MEMORY USAGE

MEMORY USAGE key [SAMPLES count]

Available since:

Redis CE 4.0.0

Time complexity:

O(N) where N is the number of samples.

ACL categories:

@read, @slow,

The MEMORY USAGE command reports the number of bytes that a key and its value require to be stored in RAM.

The reported usage is the total of memory allocations for data and administrative overheads that a key and its value require.

For nested data types, the optional SAMPLES option can be provided, where count is the number of sampled nested values. The samples are averaged to estimate the total size. By default, this option is set to 5. To sample the all of the nested values, use SAMPLES 0.

Examples

With Redis v7.2.0 64-bit and jemalloc, the empty string measures as follows:

> SET "" ""
OK
> MEMORY USAGE ""
(integer) 56

These bytes are pure overhead at the moment as no actual data is stored, and are used for maintaining the internal data structures of the server (include internal allocator fragmentation). Longer keys and values show asymptotically linear usage.

> SET foo bar
OK
> MEMORY USAGE foo
(integer) 56
> SET foo2 mybar
OK
> MEMORY USAGE foo2
(integer) 64
> SET foo3 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789
OK
> MEMORY USAGE foo3
(integer) 160

Redis Software and Redis Cloud compatibility

Note: key memory usage is different on Redis Software or Redis Cloud active-active databases than on non-active-active databases. This is because memory usage includes some amount of CRDB overhead.

RESP2 Reply

One of the following:

• Integer reply: the memory usage in bytes.
• Nil reply: if the key does not exist.

RESP3 Reply

One of the following:

• Integer reply: the memory usage in bytes.
• Null reply: if the key does not exist.