Redis Show database size size for keys

Question

My redis instance seems to being growing very large and I d like to find out which of the multiple databases I have in there consumes how much memory  Redis  INFO command just shows me the total size and the number of keys per database which doesn t give me much insight    So any tools ideas that give me more information when monitoring the redis server would be appreciated   The Redis documentation doesn t show me any commands that can return the consumed memory of certain keys  so I guess if any buggy code would write a lot of  trash  to redis this could be really hard to find

User · Answer

Take a look at this project it outputs some interesting stats about keyspaces based on regexs and prefixes. It uses the DEBUG OBJECT command and scans the db, identifying groups of keys and estimating the percentage of space they're taking up.

https://github.com/snmaynard/redis-audit

Output looks like this:

Summary  

---------------------------------------------------+--------------+-------------------+---------------------------------------------------  
Key                                                | Memory Usage | Expiry Proportion | Last Access Time                                    
---------------------------------------------------+--------------+-------------------+---------------------------------------------------  
notification_3109439                               | 88.14%       | 0.0%              | 2 minutes                               
user_profile_3897016                               | 11.86%       | 99.98%            | 20 seconds  
---------------------------------------------------+--------------+-------------------+---------------------------------------------------

Or this this one: https://github.com/sripathikrishnan/redis-rdb-tools which does a full analysis on the entire keyspace by analyzing a dump.rdb file offline. This one works well also. It can give you the avg/min/max size for the entries in your db, and will even do it based on a prefix.

User · Answer

The solution from the comments deserves it s own answer   redis-cli --bigkeys

User · Answer

So my solution to my own problem  After playing around with redis-cli a bit longer I found out that DEBUG OBJECT  lt key gt  reveals something like the serializedlength of key  which was in fact something I was looking for     For a whole database you need to aggregate all values for KEYS   which shouldn t be too difficult with a scripting language of your choice     The bad thing is that redis io doesn t really have a lot of information about DEBUG OBJECT

User · Answer

I usually prefer the key sampling method to troubleshoot such scenarios      redis-cli -p 6379 -n db number --bigkeys   Eg -      redis-cli -p 6370 -n 0 --bigkeys

User · Answer

Perhaps you can do some introspection on the db file  The protocol is relatively simple  yet not well documented   so you could write a parser for it to determine which individual keys are taking up a lot of space     New suggestions   Have you tried using MONITOR to see what is being written  live  Perhaps you can find the issue with the data in motion

User · Answer

How about redis-cli get KEYNAME   wc -c

User · Answer

You might find it very useful to sample Redis keys and group them by type  Salvatore has written a tool called redis-sampler that issues about 10000 RANDOMKEY commands followed by a TYPE on retrieved keys  In a matter of seconds  or minutes  you should get a fairly accurate view of the distribution of key types   I ve written an extension  unfortunately not anywhere open-source because it s work related   that adds a bit of introspection of key names via regexs that give you an idea of what kinds of application keys  according to whatever naming structure you re using   are stored in Redis  Combined with the more general output of redis-sampler  this should give you an extremely good idea of what s going on

User · Answer

You can use  net application https   github com abhiyx RedisSizeCalculator to calculate the size of redis key   Please feel free to give your feedback for the same

User · Answer

MEMORY USAGE key command gives you 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 its value require  source redis documentation

[redis] Redis: Show database size/size for keys

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