MEMORY USAGE

Syntax

MEMORY USAGE key [WITHOUTKEY]

Time complexity: O(1) for strings, O(N) for collection types where N is the number of elements.

ACL categories: @read, @slow

The MEMORY USAGE command reports the number of bytes that the value stored at key requires, including the memory needed to store the key itself.

If the WITHOUTKEY option is given, only the value is accounted for. WITHOUTKEY is Dragonfly-specific.

Dragonfly stores values that are small enough directly inside the key table rather than in a separate allocation. Such values have no allocation of their own, so MEMORY USAGE reports 0 for them.

The SAMPLES option that Redis accepts is not supported. Extra arguments after the key are ignored rather than rejected, so MEMORY USAGE key SAMPLES 0 behaves the same as MEMORY USAGE key.

Return

Integer reply: the number of bytes used by the key and its value.

Null reply: if key does not exist.

Examples

A small string is stored inline and reports no allocation of its own, while a larger one does:

dragonfly> SET tiny abc
OK
dragonfly> MEMORY USAGE tiny
(integer) 0

dragonfly> STRLEN bigstr
(integer) 2000
dragonfly> MEMORY USAGE bigstr
(integer) 1792

Collections account for their elements:

dragonfly> LLEN biglist
(integer) 200
dragonfly> MEMORY USAGE biglist
(integer) 3672

WITHOUTKEY excludes the key itself, which is noticeable with long key names:

dragonfly> MEMORY USAGE kkkkkkkk...kkk
(integer) 3264
dragonfly> MEMORY USAGE kkkkkkkk...kkk WITHOUTKEY
(integer) 3072

A key that does not exist reports nothing:

dragonfly> MEMORY USAGE nosuchkey
(nil)

See also

MEMORY | MEMORY STATS | INFO