Is possible to start from 0 for a light client?

[aurexav]

I want all the headers.

[ligi]

Out of curiosity: What is your use case?
Are you aware that the light client can still retrieve the old headers?

[zsfelfoldi]

There is currently no option to disable using the CHT if there is one present. It wouldn't be hard to add it but I don't see why it's necessary since as @ligi wrote the old headers can still be safely retrieved on demand.
Edit: one valid reason might be if you don't want to trust the CHTs and want to verify the entire chain yourself. See #21337 (comment)

[aurexav]

Out of curiosity: What is your use case?
Are you aware that the light client can still retrieve the old headers?

I want to calculate the the MMR root for every header.

All I need is the headers data (other data is useless to me), so I don't want to waste too much disk space. Any way to achive this?

BTW, the infura or other public API is slow and limited on request. So I decide to run a node myself.

There is currently no option to disable using the CHT if there is one present. It wouldn't be hard to add it but I don't see why it's necessary since as @ligi wrote the old headers can still be safely retrieved on demand.

But too slow. Request the old header from outside everytime I need it.

[rjl493456442]

I think it's a valid feature request if you want to recalculate some other things with all headers from the genesis. Any option? @zsfelfoldi

[rjl493456442]

The feature is implemented in #22123