READONLY
Syntax
READONLY
Time complexity: O(1)
ACL categories: @connection, @fast
In Valkey, READONLY lets a connection to a cluster replica read the keys of the replica's shard
instead of being redirected to the master.
Dragonfly accepts READONLY so that cluster clients can send it, but the command does nothing:
it always replies OK and does not change the connection.
This is the case in every mode, including when cluster mode is off.
Dragonfly replicas serve reads without READONLY:
- With
--cluster_mode=yes, a replica that the cluster configuration lists in a shard serves reads of that shard's slots on every connection. Keys of other slots get aMOVEDredirection. - With
--cluster_mode=emulated, or with cluster mode off, a replica serves reads of all keys.
Writes to a replica fail with READONLY You can't write against a read only replica.,
whether or not the connection sent READONLY.
READWRITE does not change the connection either.
Return
Simple string reply: OK.
Examples
dragonfly> READONLY
OK
A replica of a cluster of nodes started with --cluster_mode=yes.
The key user:1000 (slot 1649) belongs to the replica's shard, and its master set it to alice.
The replica serves the read without READONLY and rejects the write after it:
dragonfly> GET user:1000
"alice"
dragonfly> READONLY
OK
dragonfly> SET user:1000 bob
(error) READONLY You can't write against a read only replica.