_name DELETE_CONDITION = delete_condition DELETE_TABLE_KEY = '' if is_run: VIEW_OR_RUN = "RUN" else: VIEW_OR_RUN = "VIEW" check_result = check_config() if not check_result: return if is_need_confirm: confirm_result = user_confirm() else: confirm_result = True if confirm_result: loop_delete_data() def main(): clean_env() delete_table_data(database_name="db001", table_name="tb2001", delete_condition="dt<'2017-09-01'", is_run=True, is_need_confirm=True) if __name__ == '__main__': main()
执行效果：
实现原理：
由于表存在自增ID，于是给我们增量循环删除的机会，查找出满足删除条件的最大值ID和最小值ID，然后按ID 依次递增，每次小范围内(如10000条)进行删除。
实现优点：
实现“小斧子砍大柴”的效果，事务小，对线上影响较小，打印出当前处理到的“ID”，可以随时关闭，稍微修改下代码便可以从该ID开始，方便。
实现不足：
为防止主从延迟太高，采用每次删除SLEEP1秒的方式，相对比较糙，最好的方式应该是周期扫描这条复制链路，根据延迟调整SLEEP的周期，反正都脚本化，再智能化点又何妨！
本文重点依旧是妹子，不能让诸位看官白跑一趟，是不！！！
