Many people are using this as a "let's see what this does" command
when something doesn't work as they thought it should, and thus
destroying info that they might still need.
When creating/restoring wallet, if --restore-height option is not used the current estimate
height is used for starting the scan. In other words it is assume we are creating a new account.
If a pre-fork output is spent on both Monero and attack chain,
any post-fork output can be deduced to be a fake output, thereby
decreasing the effective ring size.
The segregate-per-fork-outputs option, on by default, allows
selecting only pre-fork outputs in this case, so that the same
ring can be used when spending it on the other side, which does
not decrease the effective ring size.
This is intended to be SET when intending to spend Monero on the
attack fork, and to be UNSET if not intending to spend Monero
on the attack fork (since it leaks the fact that the output being
spent is pre-fork).
If the user is not certain yet whether they will spend pre-fork
outputs on a key reusing fork, the key-reuse-mitigation2 option
should be SET instead.
If you use this option and intend to spend Monero on both forks,
then spend real Monero first.
This maps key images to rings, so that different forks can reuse
the rings by key image. This avoids revealing the real inputs like
would happen if two forks spent the same outputs with different
rings. This database is meant to be shared with all Monero forks
which don't bother making a new chain, putting users' privacy at
risk in the process. It is placed in a shared data directory by
default ($HOME/.shared-ringdb on UNIX like systems). You may
use --shared-ringdb-dir to override this location, and should
then do so for all Monero forks for them to share the database.