The Redis EXPIRE command sets a timeout on a given key in seconds. After the timeout has expired, the key will be deleted.
Redis also has a PEXPIRE command that works the same as EXPIRE, except that it returns the timeout in milliseconds instead of seconds.
A key with a timeout is said to be volatile in Redis terminology.
In Redis, the STRLEN command returns the length of the string stored at a given key.
The Redis PSETEX command sets a key to hold a given string value, and sets that key to time out after a given number of milliseconds.
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.
The Redis GETDEL command gets the value of a given key, then deletes that key. It’s similar to the GET command, except that it deletes the key on success (the GET command doesn’t delete the key – it only returns its value).
An error is returned if the value stored at key is not a string.
The GETDEL command was introduced in Redis 6.2.0.
In Redis, the DEL command removes one or more keys. If a specified key doesn’t exist, it’s ignored.
In Redis, the LCS command implements the longest common subsequence algorithm.
The longest common subsequence algorithm finds the longest subsequence common to all sequences in a set of sequences. Note that this is different to the longest common string algorithm (also known as the longest common substring algorithm), which requires that matching characters in the string are contiguous. The longest common subsequence algorithm, on the other hand, doesn’t require matching characters to be contiguous.
The LCS command was introduced in Redis 7.0.0.
The Redis GETEX command enables us to get the value of a key, then set the key’s expiration. We can also use it to remove any existing expiration associated with the key.
In MariaDB, the NVL2() function allows us to replace a value with another value, the new value being determined by whether or not the initial value is null.
It’s similar to the NVL() function, except that NVL2() accepts three arguments instead of two. This allows us to specify a different value to return in the event the first argument is not null.