Could nix-index make store optimization faster?

[mikepurvis]

Running nix store optimize can be slow on even relatively small stores, since it needs to hash everything to find files that are identical between store paths. Could there be a role for nix-index in supplying individual file hashes for known store paths, so that optimization becomes trivial?

[SuperSandro2000]

Could there be a role for nix-index in supplying individual file hashes for known store paths, so that optimization becomes trivial?

The cache of nix-index is not always up to date and identically to the nix store but since binaries rarely move around that is not a problem. Using such stale cache for optimization is probably not beneficial.