Older LND versions could create multiple payments for the same hash.
We need to preserve those historical records during KV→SQL migration,
but they don’t fit the normal payment schema because we enforce a
unique payment hash constraint. Introduce a lean payment_duplicates
table to store only the essential fields (identifier, amount,
timestamps, settle/fail data).
This keeps the primary payment records stable and makes the migration
deterministic even when duplicate records lack attempt info. The table
is intentionally minimal and can be dropped after migration if no
duplicate payments exist.
For now there is no logic in place which allows the noderunner to
fetch duplicate payments after the migration.
Previously a one(intent)-to-many(payment) relationship it is now
changed to a one-to-one relationship because a payment request
only can have 1 payment related to it. Looking into the future
with BOLT12 offers, the fetched invoice from the offer could be
stored here as well and the relationship would still hold.
ziggie