As a website owner, you need to manage the data of viewers and online customers who log in to your website. Well, you cannot store the data manually all the time. Therefore, you need a program to make data storage and collection easier for you. Well, MySQL is the program that can allow website owners to perform these tasks. MySQL is based on a relational database management system (RDBMS). It is one of the most widely used database management systems (DBMS), and due to its open-source licensing, both big and small companies can use it to the fullest without having to worry about the subscription fee.
But, when you are using an open-source application or platform, you are not going to find technical support to resolve any issue that you might come across while using it. It is the web forums and other users of the same open-source platform that can help you out with your problem. To help users who are new to MySQL databases, we are making error resolution a bit easier by providing a list of some of the most common errors which one may experience while using the program. Along with the list of errors, we are also providing the solutions for the same.
Common Errors in MySQL
So now that you have learned about the benefits of using MySQL, it’s time to see the common errors which you might face when working with databases using MySQL.
1. Mysql Server Gone Away
When working with a remote database, one of the most common errors that you will be receiving is the server issues which are presented in the form of MySQL Server Gone Away. If this error is displayed then the server will end the connection after 8 hours if no change is happening in the database. But you can manually set the time limit when you start the mysqld.
Apart from this, another reason why you are receiving this error is that you might have added “close” to your MySQL connection. Once this command is active, all the queries that you are trying to run on the database will not work as there is no closed connection.
- CR_SERVER_GONE_ERROR: This error shows that the client who is trying to access the database is unable to send the question to the database server.
- CR_SERVER_LOST: The client didn’t receive the full answer or, in some cases, any answers from the server end when it has sent the request.
These two errors will occur when someone while using the server database has mistakenly activated the kill function to the running threads. To check if MySQL hasn’t died yet, you can execute the following command mysqladmin version. With this command, you will be able to find the uptime of the database. If due to some reason, mysqld crashed, then you need to focus on finding the reason why it crashed.
Moreover, you can face this error while sending a request to the server which is either incorrect or too large to handle. If mysqld receives a very big packet from a user, it will consider that some error has happened from the user’s end and will break up the connection.
2. Password Fails
Whenever you are making a connection with the MySQL client, it will ask you to enter a password. This password helps in invoking the client program. You can use the following command to enter your password in MySQL:
> mysql -u user_name -p
When prompted, type the password. The password works flawlessly if you have provided the options file or used the command line. But when you enter the password interactively on the Command Prompt when it asks you to enter the password. The error occurs. The reason why the same password fails when you enter it in the command prompt is that the system-provided library which reads the passwords entered by the user limits the password value to a tiny number; in most cases, it is eight.
Well, this is the issue with the system library, and this error has nothing to do with MySQL. To get around this problem, you need to make changes in the password which you are using and get it under the eight-character limit.
3. Too Many Connections
When you are trying to make a connection with the mysqld server, then it means all the available connections are already in use. There are two things you can do here, either you wait for a connection to close so that you can connect yours with the server. Or you can ask the server owner to increase the number of connections to their mysqld.
One thing to keep in mind is that the mysqld server allows max_connections+1 permission. The extra connection which comes with max_connections is reserved for the account which has admin privileges.
4. Out of Memory
Sometimes when you are trying to add new data in MySQL it will show you the “out of memory” error. This happens when there is not enough space in the MySQL memory for the entire request of the query which is issued by you. To fix this error, you need to first check whether the query you have entered is correct or not? Check if the query is intended to return that many rows in a single output. If not, you need to make changes to the query and write the correct one.
On the other hand, if the query is fine and there are no corrections that need to be made, then we need to look for issues caused by MySQL. With the use of quick option results like this: mysql_use_result()
5. The Packet Size is Too Large
There are many reasons for facing this error. A packet can be a single SQL statement that you send to the MySQL server. Also, a single row is sent by you to the server. Lastly, the error could occur when a log event is sent using the replication master server. The largest packet size which MySQL accepts is 1GB. This is the maximum size that can be sent and received from the MySQL server. To increase the size of packet acceptance, you need to write this command:
> mysql –max_allowed_packet=32M
The default value of MySQL is just 64MB, so increasing its size is one thing every user must do before they start working on MySQL. The increase in the variable is a precautionary step to avoid facing errors due to the size.
6. Communication Error
With the newer version of MySQL, or versions after 3.23.40, a user will only receive a communication error if you start the mysqld with a warning. In case you are finding errors in your error logs, it means one of the following issues in your MySQL has caused this problem.
- The error could be due to a program running on your computer that did not call mysql_close() before you exit.
- The client-server is in a sleeping state for more than the wait_timeout or interactive_timeout without providing any requests.
- The program you are running shuts down abruptly in the middle of the transfer.
- In addition to this, when you use the wrong password.
- Lastly, when a server takes more than a connect_timeout seconds to make a connection with the package.
7. The Table-Full Error
This error takes place when the disk you are using for MySQL is full, or the table in which you are inserting the new values has reached its maximum limit. The maximum size of the MySQL database is dependent on operating system constraints. You need to know that MySQL doesn’t have any internal limits for the size of the table. To resolve this error, you first need to look for the partition to ensure that it is not full and causing the error in the first place. If disk space is not the problem, check the variable innob_data_file_path to see if the maximum table size has been defined.
8. Commands Out of Sync
When this error occurs in your MySQL it means that you have done something when calling out the client functions, but in most cases, it is the wrong order of the functions. MySQL works by communicating with the client using the half-duplex response system. Thus, when you type in the query to be sent to the server, the server will force the result to be sent to you. When this happens, you need to execute the mysql_use_result() or mysql_store_result() to retrieve the result which the server is sending. This will lead to a complete query interaction, so you will not face this error. But if you submit a query to the server and then don’t call back results, the error will arise again.
On the other hand, some queries don’t have any result to return. In such queries, you can use mysql_rows(_pstMql). This query will send you the number of records that are updated by your query.
As a MySQL user, one thing you need to know about the program is that when you are working with multi-threading. It becomes necessary for you to ensure that each of the threads has its own independent Mysql to access the database. If you don’t follow this working style, one of your threads might not be able to save the result set, and before the results are saved, the second thread will initiate a new query to the database. Thus, resulting in the commands going out of sync.
9. Table Name is Not Valid
A lot of people confuse this error with the deletion of their database from the server or deletion of their table from the server. There could be a bunch of reasons why you are getting this error. You might have entered the wrong table name, or you are referring to your table incorrectly. As a programmer, you need to know that MySQL server works by using directories and files to store the database tables. This function depends on the operating system file management. Also, the name you are using for the table can be case-sensitive, so make sure you checked the name of the table properly.
If there was no issue with the name, you should restart the MySQL server, as sometimes this error is displayed due to improper server shutdown. If the problem persists, you need to repair the table in your database by using the following command:
repair table Table_name;
On the other hand, you can try restoring the backup which you have created for your database and run that backup table. If all these methods are of no help to you, then you need to copy your ibdata file, which is present in the backup, and enable the InnoDB crash recovery. Beware, before you start the last-mentioned procedure, you must have a good backup of all your database files.
10. Host_name is Blocked
The main reason for this error to occur is when there are too many connection requests from your side which are interrupted in between. You can change the maximum number of variables that are acceptable for successive interrupted connection requests. Once there are max_connect_errors numbers bypass, the server will assume that something is wrong from your end. Thus, it will block your connections until you run the FLUSH HOSTS. This query will take out the connection records which were stored in the MySQL server. The default for mysqld server max_connect_errors is 100 errors. You can adjust them by using the following query:
> mysqld_safe –max_connect_errors=10000
Before you make any changes in the server settings, make sure to check if something is wrong with your TCP/IP connections because it is pretty hard for a user to make an error 100 times in a short duration. If there is a problem with your network, then increasing the max_connect_errors won’t help you solve the error.
Conclusion
A database error could quickly halt your normal working, and it can also dampen your website’s stability if the problem stays for too long. With this quick guide, you will be able to handle the common MySQL errors in no time and get your database back to working correctly.
The database is an integral part of any online web service. Keeping its downtime to a minimum has to be the top priority of web developers and site owners. We hope this article helped you in solving the problem which you were facing in your MySQL. The solutions and ways around that we have provided above can even be performed by a non-technical person. If the errors still exist in your database, then without wasting any time, you must call an expert and get things sorted quickly.