Why don't we have more checkpoints?

[abhiShandy]

Is your feature request related to a problem? Please describe.

src/chainparams.cpp:146 has few checkpoints for the mainnet using a table of block and blockhash. Why does it end at block 295000?

Describe the solution you'd like

Either add a comment with an explanation for given number checkpoints or add checkpoints at an agreed block interval.

Describe alternatives you've considered

Additional context

[brunoerg]

See this answer on bitcoin stackexchange.

I think they are not so useful and if we need to use them, it means the system is already broken.

[kristapsk]

It is not uncommon for people to add additional checkpoints to their nodes. For example, Bitcoin Knots, which is patched version of Bitcoin Core by @luke-jr, adds additional checkpoints.

[maflcko]

Could make sense to mention briefly in the code what https://bitcoin.stackexchange.com/a/70824/3576 says?

[brunoerg]

I think so, @MarcoFalke.

[abhiShandy]

@brunoerg Shall I remove the checkpoints (and the validation code) to avoid the confusion?

[sipa]

@abhiShandy No, they're still needed to prevent low-difficulty header spam. It's not a particularly strong attack, but without checkpoints it's trivial. The current checkpoints suffice to make it sufficiently expensive.

[adamjonas]

Closing since the questions seems to be answered sufficiently.

Checkpoints are currently required, but see #25725 for a glimpse into the future.