In this article, I’ll try to explain the significance of Storage in Hyperledger Fabric and also the application that I have built to demonstrate the offchain storage implementation using the Go Programming language for Hyperledger Fabric. OffChain offchaindata OnChain and OffChain Transaction The transaction flow in any blockchain platform is performed in two different layers. The transactions committed to the distributed ledger in the blockchain network is considered to be transaction and the transactions that are executed outside of blockchain and stored into any collection database such as , are considered to be . OnChain CouchDB StateDB OffChain Blockchain more than just a Storage solution The concept of blockchain technology is to store a large set of data with the capability of providing the current state for each transaction. The blockchain network will maintain a transaction history log for any changes performed in the data. This kind of technique separates Blockchain from traditional database storage technologies that are only designed to store the data in an organized manner. distributed ledger Problem with OnChain transaction In general transaction takes a longer time to execute. The performance started to lag and takes much longer for the large queue of transactions that are waiting to be executed in the network. There is an extensive cost involved in terms of both business and storage space during transactions in Blockchain. OnChain OnChain OnChain Storage Calculation has performed an analysis to determine the extensive costs involved in terms of . IBM Storage space Source: https://www.ibm.com/downloads/cas/RXOVXAPM Facts Bitcoin stores 1400 transactions per block. Hyperledger blocks are 1 megabyte in size and have 1000 transactions per block. Each blockchain transaction is of 5 KB of the size that creates 205 TPS (transaction per second) Calculation of storage per TPS The transaction calculation is performed by comparing a company average working and . 8 hours per day 240 days per year (1 TPS/1000 TB)*1024 KB*3500 sec/hr*8 hr/day*240 days/year = 7,077,888 KB of data per transaction per year = 6,912 MB = 6.75 GB = .00659 TB/transaction/yr OnChain Financial costs for Blockchain also provided the average enterprise-level costs for and Non-Permissioned blockchain such as IBM Hyperledger Ethereum. IBM Hyperledger costs $1000 per month plus an additional $1000 per active node, so in total cost $6000 per month. The cost per transaction is Bitcoin is $1.30 and for Ethereum $0.25 per transaction. In Non-Permissioned blockchain, the per-transaction cost will change based on the current value of cryptocurrency . The cost for permission-based blockchain such as Hyperledger will vary by increasing of the number of nodes. So, in comparison with transaction costs, All the non-transaction data such as Pictures , Videos , PDF and other documents should not be stored in the Blockchain ledger. Solution with OffChain transaction The transaction does not store a transaction for every node in the storage space. The peer who is willing to store specific transactions can use offchain storage. OffChain increases computational efficiency that the computation is executed in offchain is not . OffChain deterministic consensus Design Implementation for OffChain Storage There are many offchain databases available to integrate with to store transaction details. The application that I have built is using as offchain storage. There will be a running that listens to the peers as client connection. So, the event listener process each block’s value into the OffChain storage(CouchDB). The technique is used to query offchain data from the CouchDB storage. Hyperledger Fabric offchaindata CouchDB GRPC event listener GRPC KVWriteSet MapReduce Github: https://github.com/Deeptiman/offchaindata What is MapReduce? is a programming model that is designed to process a large set of data parallelly on a large cluster. MapReduce MapReduce has two function — It provides the key-value pair list for a certain collection of documents. — It has a smaller set of key-value pairs that process multiple nodes in a collection. 1. Map Reduce 2. CouchDB uses the MapReduce technique to filter all collection documents. In the following example, we will see how MapReduce works for a User model. CouchDB uses the MapReduce technique to filter all collection documents. In the following example, we will see how MapReduce works for a User model. User Model SampleUser { Email Name Age Country } type struct string `json:"email"` string `json:"name"` string `json:"age"` string `json:"country"` Collection Documents in CouchDB So, we will create a MapReduce function to query Emails from the collection. Configure MapReduce for Email curl -X PUT http://127.0.0.1:5990/offchaindb/_design/emailviewdesign/ -d '{"views":{"emailview":{"map":"function(doc) { emit(doc.email,1);}", "reduce":"function (keys, values, combine) {return sum(values)}"}}}' -H 'Content-Type:application/json' Output { : , : , : } "ok" true "id" "_design/emailviewdesign" "rev" "1-f34147f686003ff5c7da5a5e7e2759b8" Parameters used Design View: emailviewdesign MapReduce Views : { : { : { : , : } } } "views" "emailview" "map" "function(doc) { emit(doc.email,1);}" "reduce" "function (keys, values, combine) {return sum(values)}" Query Reduce function to count total email curl -X GET http://127.0.0.1:5990/offchaindb/_design/emailviewdesign/_view/emailview?reduce=true Output { :[ { : , : } ]} "rows" "key" null "value" 7 Query Map function to list all emails curl -X GET http://127.0.0.1:5990/offchaindb/_design/emailviewdesign/_view/emailview?group=true Output { :[ { : , : }, { : , : }, { : , : }, { : , : }, { : , : }, { : , : }, { : , : } ]} "rows" "key" "alice@gmail.com" "value" 1 "key" "john@gmail.com" "value" 1 "key" "michale@gmail.com" "value" 1 "key" "mark@mail.com" "value" 1 "key" "bob@gmail.com" "value" 1 "key" "oscar@gmail.com" "value" 1 "key" "william@example.com" "value" 1 So, in this way MapReduce works. We can also create a MapReduce function for other nodes to query from the CouchDB . Conclusion All the queries performed in the offchain storage space and completely ignoring the onchain ledger. This increases computational efficiency in terms of querying a large set of data. There is no transaction cost involved in performing an offchain query as a similar onchain query has higher transaction costs. In the case of , OffChain storage can also be used to store sensitive private data as not all the participants in the blockchain network are aware of the additional separate layer of storage is used to store the data. Public Blockchain So, this is the overview of understanding the significant of offchain storage in any blockchain network. Please check the application at and share your feedback use-case offchaindata Github I hope you find this article useful :) Thanks
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