Problems of communication with database happen in any system, regardless of whether or not Magento.

So in fact this post helps all developers working with database, more specifically with MySQL.

The SQLSTATE reports a problem, which caused the communication problem. But it does not indicate its origin. Let’s see below.

Interpreting the messages

Usually they are short messages, of type:

SQLSTATE[HY000]: General error: 2013 Lost connection to MySQL server during query

SQLSTATE[HY000]: General error: 2006 MySQL server has gone away

That does not really tell us anything, just what we already know (gave error). A free translation for these messages would be respectively:

Generic error: 2013 I went to consult the database and got lost on the back

Generic error: 2006 The database server abandoned you

And so it is so difficult to find a ready solution, because we do not know the causes of the problem.

Possible causes

Server Out of Service. And this can happen for a few seconds or a few hours. The database server may have restarted or shut down.

And this can occur for several reasons, such as a version upgrade or security, power failure, accidental shutdown, overload, crashes, etc.

Response time. Every system has a wait limit, and when your system “talks” to the database, a request is made… MySQL accepts your request and will process… and this may take some time… if you do not wait long enough, go away without the answer.

That is, there is a setting that tells the server what the execution time for a request is. If the time bursts, the process is interrupted, and an error message is posted to the system.

I do not intend to delve into the subject, but there is also the queue. You want to make a request to the database, but before you there are another 300 people waiting to make the query. And the volume of transactions affects its response time, as well as the overhead mentioned earlier.

Infrastructure

As I said at the beginning of the post, it is difficult to give a definitive solution, because the cause of the problem is unknown and/or uncertain. However, often the deficiency lies in the infrastructure used.

Server and Hosting. A lot of people confuse server and hosting, and it is not possible to give an in-depth explanation at the moment. But in summary:

Server, is the machine, the computer that will stay connected and connected to the internet for people to access your site.

Hosting, it is your configuration within this server, the features that will be available to your system.

Both are important so it is imperative that you hire a quality server with a good hosting plan (VPS, Dedicated, or Cloud).

Recommended Companies: Rackspace, Nexcess, UolHost, Hostgator, Digital Ocean

Configuration

Sometimes you can solve the problem by configuring, at least temporarily (until you run out of resources). Access your MySQL through PhpMyAdmin and click Variables.

All variables can (and should) be configured according to the needs of your system and/or access volume. In the case of Magento you could change the values of:

#default is 10 (seconds), increase if your problem is 2013 error.
connect_timeout=30

#maximum time (seconds) that the server waits before closing a connection without activity.
wait_timeout=300

#25% of available memory for the database is recommended. if it is above 50% the machine is slow
key_buffer_size=64M

#should be double max_connections
table_open_cache=2000

#maximum number of simultaneous connections
max_connections=1000

Official reference: connect_timeout, wait_timeout, key_buffer_size, table_open_cache, max_connections.

Restart mysql after making the changes.

You will not always have access to these settings, especially if you are using a shared hosting plan.

Attention! If you are using a shared plan, problems will recur.

At least now you have an idea of what can be done to solve the problem.

Success!