Constant DATABASE_FORMAT_MINOR_VERSION 

const DATABASE_FORMAT_MINOR_VERSION: u64 = 0;

The database format minor version, incremented each time the on-disk database format has a significant data format change.

Significant changes include:

• adding new column families,
• changing the format of a column family in a compatible way, or
• breaking changes with compatibility code in all supported Zebra versions.

Version history:

• 29.0.0: the NU7 Network Sustainability Mechanism pool widens new ValueBalance writes from 48 to 56 bytes and BlockInfo writes from 52 to 60 bytes. Legacy records remain readable with a zero NSM balance. The registered upgrade reuses compatible v28 state by moving its network directory to state/v29, without a resync or record migration. Retain a v28 backup for rollback: disabling old-database cleanup does not prevent this move, and v28 readers cannot use new records.
• 28.0.0: the NU6.3 Ironwood shielded pool. Adds the ironwood_* column families (initially empty) and widens the chain value pool ValueBalance serialization from 40 to 48 bytes for the ironwood pool (read code accepts 32/40/48-byte records). Also widens the history-tree zcash_history::Entry records from 253 to 326 bytes, because NU6.3 adds Ironwood fields to zcash_history::NodeData (read code accepts the legacy 253-byte width and zero-pads it up to the current width). New CFs are created and the wider records are read in place when the database is opened, so this is a major bump that is restorable from the previous major database format version (no resync, no data migration).