I see sharding and swarms are in the IOTA roadmap. The question is why is sharding necessary? Can it be compared to the way Ethereum plans to shard?

The only info I managed to find was a paragraph on the IOTA blog which is vague.

  • I don’t know if I correctly understood the meaning of sharding and swarms. Where can I read about them in IOTA roadmap?
    – blockmined
    Commented Jan 24, 2018 at 13:44
  • Here: blog.iota.org/iota-development-roadmap-74741f37ed01 Commented Jan 24, 2018 at 14:14
  • IoT does not have a lot of processing and storage, It just make sense to keep the portion of the tangle (shard) that is related and of interest for the IoT device(s).
    – AlbertK
    Commented Jan 26, 2018 at 7:20
  • I understand the general concepts of sharding, I'm more interested on how is this to be achieved. Commented Jan 26, 2018 at 8:34

1 Answer 1


Sharding is the process of dividing up data. For example, if you had a database containing information about all of the people alive today it could be quite large (depending on what information you store about each person).

Sharding lets you divide the dataset up across machines based on some criteria. For example, you could set up X shards and choose which shard a record goes to based on the year the person was born.

When you want to list everyone named "Smith" then each of the shards is contacted and told to return a list of IDs of people named "Smith" - the client (your computer) then puts the results from all shards together to give you a complete picture (all Smiths from all shards) - but showing only the data you asked for (say ID, GivenName, FamilyName, Title) so that it fits into memory.

  • Does it in any way relate to processing power? And most importantly, does it anything to do between splitting transaction processing as described in iota.stackexchange.com/questions/1320/… Commented Feb 5, 2018 at 10:33
  • 1
    It's to do with storage restrictions and/or parallelization. For example, if you want an average transaction amount you would scan your own data and for each record add to an accumulator in the format TotalValue (number), TransactionCount (number) - You can then ask other shards to do the same. Importantly you can then add TotalValue from each response and also TransactionCount from each, and then perform the same averaging algorithm as if they were simply local records. Google MapReduce Commented Feb 5, 2018 at 14:00
  • I'm aware of MapReduce and it's benefits and sharding is clear the way you describe it, however I would like to know how it's related to actual transaction processing in the network. Taking Ethereum as an example - every node has to process every transaction, hence it's so slow and needs to shard so that every miner does not need to process every transaction. Judging by the link provided above every full node has to validate every transaction eventually. I was wondering if sharding is related to that fact Commented Feb 6, 2018 at 14:31
  • It looks like a full node will validate everything, and sharded nodes will validate their subset - but will query other shards/full-nodes to ensure there is no double-spend etc (i.e. part of the validation). Commented Feb 6, 2018 at 16:01
  • That seems logical to me as well, however do you have any reference to back up your claims? Commented Feb 7, 2018 at 10:11

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