In Redis, the SDIFF command returns the members of the set resulting from the difference between the first set and all the successive sets. In other words, it returns all members of the first set that aren’t in any of the successive sets.
NoSQL
How to Return the Expiry Time as a Unix Timestamp in Redis
In Redis, we have several options for returning the expiry time of a key. One option from Redis 7.0.0 and above is to return it as a Unix timestamp.
When returning the expiry as a Unix timestamp, we can have it returned in seconds or milliseconds. To return it in seconds, we can use the EXPIRETIME command. To return it in milliseconds, we can use the PEXPIRETIME command.
2 Ways to Set a Redis Key Only When it Doesn’t Already Exist
In Redis, it’s possible to set a key only if it doesn’t already exist. As with most things, there’s more than one way to do this.
How to Set an Expiry Only When the New Expiry is Greater Than the Existing Expiry in Redis
Redis SCARD Command Explained
In Redis, the SCARD command returns the number of members in the specified set. This is referred to as the cardinality of the set.
Redis SADD Command Explained
In Redis, the SADD command allows us to add members to a key. We can add multiple members if required.
A Redis set is an unordered collection of unique strings (members).
6 Ways to Set a String in Redis
When working with Redis, we have a number of options for setting keys that store string values.
Here are six ways to set a string value in Redis.
2 Ways to Remove a Key’s Expiry in Redis
A Redis key can have an optional timeout, which makes the key expire after a certain amount of time, or at a certain time. We can use a couple of methods to remove any timeout associated with a key.
Here are two ways to remove a key’s expiry in Redis.
How to Update a Key and Return its Old Value in a Single Operation in Redis
When using the SET command to set a key in Redis, we can use the GET option to return its old value. This allows us to update the value of a key while returning the value that we’re replacing it with.
Note that this option was introduced in Redis 7.0.0, so if it doesn’t work, check your Redis version. If using an earlier version, try the GETSET command instead (which is deprecated from Redis version 6.2.0).
Redis OBJECT IDLETIME Command Explained
In Redis, we can use the OBECT IDLETIME command to check how many seconds has passed since the last access to a given key.