SST file format incompatibility during RocksDB version downgrade

Forward Compatibility Constraints

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RocksDB ensures that newer versions can read SST files created by older versions. However, forward compatibility is not guaranteed. When a database is upgraded to a newer version, the engine may rewrite SST files during compaction or ingestion using a more recent on-disk format version embedded in the file footer.

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If a system must be reverted to a previous version after an upgrade has already triggered these rewrites, the older binary will encounter files it cannot parse, leading to a failure to open the database.

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Given that recovery typically relies on restoring a snapshot or backup from before the upgrade, there is uncertainty regarding the stability of the SST format across minor version increments.

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• Does a minor version update always maintain the same SST file format version?
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• At what specific threshold of version increments does the on-disk format become incompatible with previous releases?
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