Question

我正在尝试在mysql中编写几个数据帧。我使用mysql.connector进行连接，并使用 sqlalchemy 创建引擎。

大多数数据帧均已正确写入数据库。不幸的是，应用程序停止并显示以下错误：

sqlalchemy.exc.DatabaseError: (mysql.connector.errors.DatabaseError) 2006 (HY000): MySQL server has gone away
...
During handling of the above exception, another exception occurred:
...
_mysql_connector.MySQLInterfaceError: MySQL server has gone away

由于断开连接的数据帧也是最大的数据帧（棘手文件：198MB），我认为这是由于 MySql-Server设置max_allowed_packet或超时造成的。（As described here）

因此，我已通过'connect_timeout'：900在SQLConnector中扩展了配置文件（见下文）。不幸的是没有结果。我还读到您应该调整MySql服务器的my.cnf。不幸的是我不知道在哪里可以找到它们。经过长时间的搜索，我发现了以下顺序。 C：\ Program Files \ MySQL \ MySQL Server 8.0 \ etc，带有mysqlrouter.conf.sample文件。 Here我已经下载了my.cnf文件并将其放入文件夹中。不幸的是没有结果，因为我不知道如何设置MySql以便服务器使用此文件。

有人知道我该如何解决此错误？或者如何配置MySql Server首选项设置max_allowed_packet或超时？

主要：

   mysqlConnector = MySQLConnector()
   dbConnection = mysqlConnector.init_engine()
   for df_tuple in df_all_tuple:
       df_name = df_tuple[0]
       df = pd.DataFrame(df_tuple[1])
       df.to_sql(con=mydb, name=df_name, if_exists='fail', chunksize=20000)

SQLConnector：

import mysql.connector
from mysql.connector import errorcode
import sqlalchemy as db

config = {
    'user': 'root',
    'password': '',
    'host': '127.0.0.1',
    'database': 'test',
    'raise_on_warnings': True,
    'use_pure': False,
    'autocommit': True,
    'connect_timeout': 900
}


class MySQLConnector:
    def __init__(self):
        connectTest = self.connect()
        print("Connection to database: " + str(connectTest))

    def init_engine(self):
        try:
            connect_string = 'mysql+mysqlconnector://{}:{}@{}/{}?charset=utf8mb4'.format(config.get("user"),
                                                                                         config.get("password"),
                                                                                         config.get("host"),
                                                                                         config.get("database"),
                                                                                         pool_pre_ping=True)
            print("Engine: " + connect_string)
            sqlengine = db.create_engine(connect_string)
        except:
            print("SQLConnector: Sqlalchemy error. Can't create engine....")
        else:
            dbConnection = sqlengine.connect()
            return dbConnection

    def connect(self):
        try:
            con = mysql.connector.connect(**config)
        except mysql.connector.Error as err:
            if err.errno == errorcode.ER_ACCESS_DENIED_ERROR:
                print("Something is wrong with your user name or password")
            elif err.errno == errorcode.ER_BAD_DB_ERROR:
                print("Database does not exist")
                if self.createDB() is True:
                    return self.connect()
            elif err.errno == errorcode.CR_SERVER_GONE_ERROR:
                print("The client couldn't send a question to the server.")
                print("err: " + err)
            elif err.errno == errorcode.CR_SERVER_LOST:
                print(
                    "The client didn't get an error when writing to the server, but it didn't get a full answer (or any answer) to the question.")
                print("err: " + err)
            else:
                print(err)
            return None
        else:
            if con.is_connected():
                db_Info = con.get_server_info()
                print("Connected to MySQL Server version ", db_Info)
            sqlcursor = con.cursor()
            return con

    def createDB(self):
        try:
            mydb = mysql.connector.connect(
                host=config.get("host"),
                user=config.get("user"),
                passwd=config.get("password")
            )
        except mysql.connector.Error as err:
            print(err)
        else:
            sqlcursor = mydb.cursor()
        try:
            sqlcursor.execute('CREATE DATABASE {}'.format(config.get("database")))
        except mysql.connector.Error as err:
            print(err)
            return False
        else:
            print("Database created!")
            return True

Python.Dataframe到MySql：MySQL服务器已消失

0 个答案: