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Blockchain Technology

Ethereum Constantinople Upgrade Explained

By December 12, 2018 December 14th, 2018 No Comments

The Ethereum Constantinople upgrade has now been set in stone. After a recent developer meeting, consensus was reached to implement the huge upgrade in January. Specifically, at block height 7,080,000, which based on the current block time is around the 14th Jan 2019.

The upgrade is implementing 5 core features, and will be done via a hard fork. The hard fork ensures the changes are not backwards compatible, and requires nodes to signal the new chain. Likewise, Ethereum miners will also need to switch to the newer forked chain.

So what does the Ethereum Constantinople Upgrade bring to the table in terms of blockchain technology, and what will it change? Let’s explore each feature one by one.

Bitwise Shifts

Proposed in EIP (Ethereum Improvement Proposal) 145, Bitwise Shifting is a change to how the Ethereum Virtual Machine adds numbers. The upgrade will greatly improve the efficiency for certain sections of code used by developers. This efficiency gain is up to 91%, which ends up being a large saving in GAS costs. Lower GAS means smart contracts are cheaper to operate, a win for developers and a win for end-users.

New opcode (EXTCODEHASH)

The aptly named EXTCODEHASH opcode comes from EIP1052. The upgrade seeks to further increase efficiencies for the EVM by introducing a new ‘opcode’.

Opcodes stand for ‘operation code’, and are the backend instruction of a programming language. Developers write in a language (which is Solidity in Ethereum’s case) and the opcode is the instruction given to the machine from that language.

EIP1052 introduces a new opcode that will perform an existing function, but with greater efficiency. Similarly to Bitwise Shifting, this will also lead to reduced GAS costs. Another win for devs and users. 

Net gas metering changes

Proposed in EIP1283, an existing opcode is getting changes to improve GAS efficiency.

The opcode getting the changes is called SSTORE, and is a function that stores data on the Ethereum blockchain. It’s the most expensive form of storage as the blockchains space is limited.

Efficiencies gained are yet again, a win for developers building DApps and writing smart-contracts, and ultimately the end-users.

Skinny Create2

You have to be amused by these EIP names don’t you. I love the non-standard naming conventions Ethereum has for its improvement proposals. It makes the whole thing just more interesting.

Anyway, Skinny Create2 comes under EIP1014 and was written and proposed by Vitalik Buterin himself. The upgrade brings a new and additional contract creation function.

To explain, the function is key for future on-chain and off-chain work as it allows a contract to interact with an address that does not exist yet, but will some time in the future. In other words, it will reduce unnecessary calculations on-chain.

Difficulty Bomb and Block Reward Adjustment

Last but not least, we have saved the best for last. EIP 1234 is arguably the most significant change coming in the Ethereum Constantinople Upgrade.

The difficulty bomb (also known as ‘the ice age’), is a mining difficulty adjustment. It was programmed into Ethereum to adjust close to the time it transitioned from Proof-of-work to Proof-of-stake. Unfortunately, this transition has been delayed, so the difficult bomb needs to be adjusted.

The block reward adjustment will reduce the amount of Ether awarded to miners from 3 ETH to 2 ETH. This essentially will reduce the supply of ETH into circulation by around 33% at the time of the upgrade. The intention of the reduction is to help with system stability as the difficulty bomb is delayed.


The Ethereum Constantinople upgrade is a big one. Ultimately what it brings is more efficiencies and capabilities for developers. Furthermore, the reduction in GAS costs will lead to more complex and exciting DApps for us users. Bring on more blockchain games I say.

Ethereum’s open source nature gives it the strength and resilience to continuously innovate and grow over time. I really can’t wait to see what is in store for Ethereum over the coming years following Constantinople.

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