Redis间隔时间即过期（redis隔一会就超时）
Redis is an open source, high-speed, in-memory database that provides a wide variety of data structures and data types. It’s a key-value store, and a popular choice for web applications that need high performance and scalability. One of its most useful features is the ability to set an expiration date for each key, so that the data will automatically expire after a certn amount of time. This feature is known as expiration time, or TTL (Time to Live).
In Redis, the default TTL (Time to Live) is set to zero, which means that the key will never expire. To set an expiration time for a key, you must use the EXPIRE command. This command sets the time-to-live for the key and is measured in seconds. For example, to set a TTL of 60 seconds for the key “my_key”, you can use the following command:
EXPIRE my_key 60
Once the TTL expires, the key and its associated value will be deleted from the database. This feature is useful if you want to create a record that will automatically expire after a certn amount of time. For example, you could use this feature to keep track of user sessions. You could set the expiration to a certn amount of time, such as 30 minutes, and the session will automatically be deleted after that time.
Another useful feature is the PEXPIRE command, which allows you to set an expiration time in milliseconds. If you want to set an expiration of 30 minutes, you can use the following command:
PEXPIRE my_key 1800000
You can also check the expiration time of a key with the TTL and PTTL commands. The TTL command returns the time-to-live of a key in seconds, while the PTTL command returns the time-to-live in milliseconds. For example, to check the expiration time of the key “my_key”, you can use the following command:
TTL my_key
Redis’ expiration time feature is an incredibly useful tool for web applications, allowing developers to easily and quickly set keys that will automatically expire after a certn amount of time. This helps keep the database clean, organized, and performant, as keys and their associated values that are no longer needed are automatically deleted to free up space.
