In Redis, the RPOP command removes and returns the last elements of the list stored at the specified key.
By default, the command pops a single element from the end of the list. However, we have the option of passing a second argument that specifies how many elements to pop.
Continue readingIn Redis, the BLPOP command is the blocking version of the LPOP command. It blocks the connection when there are no elements to pop from any of the given lists.
The way the command works is that an element is popped from the head of the first list that is non-empty, with the given keys being checked in the order that they are given. When there are no elements to pop from any of the lists, it blocks the connection.
Continue readingIn Redis, the LPOP command removes and returns the first elements of the list stored at the specified key.
By default, the command pops a single element from the beginning of the list. However, we have the option of passing a second argument that specifies how many elements to pop.
Continue readingIn Redis, the RPUSHX command inserts one or more values into the tail of the list at the specified key, but only if the key exists and it contains a list.
If the key doesn’t exist, no operation is performed. If the key exists but it doesn’t contain a list, an error is returned.
Continue readingIn Redis, the RPUSH command inserts one or more values into the tail of the list at the specified key.
If the key doesn’t exist, it is created as an empty list before performing the push operation. If the key already holds a value that is not a list, an error is returned.
Continue readingIn Redis, the LPUSHX command inserts one or more values into the head of the list at the specified key, but only if the key exists and it contains a list.
If the key doesn’t exist, no operation is performed. If the key exists but it doesn’t contain a list, an error is returned.
Continue readingIn Redis, the LPUSH command inserts one or more values into the head of the list at the specified key.
If the key doesn’t exist, it is created as an empty list before performing the push operation. If the key already holds a value that is not a list, an error is returned.
Continue readingMany SQL databases have a SUBSTR() or equivalent function that returns a substring from a specified string.
Redis has a SUBSTR command, but it was deprecated in Redis 2.0.0.
However, Redis also has the GETRANGE command, that basically does the same thing. Basically, anything that was possible with the Redis SUBSTR command, is now possible with the GETRANGE command.
And the GETRANGE command does basically the same thing that most of the SUBSTR() and SUBSTRING() functions do in the SQL world – gets a substring from a string.
In Redis, the OBJECT ENCODING command returns the internal encoding for the Redis object stored at the specified key.
In Redis, the RANDOMKEY command returns a random key from the currently selected database.