feat: add index for stacks block id in nakamoto_block_headers

[kantai]

Description

Optimization: add index for index_block_hash in nakamoto_block_headers

[jcnelson]

Do we need a new schema version?

[kantai]

Do we need a new schema version?

I didn't think so -- doesn't the index creation code just always run and check if indexes need to be created?

[jcnelson]

Ah, yes, you're right -- specifically for the chainstate (we really should do something about that too -- I bet those transactions are really unecessary)

oops, I missed the Self::need_schema_migrations() call

[kantai]

Ah, yes, you're right -- specifically for the chainstate (we really should do something about that too -- I bet those transactions are really unecessary)

Nope, I was wrong!

        if create_flag {
            // instantiate!
            StacksChainState::instantiate_db(mainnet, chain_id, index_path, true)
        } else {
            let mut marf = StacksChainState::open_index(index_path)?;
            if !Self::need_schema_migrations(marf.sqlite_conn(), mainnet, chain_id)? {
                return Ok(marf);
            }

            // need a migration
            let tx = marf.storage_tx()?;
            StacksChainState::apply_schema_migrations(&tx, mainnet, chain_id)?;
            StacksChainState::add_indexes(&tx)?;
            tx.commit()?;

Will add a schema version.

[CharlieC3]

Minor nit, but fine to ignore

[obycode]

LGTM, just the comment nit.

[CharlieC3]

LGTM!