Get Redis key's memory usage

[Dinesh Joshi]

Given a key, I'm looking to get back the memory utilization of the key. Is there a redis command that'll allow me to get this statistic? This is important to analyze the memory consumption on the key level. I see there are rdb analysis tools that allow me to do something similar however, I'd like to do it in an online manner where I could query the redis server for this info.

[Marc Gravell]

I'm not at a PC, but IIRC "debug object {key}" returns the "serializedlength". This is, however, entirely undocumented and unsupported - and I don't even know if what it returns can be translated into regular memory usage etc. Another option could be "dump {key}" and measure it - ideally via lua so you don't pay for the bandwidth.

Marc

On 23 Nov 2014 21:07, "Dinesh Joshi" <dinesh....@gmail.com> wrote:

Given a key, I'm looking to get back the memory utilization of the key. Is there a redis command that'll allow me to get this statistic? This is important to analyze the memory consumption on the key level. I see there are rdb analysis tools that allow me to do something similar however, I'd like to do it in an online manner where I could query the redis server for this info.

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[Josiah Carlson]

The serializedlength field is how large the data would be if it was part of a snapshot or was DUMPed. You can save yourself some memory allocation by sticking with DEBUG OBJECT.

In terms of actual memory used, no, there currently isn't a function to do so.

 - Josiah

[Sripathi Krishnan]

I see there are rdb analysis tools that allow me to do something similar however, I'd like to do it in an online manner where I could query the redis server for this info.

rdb does allow you to do it in an online manner. Run this command - 

redis-memory-for-key -s localhost -p 6379 -a mypassword person:1 

It connects to the redis server using the provided credentials, does a dump on the specified key, and then estimates the memory. See https://github.com/sripathikrishnan/redis-rdb-tools/blob/master/rdbtools/cli/redis_memory_for_key.py#L43

--Sri

[Dinesh Joshi]

Thank you all for the input.