In Redis, the SETEX command sets a key to hold a given string value, and sets that key to time out after a given number of seconds.

Note: The SET command can do the same thing, and it’s possible that the SETEX command may be deprecated at some point. Therefore, it’s probably a good idea to use SET instead of SETEX if possible.

Syntax

The syntax for SETEX goes like this:

SETEX key seconds value

Where key is the key to set, seconds is the number of seconds before it expires, and value is the value to set.

It’s the equivalent of the following:

SET mykey value
EXPIRE mykey seconds

Which is basically the same as doing this:

SET mykey value EX seconds

Example

Here’s a simple example to demonstrate:

SETEX lunch 30 "Pad Thai"

Result:

OK

Now, if I’m quick and use GET to return the value before the 30 seconds is up, I can see the value:

GET lunch

Result:

"Pad Thai"

But if I wait until after the 30 seconds is up, I get a null result:

GET lunch

Result:

(nil)

As mentioned, we can do the same thing with the SET command, so it’s probably better to use that in case SETEX is deprecated at some point.

There’s also a PSETEX command that does the same thing as SETEX, except that PSETEX uses milliseconds.