Note
If you are new to the blockchain technology, taking our Introduction to Blockchain Technology self-paced course is highly recommended. Also, for a comprehensive coverage of blockchain development in Ethereum or mastering Solidity programming, taking our below self paced courses is highly recommended:
Recap
In our previous article (Review of challenges in distributed systems), we covered the challenges of using distributed database systems.
In this article, we discuss three properties of the CAP theorem and how they are used in different distributed database systems.
The CAP theorem
Proposed by Eric Brewer, a Berkeley computer scientist, the CAP theorem asserts that any distributed system with shared state can only have at most, two desirable properties out of the following three:
- Consistency
- Availability
- Partition tolerance
There is no guarantee that network nodes are free of failure in a distributed heterogeneous environment. Therefore, the CAP theorem suggests that the designer of large distributed systems has to make a trade-off between consistency and availability. Traditional RDBMS is more targeted to ensure consistency and availability in a centralized system.
The following diagram illustrates the three properties of the CAP theorem and the designer’s choices in different distributed database systems:
For example, the Cassandra database, a massively scalable open source NoSQL database from the Apache foundation, is the right choice for use cases where scalability, high availability, and performance are the most important design objectives.
Design choices made in Cassandra favor availability and partition tolerance over consistency, although you can eventually make it consistent by tuning the Cassandra database with the replication factor and consistency level. Its linear scalability, together with its strong fault-tolerance on commodity hardware or cloud infrastructure, makes it a perfect option for many mission critical applications. CouchDB falls in the same category.
On the other hand, MongoDB is strongly consistent by default, which also means it compromises availability. It employs a single-master system to ensure all writes occur on the primary node, and nothing is written to the secondary node. All reads go to the primary node by default. If the primary goes down, no writes can happen until a secondary takes over as the primary. HBase falls in the same category.
Next Article
In our next article (Horizontal Scaling versus Vertical Scaling in Distributed Systems), we discuss the differences between horizontal and vertical scaling in distributed systems.
This article is written in collaboration with Brian Wu who is a leading author of “Learn Ethereum: Build your own decentralized applications with Ethereum and smart contracts” book. He has written 7 books on blockchain development.
Resources
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- Hyperledger Fabric for system admin versus developers
- How to harness blockchain for environmental and corporate sustainability
- Review of Initial Coin Offering, Security Token Offering and asset tokenization use cases and best practices
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- Hyperledger Fabric for entrepreneurship- 21 blockchain business use cases
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Self-Paced Blockchain Courses
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- Intro to Blockchain Technology
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- Intro to Blockchain Cybersecurity
- Learn Solidity Programming by Examples
- Introduction to Ethereum Blockchain Development
- Learn Blockchain Dev with Corda R3
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Live Blockchain Courses
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Articles and Tutorials on Blockchain Technology
If you like to learn more about blockchain technology and how it works, reading the following articles is highly recommended:
- History and Evolution of Blockchain Technology from Bitcoin
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- Blockchain Crowdfunding Security Token or Initial Coin Offerings
- A beginner Guide to Blockchain Technology
- How Decentralized Peer-To-Peer Network Works
- How blocks are added to the blockchain
- How Public and Private Keys of Cryptography Work
- What Is A Cryptographic Hash Function
- How Digital Signature Works In Blockchain
- The role and types of consensus mechanism in blockchain
- How Proof-of-Work Consensus Works in Blockchain
- How Proof of Stake Consensus works in Blockchain
Articles and Tutorials on Ethereum and Solidity
If you like to learn more about blockchain development in Ethereum with Solidity, reading the following articles and tutorials is highly recommended:
- Review of Architecture and Components of Ethereum
- Comprehensive Blockchain Ethereum Developer Guide from Beginner to Advance Level
- How to Write Ethereum Smart Contracts with Solidity in 1 hour
- Review of Architecture and Components of Ethereum
- How Ethereum Manages Accounts
- How Ethereum Manages Transactions
- How Smart Contracts Work in Ethereum
- How Ether and Gas Work in Ethereum
- How Ethereum Virtual Machine works
- How address and wallet work in Ethereum
- How mining works in Ethereum
- List of Tools and Technologies in Ethereum Ecosystem
- Review of challenges in distributed systems
- Review of Cap Theorem in Distributed Systems
- Horizontal Scaling versus Vertical Scaling in Distributed Systems
- How to Scale up Ethereum Blockchain Applications
- Review of scaling solutions for Ethereum
- How to Manage Ethereum State Channel with Raiden
- How Plasma Chains Work in Ethereum
- How Sharding and Gasper work in Ethereum
- How Proof-of-Stack Consensus Works in Ethereum
- A roadmap for Implementing Ethereum 2.0
- How to work with Decentralized Data and Content Storage in Ethereum
- How Decentralized Messaging with Whisper Works in Ethereum
- Review of Infura for Ethereum Development
- Review of Infura Ethereum API
- How to Use Remix with Infura for Ethereum Development
- How Ethereum Client API Works
- How Ethereum IPFS Storage Works
- How to Install and Start Ethereum IPFS Storage
- How to Run Ethereum IPFS Storage
- How to Work with Ethereum Swarm Storage
- How to Install Ethereum Swarm Storage
- How to Handle Ethereum Messages with Whisper
- Review of Popular Ethereum Smart Contract Libraries
- Review of Private and Permissioned blockchain
- How to Set up a Local Private Ethereum Blockchain
- How to Run Geth on a Local Private Ethereum Blockchain
- How to Build a Local Private Ethereum Blockchain with Mining
- How to Run Geth on a Local Private Ethereum Blockchain with Mining
- How to Create an Account on a Local Private Ethereum Blockchain
- How to Use Ethereum Optional Flags with New Chains
- Review of Ethereum Options for Development and Testing
- Review of Ethereum Developer Chain Options
- Review of Ethereum API and Console Options
- Review of Ethereum Networking Options
- Review of Ethereum Transaction Pool Options
Articles and Tutorials on Hyperledger Family
If you like to learn more about blockchain development with Hyperledger, reading the following articles and tutorials is highly recommended:
- Introduction to Hyperledger Architecture, Projects, Tools and Libraries
- Complete Review of Hyperledger Fabric Architecture and Components
- Hyperledger Fabric for System Administers versus Developers
- How to use Prometheus and Grafana to monitor Hyperledger Fabric
- Blockchain Developer Guide- How to Install Hyperledger Fabric on AWS
- Blockchain Developer Guide- How to Install and work with Hyperledger Sawtooth
- Blockchain Developer Guide- How to Install Hyperledger Burrow on AWS
- Blockchain Developer Guide- How to Install Hyperledger Iroha on AWS
- Blockchain Developer Guide- How to Install Hyperledger Indy and Indy CLI on AWS
- Blockchain Developer Guide- How to Install Hyperledger Seth and Docker on AWS
- Blockchain Developer Guide- How to Configure Hyperledger Sawtooth Validator and REST API on AWS
- Blockchain Developer Guide- How to Build Transaction Processor as a Service and Python Egg for Hyperledger Sawtooth
- Blockchain Developer Guide- How to Deploy Ethereum Smart Contracts with Hyperledger Burrow
- Blockchain Developer Guide- How to Create Cryptocurrency Using Hyperledger Iroha CLI
- Blockchain Developer Guide- How to Explore Hyperledger Indy Command Line Interface
- Blockchain Developer Guide- Comprehensive Blockchain Hyperledger Developer Guide from Beginner to Advance Level
- Introduction to Hyperledger Sawtooth Blockchain Development
Articles and Tutorials on R3 Corda
If you like to learn more about blockchain development on Corda , reading the following articles and tutorials is highly recommended:
Articles and Tutorials on Other Blockchain Platforms
If you like to learn more about blockchain development in other platforms, reading the following articles and tutorials is highly recommended: