MySQL Server has gone away when importing large sq

问题:

I tried to import a large sql file through phpMyAdmin...But it kept showing error

\'MySql server has gone away\'

What to do?

回答1:

As stated here:

Two most common reasons (and fixes) for the MySQL server has gone away (error 2006) are:

Server timed out and closed the connection. How to fix:

1. check that wait_timeout variable in your mysqld’s my.cnf configuration file is large enough. On Debian: sudo nano /etc/mysql/my.cnf, set wait_timeout = 600 seconds (you can tweak/decrease this value when error 2006 is gone), then sudo /etc/init.d/mysql restart. I didn\'t check, but the default value for wait_timeout might be around 28800 seconds (8 hours).

2. Server dropped an incorrect or too large packet. If mysqld gets a packet that is too large or incorrect, it assumes that something has gone wrong with the client and closes the connection. You can increase the maximal packet size limit by increasing the value of max_allowed_packet in my.cnf file. On Debian: sudo nano /etc/mysql/my.cnf, set max_allowed_packet = 64M (you can tweak/decrease this value when error 2006 is gone), then sudo /etc/init.d/mysql restart.

Edit: Notice that MySQL option files do not have their commands already available as comments (like in php.ini for instance). So you must type any change/tweak in my.cnf or my.ini and place them in mysql/data directory or in any of the other paths, under the proper group of options such as [client], [myslqd]...etc, for example :
[mysqld]
wait_timeout = 600
max_allowed_packet = 64M
Then restart the server. To get the their values, type in the console:
select @@wait_timeout;
select @@max_allowed_packet;

回答2:

For me this solution didn\'t work out so I executed

SET GLOBAL max_allowed_packet=1073741824;

in my SQL client.

If not able to change this with MYSql service running, you should stop the service and change the variable in \"my.ini\" file.

For example:

max_allowed_packet=20M

回答3:

If you are running with default values then you have a lot of room to optimize your mysql configuration.

The first step I recommend is to increase the max_allowed_packet to 128M.

Then download the MySQL Tuning Primer script and run it. It will provide recommendations to several facets of your config for better performance.

Also look into adjusting your timeout values both in MySQL and PHP.

How big (file size) is the file you are importing and are you able to import the file using the mysql command line client instead of PHPMyAdmin?

回答4:

If you are working on XAMPP then you can fix the MySQL Server has gone away issue with following changes..

open your my.ini file my.ini location is (D:\\xampp\\mysql\\bin\\my.ini)

change the following variable values

max_allowed_packet = 64M
innodb_lock_wait_timeout = 500

回答5:

If you are using MAMP on OS X, you will need to change the max_allowed_packet value in the template for MySQL.

1. You can find it at: File > Edit template > MySQL my.cnf

2. Then just search for max_allowed_packet, change the value and save.

Hope this helps someone.

回答6:

I solved my issue with this short /etc/mysql/my.cnf file :

[mysqld]
wait_timeout = 600
max_allowed_packet = 100M

回答7:

The other reason this can happen is running out of memory. Check /var/log/messages and make sure that your my.cnf is not set up to cause mysqld to allocate more memory than your machine has.

Your mysqld process can actually be killed by the kernel and then re-started by the \"safe_mysqld\" process without you realizing it.

Use top and watch the memory allocation while it\'s running to see what your headroom is.

make a backup of my.cnf before changing it.

回答8:

I had this error and other related ones, when I imported at 16 GB SQL file. For me, editing my.ini and setting the following (based on several different posts) in the [mysqld] section:

max_allowed_packet      = 110M
innodb_buffer_pool_size=511M
innodb_log_file_size=500M
innodb_log_buffer_size = 800M
net_read_timeout        = 600
net_write_timeout       = 600

If you are running under Windows, go to the control panel, services, and look at the details for MySQL and you will see where my.ini is. Then after you edit and save my.ini, restart the mysql service (or restart the computer).

If you are using HeidiSQL, you can also set some or all of these using that.

回答9:

If your data includes BLOB data:

Note that an import of data from the command line seems to choke on BLOB data, resulting in the \'MySQL server has gone away\' error.

To avoid this, re-create the mysqldump but with the --hex-blob flag:

http://dev.mysql.com/doc/refman/5.7/en/mysqldump.html#option_mysqldump_hex-blob

which will write out the data file with hex values rather than binary amongst other text.

PhpMyAdmin also has the option \"Dump binary columns in hexadecimal notation (for example, \"abc\" becomes 0x616263)\" which works nicely.

Note that there is a long-standing bug (as of December 2015) which means that GEOM columns are not converted: Back up a table with a GEOMETRY column using mysqldump? so using a program like PhpMyAdmin seems to be the only workaround (the option noted above does correctly convert GEOM columns).

回答10:

I updated \"max_allowed_packet\" to 1024M, but it still wasn\'t working. It turns out my deployment script was running:

mysql --max_allowed_packet=512M --database=mydb -u root < .\\db\\db.sql

Be sure to explicitly specify a bigger number from the command line if you are donig it this way.

回答11:

If it takes a long time to fail, then enlarge the wait_timeout variable.

If it fails right away, enlarge the max_allowed_packet variable; it it still doesn\'t work, make sure the command is valid SQL. Mine had unescaped quotes which screwed everything up.

Also, if feasible, consider limiting the number of inserts of a single SQL command to, say, 1000. You can create a script that creates multiple statements out of a single one by reintroducing the INSERT... part every n inserts.

回答12:

i got a similar error.. to solve this just open my.ini file..here at line no 36 change the value of maximum allowed packet size ie. max_allowed_packet = 20M

回答13:

I had similar error today when duplicating database (MySQL server has gone away...), but when I tried to restart mysql.server restart I got error

ERROR! The server quit without updating PID ...

This is how I solved it: I opened up Applications/Utilities/ and ran Activity Monitor

 quit mysqld

then was able to solve the error problem with

mysql.server restart

回答14:

I am doing some large calculations which involves the mysql connection to stay long time and with heavy data. i was facing this \"Mysql go away issue\". So i tried t optimize the queries but that doen\'t helped me then i increased the mysql variables limit which is set to a lower value by default.

wait_timeout max_allowed_packet

To the limit what ever suits to you it should be the Any Number * 1024(Bytes). you can login to terminal using \'mysql -u username - p\' command and can check and change for these variable limits.

回答15:

Make sure mysqld process does not restart because of service managers like systemd.

I had this problem in vagrant with centos 7. Configuration tweaks didn\'t help. Turned out it was systemd which killed mysqld service every time when it took too much memory.

回答16:

If increasing max_allowed_packet doesn\'t help.

I was getting the same error as you when importing a .sql file into my database via Sequel Pro.

The error still persisted after upping the max_allowed_packet to 512M so I ran the import in the command line instead with:

mysql --verbose -u root -p DatabaseName < MySQL.sql

It gave the following error:

ASCII \'\\0\' appeared in the statement, but this is not allowed unless option --binary-mode is enabled

I found a couple helpful StackOverflow questions:

• Enable binary mode while restoring a Database from an SQL dump
• Mysql ERROR: ASCII '\\0' while importing sql file on linux server

In my case, my .sql file was a little corrupt or something. The MySQL dump we get comes in two zip files that need to be concatenated together and then unzipped. I think the unzipping was interrupted initially, leaving the file with some odd characters and encodings. Getting a fresh MySQL dump and unzipping it properly worked for me.

Just wanted to add this here in case others find that increasing the max_allowed_packet variable was not helping.

回答17:

For GoDaddy shared hosting

On GoDaddy shared hosting accounts, it is tricky to tweak the PHP.ini etc files. However, there is another way and it just worked perfectly for me. (I just successfully uploaded a 3.8Mb .sql text file, containing 3100 rows and 145 cols. Using the IMPORT command in phpMyAdmin, I was getting the dreaded MySQL server has gone away error, and no further information.)

I found that Matt Butcher had the right answer. Like Matt, I had tried all kinds of tricks, from exporting MySQL databases in bite-sized chunks, to writing scripts that break large imports into smaller ones. But here is what worked:

(1) CPANEL ---> FILES (group) ---> BACKUP

(2a) Under \"Partial Backups\" heading...
(2b) Under \"Download a MySQL Database Backup\"
(2c) Choose your database and download a backup (this step optional, but wise)

(3a) Directly to the right of 2b, under heading \"Restore a MySQL Database Backup\"
(3b) Choose the .SQL import file from your local drive
(3c) True happiness will be yours (shortly....) Mine took about 5 seconds

I was able to use this method to import a single table. Nothing else in my database was affected -- but that is what step (2) above is intended to protect against.

Notes:
a. If you are unsure how to create a .SQL import file, use phpMyAdmin to export a table and modify that file structure.

SOURCE: Matt Butcher 2010 Article