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Command: Set

Allows to create or update a key/value in a persistent durable way.

set `services/email/instance-3` '{"ip": "10.1.1.22", "port": 9090}'
r0 set 9ms

set `services/email/instance-3` '{"ip": "10.1.1.22", "port": 9090}'
r1 set 12ms

NX​

If the NX modifier is passed the key will be only updated if the key doesn't exist.

set session_user1 "ab10a9bc1924cd" nx
r0 not set 10ms

XX​

If the XX modifier is passed the key will be only updated if the key already exists.

set config_feature_x "enabled" xx
r0 not set 5ms

set config_feature_x "enabled"
r0 set 7ms

set config_feature_x "enabled" xx
r1 set 7ms

EX​

The EX modifier allows to set the key's expiration in milliseconds (a positive integer higher than 0):

set `email/leader` "node3" EX 60000
r0 set 11ms

NOREV​

The NOREV modifier updates the current value without archiving a historical revision row for that write. The key's current revision still advances, latest GET reads still return the new value, and conditional modifiers such as CMP and CMPREV still work.

Use NOREV for cache-style keys or high-churn values where old versions are not useful. It reduces write amplification because Kahuna writes the latest value but skips the extra revision record used by GET ... AT and historical snapshot reads.

set `cache/user/1001` '{"name":"Ada"}' ex 60000 norev
r0 set 8ms

set `cache/user/1001` '{"name":"Ada Lovelace"}' ex 60000 norev
r1 set 7ms

get `cache/user/1001`
r1 {"name":"Ada Lovelace"} 5ms

NOREV can be combined with the other SET modifiers:

set `cache/session/abc` "active" ex 300000 nx norev
r0 set 9ms

set `cache/session/abc` "refreshed" norev cmprev 0
r1 set 8ms

By-revision reads only work for revisions that were archived by normal writes. A revision produced by a NOREV write is not available through GET ... AT <revision>.

Compare-Value-And-Swap (CVAS)​

A Compare-Value-And-Swap (CAS) operation ensures atomic updates and prevents race conditions where multiple clients may try to modify the same key simultaneously:

set `locks/tasks/123` "node1" ex 10000 nx
r0 set 14ms

Mark the task as completed if this node still holds the key:

set `locks/tasks/123` "completed" cmp "node1"
r1 set 9ms

Compare-Revision-And-Swap (CRAS)​

A Compare-Revision-And-Swap (CRAS) does the same as CVAS but the revision is compared:

set `locks/tasks/123` "node1" ex 10000 nx
r7 set 15ms

The prev set returned revision 7. Mark the task as completed if the revision is known by the process:

set `locks/tasks/123` "completed" cmprev 7
r8 set 11ms