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I am new to redis, I do not know the meaning of "keyspace" and "key space" in redis terminology which I encountered in redis official website. Can someone help me to clear that? Thanks.
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A key-value database (sometimes called a key-value store) uses a simple key-value method to store data. These databases contain a simple string (the key) that is always unique and an arbitrary large data field (the value). They are easy to design and implement.
The first command you can use to get the total number of keys in a Redis database is the DBSIZE command. This simple command should return the total number of keys in a selected database as an integer value. The above example command shows that there are 203 keys in the database at index 10.
The Redis KEYS command returns all the keys in the database that match a pattern (or all the keys in the key space). Similar commands for fetching all the fields stored in a hash is HGETALL and for all fetching the members of a SMEMBERS. The keys in Redis themselves are stored in a dictionary (aka a hash table).
Discover BigKeys by using the BigKeys parameter in redis-cli If you do not have a clear target key for analysis but want to find out the BigKey in Redis, you can use redis-cli to achieve this goal by adding '--BigKeys' in the end.
The keyspace notifications in Redis are used to track the real-time changes to Redis keys and values. Users can subscribe to Pub/Sub channels in Keyspace notifications to receive events that affect the Redis data set somehow. The following are some examples of events that can be received: An RPUSH operation is performed on all keys.
When you set a key, redis will publish a pub sub message (point number 1), with a kind of “channel” point number 3 (with mykey is the key that is being changed, i guess 0 is the redis default DB?), in which we got since we listened to __key*__:* (subscribe pattern), and point number 4 is the command happened to that key, which is set.
IMPORTANT Keyspace notifications is a feature available since 2.8.0 Keyspace notifications allow clients to subscribe… Here are the steps to “use this feature”: Enable the redis notification in redis.conf / using CONFIG SET command Create a subscribe redis connection using determined key pattern
All the keys expiring in the database 0. Note: Redis Pub/Sub is fire and forget that is, if your Pub/Sub client disconnects, and reconnects later, all the events delivered during the time the client was disconnected are lost.
These terms refer to the internal dictionary that Redis manages, in which all keys are stored. The keyspace of a Redis database is managed by a single server in the case of a single instance deployment, and is divided to exclusive slot ranges managed by different nodes when using cluster mode.
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