The slowlog command on Azure redis returns the following item in response. What does this command do? It doesn't seem to be a command triggered from the client.
1) (integer) 260
2) (integer) 1660587982
3) (integer) 15508
4) 1) "ManagementCommand"
2) "list"
5) "[::]:31729"
6) ""
ManagementCommand are commands that are triggered by data plane components owned by Azure Cache for Redis for health monitoring purposes there are some Redis commands that return info about the cache itself. The slowlog is an example of this.
I am facing a quite strange issue in our deployment
After certain time in operation
I could not add a particular list with a particular keyname or listname to Redis using RPUSH.
Example
RPUSH client-send-process-servername TEST
I am unable to add that key to Redis database.
Anyways the output after executing that command i get
(Integer) 1
But i could not see the list
redis-cli keys *client-send*
Return empty list
However when this problem appears
I am able successfully execute the following command.
RPUSH client-send-process-ser TEST
And
redis-cli keys *client-send*
NOTE: one ASTRICK before n aftet client-send string
Which is not displayed here
It is listing the Queue
"client-send-process-ser"
However strangely i could not add a List with specific key say
client-send-process-servername
Any ideas to debug further.. where to look and what to look.
Redis Server Version is 2.8
I tired enabling debug logs in redis and tried to use redis-monitor command.
However nothing relevant could be found explaining this issue. I am eager to find a solution. Please if some one could help me to pursue further would be a great help.
It seems that this problem is not reproducible. However I've tested it in my local pc and found that it is working fine.
Example:
➜ ~ redis-cli
127.0.0.1:6379> RPUSH client-send-process-servername TEST
(integer) 1
127.0.0.1:6379> keys *client-send*
1) "client-send-process-servername"
127.0.0.1:6379> keys client-send*
1) "client-send-process-servername"
127.0.0.1:6379> RPUSH client-send-process-ser TEST
(integer) 1
127.0.0.1:6379> keys client-send*
1) "client-send-process-ser"
2) "client-send-process-servername"
127.0.0.1:6379>
If there is any option, you can try updating your redis server. current updated versions is 5.0.7 and yours is 2.8.
I'm new to Redis. How can I get the memory footprint of a specific key in redis?
db0
1) "unacked_mutex"
2) "_kombu.binding.celery"
3) "_kombu.binding.celery.pidbox"
4) "_kombu.binding.celeryev"
I just want to get the memory footprint of one specific key like "_kombu.binding.celery" , or one specific db like db0 , how can I get it?
redis_version: 2.8.17
Any commentary is very welcome. great thanks.
You are running a very old version of redis. The MEMORY command is not available in that version, so there is no precise way of getting at this information. However, you can approximate this information using the DUMP command.
Simply call DUMP _kombu.binding.celery and save the results to a file. The result is some characters and escape sequences. When you load this file into an environment like node, you can look at the length of the string and multiply by 2 to get the number of bytes. This is not precise, but it will give you a generally close approximation.
Here's what you could do:
in Redis:
$ redis-cli
127.0.0.1:6379> hset c 123 456
(integer) 0
127.0.0.1:6379> dump c
"\r\x12\x12\x00\x00\x00\r\x00\x00\x00\x02\x00\x00\xfe{\x03\xc0\xc8\x01\xff\t\x00\x10\xd4L \x908\x8b2"
in Node:
$ node
> a="\r\x12\x12\x00\x00\x00\r\x00\x00\x00\x02\x00\x00\xfe{\x03\xc0\xc8\x01\xff\t\x00\x10\xd4L \x908\x8b2"
'\r\u0012\u0012\u0000\u0000\u0000\r\u0000\u0000\u0000\u0002\u0000\u0000þ{\u0003ÀÈ\u0001ÿ\t\u0000\u0010ÔL 82'
> a.length
30
This is close to half of the actual amount that redis provides with MEMORY USAGE:
127.0.0.1:6379> MEMORY USAGE c
(integer) 63
MEMORY USAGE _kombu.binding.celery would give you the number of bytes that a key and value require to be stored in RAM.
Here is the doc for the command.
I am storing ~300M objects in a redis database. The object consist of :
an ID
a date
an array of 48 values
I use the ID/date as a key and I am looking for the optimal way (memory usage) of storing the 48 values.
The value are integers and will usually be between [1-1000].
The first way I used consisted in building in object in Java and use a framework (spring-data-redis) which automatically serializes the object.
The resulting format is something like :
{\"#class\":\"com.mycompany.Points\",\"faceId\":1234,\"date\":[\"java.util.Date\",1509663600000],\"points\":[5,5,10,10,10,10,60,60,60,60,60,60,40,40,40,40,40,40,30,30,30,30,30,80,80,80,80,80,80,80,20,20,20,20,20,10,10,10,10,10,5,5,5,5,5,5,5,5]}
I then used this command to track the size of this object in redis :
redis 127.0.0.1:6379> DEBUG OBJECT POINTS_215004#03-11-2017
Value at:0x7fce4b2b6ac0 refcount:1 encoding:raw serializedlength:206 lru:2074768 lru_seconds_idle:10
So if I read it correctly, the entry takes 206 (206 what?) in the database.
I tried to store it as a list :
redis 127.0.0.1:6379> lpush dummy 1 2 3 4 5 [...] 48
(integer) 48
And actually, the size was almost the same:
redis 127.0.0.1:6379> DEBUG OBJECT dummy
Value at:0x7fce467c2800 refcount:1 encoding:ziplist serializedlength:205 lru:2074809 lru_seconds_idle:10
Maybe the type ziplist is more memory consuming.
Then I tried to store it as a plain string :
redis 127.0.0.1:6379> set dummy [5,5,10,10,10,10,60,60,60,60,60,60,40,40,40,40,40,40,30,30,30,30,30,80,80,80,80,80,80,80,20,20,20,20,20,10,10,10,10,10,5,5,5,5,5,5,5,5]
The size decreased to 53 :
redis 127.0.0.1:6379> debug object dummy
Value at:0x7fce470b2dc0 refcount:1 encoding:raw serializedlength:53 lru:2074818 lru_seconds_idle:10
It there a more apprioriate way to store this array?
It there a more apprioriate way to store this array?
This depends on your version of Redis, but as of v3.2 there's the incredible BITFIELD, that is just the thing for you if you use it with unsigned 10-bit fields (the closest power of two to 1000).
Note: DEBUG OBJECT's output is not a reliable way to measure the memory consumption of a key in Redis - the serializedlength field is given in bytes needed for persisting the object, not the actual footprint in memory that includes various administrative overheads on top of the data itself. As of v4 we have the MEMORY USAGE command that does a much better job - see https://github.com/antirez/redis-doc/pull/851 for the doc details.
$ for i in {0..47}; do redis-cli BITFIELD dummy SET u10 \#$i $i; done
...
$ redis-cli
127.0.0.1:6379> strlen dummy
(integer) 60
127.0.0.1:6379> DEBUG OBJECT dummy
Value at:0x7f83e040e430 refcount:1 encoding:raw serializedlength:61 lru:16563203 lru_seconds_idle:27
127.0.0.1:6379> MEMORY USAGE dummy
(integer) 117
For earlier versions of Redis, you can explore the use of Lua scripting and compose a script-based variant of the same logic and/or attempt using MessagePack encoding of the array.
I have a string type key value store in redis having keys like this--
/url-pattern/url-slug-1
/url-pattern/url-slug-2
/url-pattern/url-slug-3
/url-pattern/url-slug-4 ...
I can retrieve all the keys of /url-pattern/ using a wild card query like this --
keys /url-pattern/*
I would like to retrieve the values of all keys corresponding to this wildcard /url-pattern/*
I tried this
mget /url-pattern/*
1) (nil)
but it doesnt returned the array as expected.
How can I retrieve the values of all keys corresponding to /url-pattern/*
I also want to do a sum on the values, but I think there is no such thing called SUM() in redis
MGET accepts multiple arguments where each a key name. It does not do key name patterns.
What you could do is first fetch all the relevant key names (do not use KEYS, use SCAN instead) and then fetch their values with an MGET.
Here is an updated answer for 2015.
If you can upgrade Redis above 2.8, the SCAN command with MATCH will work for this. Before that version, not so much, and do NOT use the KEYS command except in a development environment.
http://redis.io/commands/scan
Example on command line:
$ redis-cli
127.0.0.1:6379> scan match V3.0:*
(error) ERR invalid cursor
127.0.0.1:6379> scan 0 match V3.0:*
1) "0"
2) 1) "V3.0:UNITTEST55660BC7E0C5B"
2) "V3.0:shop.domain.com:route"
3) "V3.0:UNITTEST55660BC4A2548"
127.0.0.1:6379> scan 0 match V1.0:*
1) "0"
2) (empty list or set)
127.0.0.1:6379> scan 0 match V3.0:*
1) "0"
2) 1) "V3.0:UNITTEST55660BC7E0C5B"
2) "V3.0:shop.domain.com:route"
3) "V3.0:UNITTEST55660BC4A2548"
Example in PHP:
// Initialize our iterator to NULL
$iterate = null;
// retry when we get no keys back
$redis->setOption(Redis::OPT_SCAN, Redis::SCAN_RETRY);
while ($arr_keys = $redis->scan($iterate, 'match:*')) {
foreach ($arr_keys as $str_key) {
echo "Here is a key: $str_key\n";
}
echo "No more keys to scan!\n";
}
Note, php code is not tested and from the core documentation for example here. Production code would need to be modified depending on the keys needed to look up.
For those on Ubuntu here are the instructions to upgrade php5-redis:
Download the 2.2.7 package here: http://pecl.php.net/package/redis
$ php -i | grep Redis
Redis Support => enabled
Redis Version => 2.2.4
Follow instructions in README to phpize, configure, make install
Create a symlink for command line cli package: cd /etc/php5/cli/conf.d && sudo ln -s ../../mods-available/redis.ini 20-redis.ini
$ php -i | grep Redis
Redis Support => enabled
Redis Version => 2.2.7
There is NO command available in REDIS which can return values from wildcard keys.
If you see the documentation for KEYS command: http://redis.io/commands/keys, it says
Consider KEYS as a command that should only be used in production
environments with extreme care. It may ruin performance when it is
executed against large databases. This command is intended for
debugging and special operations. Don't use KEYS in your regular
application code.
I don't know your business use case, but looks like you may have to use different data structure for this requirement. You can use list or set to store similar url patterns.