Have you just got client_error bad data chunk while adding a key in Memcached?

Memcached is a memory caching system, but the improper entry of data can end up in errors.

At Bobcares, we get many queries on Memcached, as a part of our Server Management Services.

Today, let’s see why this error occurs. We’ll also see how our Support Engineers avoid this error while updating data in Memcached.

A quick look on Memcached

Memcached is an open-source memory caching system. We use it to speed up dynamic web applications by reducing the database load. That is Memcached loads data from the cache to speed up websites.

At the same time, it updates itself from the connected database if the fetched data is not available. The Memcached server is a big hash table suitable for websites with high database load.

One way to connect to the Memcached server is by using the telnet command. And the command usage is,

telnet <HOST> <PORT>

This connects to the Memcached server where we can store and retrieve data. But some users end up in the error CLIENT_ERROR bad data chunk while managing data in the server. This is mainly due to improper entry of the data.

Let’s have a closer look at this error.

When does Memcached show client_error bad data chunk?

The Memcached provides many data storage command like, set, add, replace, append, and so on. And the usage of storage command is

<command> key flags exptime bytes [noreply]

In the next line, we have to enter the value corresponding to the key. Then using retrieval command ‘get‘ we can retrieve the data. Its usage is,

get key_name

This outputs the value corresponding to the key along with the flag and the bytes. The output appears as,

VALUE key_name flag bytes
<Value>
END

But the incorrect entry of key name and value often end up in errors.

Why does Memcached show client_error bad data chunk?

Let’s see an instance when one of our customers got this error. The customer’s command usage was as,

The error occurred because the user didn’t specify the value. So while he tried to access the key, it returned this error as there was no value associated with the key. Because a key is a text string that uniquely identifies the data, which value.

There are other factors that lead to this error. This includes white space and control characters in the key name. So whenever customers approach us with this error our Support Engineers check the correctness of the key value and fix them.

[Need assistance in setting up Memcached? – We can help you.]

Conclusion

In short, Memcached returns client_error bad data chunk when a user add improper key. This can also show up if there is no value for a corresponding key. Today we saw how our Support Engineers avoid this error.