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I'm working on a smart contract in which we need to store some addresses along with their pending rewards periodically,

so the most first approach is to have a mapping of addresses to an int, like below:

mapping(address => uint256) pendingRewards;

The problem is that when you want to set/update all these data at once, it will cost a lot of gas to loop through the mapping and update them all.

so in other words, let's say I have a table of addresses and pending rewards, consider it's a huge huge table, what would be the best practice to set/update these data into a smart contract?

!! MerkleTree would not solve the problem because we can't retrieve pendingReward with the address as the key from that.

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  • By the way, the Merkle Trees is the most common solution, you store the huge mapping offchain - Db, Excel, Json, etc, and users will claim rewards by providing their reward amount from offchain storage.
    – tenbits
    Nov 29, 2023 at 19:51
  • thank you @tenbits this is actually what I was thinking about. also we can keep the totalClaimed in the contract, which will solve my issue. so merkleTree + offchain data is the solution!
    – S Arv
    Nov 30, 2023 at 12:28

1 Answer 1

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The problem is that when you want to set/update all these data at once, it will cost a lot of gas to loop through the mapping and update them all.

You need to design your smart contract logic in a way that there is no need to do this kind of batch update operations.

This is quite well understood problem. There are multiple well-known decentralised projects like Uniswap, Sushi, Balancer which you can study to understand how it is done.

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  • could you please provide more detail on where exactly should I look for?
    – S Arv
    Nov 29, 2023 at 19:49
  • Start with Sushiswap v2 source code and their reward pools. Nov 30, 2023 at 4:16
  • i'm not looking for a reward pool or staking logic, you didn't get my question. but thank you anyways.
    – S Arv
    Nov 30, 2023 at 12:26

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