Irreversible Migration
An irreversible migration is a structural change to data or systems that cannot be rolled back without extreme difficulty or permanent data loss.
Triggers: 1. Lossy compression. 2. Schema normalization/denormalization. 3. Physical hardware destruction. 4. One-way hashing.
graph LR
Center["Irreversible Migration"]:::main
Rel_rpc_node["rpc-node"]:::related -.-> Center
click Rel_rpc_node "/terms/rpc-node"
Rel_sandboxing["sandboxing"]:::related -.-> Center
click Rel_sandboxing "/terms/sandboxing"
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classDef child fill:#0f172a,stroke:#10b981,color:#94a3b8,rx:5,ry:5;
classDef related fill:#0f172a,stroke:#8b5cf6,stroke-dasharray: 5 5,color:#94a3b8,rx:5,ry:5;
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🧒 Explain Like I'm 5
Imagine moving from a house to a tiny apartment and throwing away all the furniture that doesn't fit. Once the trash truck takes it away, you can't move back into the big house with your old furniture anymore. You've made an irreversible migration.
🤓 Expert Deep Dive
Technically, irreversible migrations occur when the 'State Transition' is non-isomorphic. For example, moving from a 'Relational' database to a 'Key-Value' store often involves 'Flattening' data, which destroys the relational schema metadata. In blockchain, a 'Hard Fork' that changes the transaction format is irreversible for nodes that adopt the new rules; they can no longer validate the old chain without a separate 'Replay' mechanism. The primary mitigation strategy for irreversible migrations is 'Shadow Migration', where the new system runs in parallel with the old one for a verification period before the 'Terminal Switchover' occurs. Another approach is 'Expansion-Contract' (Parallel-run), where you add the new fields first, migrate data, and only delete the old fields months later.