What Is Sharding?

Sharding is a database partitioning technique used by blockchain companies with the purpose of scalability, enabling them to process more transactions per second. Sharding splits a blockchain company's entire network into smaller partitions, known as "shards." Each shard is comprised of its own data, making it distinctive and independent when compared to other shards.

Sharding can help reduce the latency or slowness of a network since it splits a blockchain network into separate shards. However, there are some security concerns surrounding sharding in which shards can be attacked.

Key Takeaways

  • Sharding is a database partitioning technique being considered by blockchain networks and being tested by Ethereum.
  • The more users that blockchain networks take on, the slower the network becomes, leading to significant latency.
  • Sharding can improve network latency by splitting a blockchain network into separate shards—each with its own data, separate from other shards.
  • Security concerns surrounding sharding include a hack or shard takeover, where one shard attacks another, resulting in a loss of information.

Understanding Sharding

Blockchain networks and their respective cryptocurrencies are gaining in popularity due to the widespread application of the technology, which includes supply chain management and financial transactions. As the popularity of blockchain grows, so too does the workload and transactional volume that is handled by the network. If we think of a blockchain as a shared database, as more and more data is added, the network needs to find new ways to be able to process all of that data efficiently and quickly, which is where sharding can help.

Distributed Ledger

The distributed ledger of blockchain technology makes it attractive since it allows the transactions to be consensually shared across multiple sites and geographies. As transactions are recorded, copies are sent to the shared network within seconds creating public "witnesses." If one portion of the network falls victim to fraud or a malicious attack, the shared network's participants can identify what was changed by the fraudsters since they all maintain a copy of the ledger's transactions. As a result, blockchain technology and its distributed ledger system can help reduce fraud and limit the damage from cyberattacks, such as a hack.


However, one of the major challenges with blockchain technology is that as additional computers are added to the network and more transactions are processed, the network can become bogged down, slowing the process—called latency. Latency is a hurdle to blockchain being adopted for widespread use, particularly when compared to the current electronic payment systems that work quickly and efficiently. In other words, scalability is a challenge for blockchain since the networks may not be able to handle the increased amounts of data and transaction flow as more and more industries adopt the technology.

One of the solutions being considered for creating latency-free scalability is the process of sharding. Sharding is designed to spread out the workload of a network into partitions, which may help reduce latency and allow more transactions to be processed by the blockchain.

Three traits that blockchain networks seek to employ are decentralization, scalability, and security. 

How Sharding Is Accomplished

Before exploring how sharding is accomplished within a blockchain network, it's important to review how data is currently stored and processed.

Blockchain Nodes

Currently, in blockchain, each node in a network must process or handle all of the transaction volumes within the network. Nodes in a blockchain are independent and are responsible for maintaining and storing all of the data within a decentralized network. In other words, each node must store critical information, such as account balances and transaction history. Blockchain networks were established so that every node must process all of the operations, data, and transactions on the network.

While it ensures a blockchain’s security by storing every transaction in all of the nodes, this model slows transaction processing considerably. Slow speeds for processing transactions do not bode well for a future in which blockchain becomes responsible for millions of transactions. 

Sharding can help since it partitions or spreads out the transactional workload from a blockchain network so that every node doesn't need to handle or process all of the blockchain's workload. In a way, sharding compartmentalizes the workload into partitions or shards.

Horizontal Partitioning

Sharding can be accomplished through the horizontal partitioning of databases through division into rows. Shards, as the rows are called, are conceptualized based on characteristics. For example, one shard might be responsible for storing the state and transaction history for a specific type of address. Also, it might be possible to divide shards based on the type of digital asset stored in them. Transactions involving that digital asset might be made possible through a combination of shards.

As an example, consider a rental real estate transaction in which multiple shards are involved. These shards correspond to different entities involved in the transaction, from customer name to digital keys configured into a smart lock that is made available to the renter upon rent payment.

Shard Sharing

Each shard is still able to be shared amongst the other shards, which maintains a key aspect to blockchain technology—the decentralized ledger. In other words, the ledger is still accessible to every user allowing them to view all of the ledger transactions.

Sharding and Security

One of the main issues in the practice that has arisen is security. Though each shard is separate and only processes its own data, there is a security concern regarding the corruption of the shards, where one shard takes over another shard, resulting in a loss of information or data.

If we think of each shard as its own blockchain network with its authenticated users and data, a hacker or through a cyber attack could take over a shard. The attacker could then introduce false transactions or a malicious program.

Ethereum, one of the most prominent blockchain companies, is on the front line of testing sharding as a possible solution to latency and scalability issues. Ethereum has combated the potential of a shard attack by randomly assigning nodes to certain shards and constantly reassigning them at random intervals. This random sampling would make it difficult for hackers to know when and where to corrupt a shard.

Also, it's important to note that sharding is still in the early testing phase of being used for blockchain networks. As a result, all of the potential issues and challenges have yet to be worked out.