How many keys can store in an Aerospike instance?
The Aerospike community version has the same limit as the Redis, 4,294,967,296 records can store in a single node and single namespace of Aerospike.
Full list of limits are here
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I have a redis standalone server, with around 8000 keys at a given instance .
The used_memeory is showing to be around 8.5 GB.
My individuals key-value size is max around 50kb , by that calculation the used_memory should be less than 1 GB (50kb * 8000)
I am using spring RedisTemplate with default pool configuration to connect to redis
Any idea what should I look into, to narrow down where the memory is being consumed ?
zset internally uses two data structures to hold the same elements in order to get O(log(N)) INSERT and REMOVE operations into a sorted data structure.
The two Data-structures to be specific are,
Hash Table
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Storage for ideal cases according to my research is in the following order,
hset < set < zset
I would recommend you to start using hset in case you have hierarchical data storage. This would lower down your memory consumption but might make searching teeny-tiny bit slower (only if one key has more than say a couple of hundred records)
I am new to redis, I do not know the meaning of "keyspace" and "key space" in redis terminology which I encountered in redis official website. Can someone help me to clear that? Thanks.
These terms refer to the internal dictionary that Redis manages, in which all keys are stored. The keyspace of a Redis database is managed by a single server in the case of a single instance deployment, and is divided to exclusive slot ranges managed by different nodes when using cluster mode.
In a key-value database, all keys can be in one node or divided in multiple nodes. Suppose I am storing telephone dictionary as key-value store with name as key and phone number as a value. If I store names A-L on one node and M-Z on another node, I divide my database into two key spaces. When I run query to search number of Smith, I need to search only second key space or node. This divides the query on multiple nodes and divide the work giving faster result. This could be shared-nothing model of working.
Having grown out of Redis for some data structures I'm looking to other solutions with good disk/SSD performance. I recently discovered Aerospike which seems to excel in an SSD environment.
One of the most memory hungry structures are about 100.000 Redis sets, which can each contain up to 10.000 strings. Each string is between 10 and 30 characters.
These sets are mostly used for exists / uniqueness checks.
What would be the best way to model these? I generally see 2 options:
* model a redis set as an Aerospike lset
* model each value in a set separately.
Besides this choice, the 100.000 Redis sets are used as a partitioning on the keys. For reasons of locality it would probably make sense to have a similar sort of partitioning/namespacing in Aerospike. However, I'm pretty sure the notion of 'namespacing' in Aerospike isn't used for this sort of key partitioning. What would be a correct way (if any) to do this in Aerospike, or is that not needed?
Aerospike does its own partitioning for load balancing and high availability needs. Namespace is synonymous to Database in traditional sense and NOT to Partition of data. Data in a Namespace is partitioned and stored in cluster. You as a user need not worry about placement of the data.
I would map a Redis set to Aerospike "lset" (one to one). Aerospike should takes care of data locality for the data in a given "lset".
Yes, you should not be worrying about the locality of the data as Aerospike does auto-sharding. This ensures equal balancing of data distribution and read/write load across all nodes of the cluster.
Putting in lset has its advantages. It gives functionality similar to redis where you do not need to write your own functionality. But at the same time it has its disadvantes too. So, you should choose based on your requirements. All the operations on a single set will be serialized. So, if you are expecting the read/wirte to the set to be parallelised, lset may not be the right fit for you. Also, the exists check in lset will actually read the full record and return true false. Aerospike has an exists api for normal keys, which will return true/false based on the in-memory index which is way faster.
For this usecase, you may not be able to segregate them into the 'sets' of aerospike. You need 100,000 sets. But as of now, Aerospike only supports 1024 sets.
Let me add a third option to your list. You can model the key itself to create virtual sets for you as below:
if you actual key is key1 and you want it to go to set1, you can set your mashed keys as set1_key1.
when you want to search for existence of key7 in set5, search for existence of set5_key7
If you go with this model, you are exploiting Aerospike's data-distribution, and load balancing to its best. The exists check will be the fastest as there will be no I/O.
Redis allows storing data in 16 different 'databases' (0 to 15). Is there a way to get utilized memory & disk space per database. INFO command only lists number of keys per database.
No, you can not control each database individually. These "databases" are just for logical partitioning of your data.
What you can do (depends on your specific requirements and setup) is spin multiple redis instances, each one does a different task and each one has its own redis.conf file with a memory cap. Disk space can't be capped though, at least not in Redis level.
Side note: Bear in mind that the 16 database number is not hardcoded - you can set it in redis.conf.
I did it by calling dump on all the keys in a Redis DB and measuring the total number of bytes used. This will slow down your server and take a while. It seems the size dump returns is about 4 times smaller than the actual memory use. These number will give you an idea of which db is using the most space.
Here's my code:
https://gist.github.com/mathieulongtin/fa2efceb7b546cbb6626ee899e2cfa0b
I am running a redis instance and want to limit the number of keys in an DB of the instance.
I checke the documentation and I saw that we can limit the memory of a complete instance .Any way to do that on DB level?
Thanks in Advance.
No, Redis does not have a function that can limit the amount of keys in the database.
The closest thing I can think of is checking the key number in your script, and the preventing the query of there is too many keys in the databse