Smart contract pagination for list

• A contract has an infinite internal storage
• There are 2 limits to practicality: gas costs and the block gas limit.

Example

Create 5k5 players, read one time

https://testnet.bscscan.com/address/0x721ff9e58831b698efd26b9ac744cf8f0aaecbc2#readContract

Max Gas Limit is 28,500,000 at May 12, 2021 = 0.22BNB ~ $145

• [WRITE] Can add 500 player in 1 tx
• [READ] Can not get all 5600 players (1600 is ok)

call to TestPlayerRead.getPlayers
call to TestPlayerRead.getPlayers errored: Error: Internal JSON-RPC error. { "code": -32000, "message": "out of gas" }

• [READ] To read all data, should use paging approach

TestPlayerRead.sol

// SPDX-License-Identifier: MIT
pragma solidity 0.8.3;

contract TestPlayerRead {

    struct Player {
        uint id;
    }

    Player[] public playerList;
    mapping(uint => Player) public playerMap;

    constructor () {}

    function addPlayers(uint more) public {
        uint currentSize = getPlayerSize();
        for (uint i = currentSize; i <…