I am working on a strategy game where you can conquer territory. Here is a screenshot of what it looks like (I own the purple land at the middle): enter image description here A map stores a plot object per coordinates (a coordinate is stored as a bytes32):

    mapping(bytes32 => Plot) public map;

When I draw the map in browser I need to check a big quantity of coordinates and this takes a lot of time. In fact, even if I try to do it in the contract and write a solidity function which iterates over the coordinates for me, this is still pretty slow. A solution I came up with is to create another map which stores informations about a 8*8 square space. A chunk is just a boolean. false = empty, true = at least one chunk. This theoretically allows me to be much faster on empty zones, but this is still pretty slow. What should I do?

  • What information are you storing in the map? The EVM is pretty bad at storing large amount of data. I'd store that type of data off-chain perhaps using something like zk snark for synchronization.
    – Ismael
    Jan 2, 2022 at 16:27
  • I am storing a Plot as value (a really simple struct) and a coordinates (serialized as a bytes32) as a key. This represents territories owned by players on a world map.
    – Th0rgal
    Jan 2, 2022 at 16:39

1 Answer 1


I guess you should emit an event once a plot is filled just like emit PlotClaimed(bytes32 coordinates) and then query those events on your script or even do a subgraph.

  • How using events would make my queries faster? I will look into TheGraph. Do you know if it is compatible with any evm chains (eg Cronos)?
    – Th0rgal
    Jan 2, 2022 at 16:13
  • Events are what index calls off chain so it's the only way for you to retrieve information without looping and I think The Graph doesn't support Cronos by now, but you could take a look at their website.
    – Omar
    Jan 2, 2022 at 21:31

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