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docs/de/distributed.md

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+# Distributed Systems
+
+BaraDB unterstützt verteiltes Deployment mit Raft Consensus, Sharding und Replikation.
+
+## Raft Consensus
+
+Leader Election und Log-Replikation:
+
+```nim
+import barabadb/core/raft
+
+var cluster = newRaftCluster()
+cluster.addNode("node1")
+cluster.addNode("node2")
+cluster.addNode("node3")
+
+let n1 = cluster.nodes["n1"]
+n1.becomeCandidate()
+n1.becomeLeader()
+let entry = n1.appendLog("SET key1 value1")
+```
+
+## Sharding
+
+Daten über Knoten verteilen:
+
+```nim
+import barabadb/core/sharding
+
+var router = newShardRouter(ShardConfig(
+  numShards: 4,
+  replicas: 2,
+  strategy: ssHash
+))
+router.rebalance(@["node1", "node2", "node3"])
+let shard = router.getShard("user_123")
+```
+
+### Sharding-Strategien
+
+| Strategie | Beschreibung |
+|----------|-------------|
+| `ssHash` | Hash-basiertes Sharding |
+| `ssRange` | Range-basiertes Sharding |
+| `ssConsistent` | Consistent Hashing |
+
+## Replikation
+
+```nim
+import barabadb/core/replication
+
+var rm = newReplicationManager(rmSync)
+rm.addReplica(newReplica("r1", "10.0.0.1", 9472))
+rm.connectReplica("r1")
+let lsn = rm.writeLsn(@[1'u8, 2, 3])
+rm.ackLsn("r1", lsn)
+```
+
+### Replikationsmodi
+
+| Modus | Beschreibung |
+|-------|--------------|
+| `rmSync` | Synchronous Replikation |
+| `rmAsync` | Asynchrone Replikation |
+| `rmSemiSync` | Semi-synchrone Replikation |
+
+## Gossip Protocol
+
+Membership und Failure-Erkennung:
+
+```nim
+import barabadb/core/gossip
+
+var g = newGossipManager()
+g.addNode("node1")
+g.addNode("node2")
+g.tick()  # Membership-Info austauschen
+```
+
+## Distributed Transactions
+
+Two-Phase Commit über Knoten:
+
+```nim
+import barabadb/core/disttxn
+
+var dt = newDistributedTxn()
+dt.prepare(@["node1", "node2"])
+dt.commit()
+```
+
+## Formale Verifikation
+
+Kern-Algorithmen für Distributed Systems sind formal in TLA+ spezifiziert und model-gecheckt:
+
+- **Raft Consensus** — `formal-verification/raft.tla`
+  - Verifiziert: ElectionSafety, StateMachineSafety
+- **Two-Phase Commit** — `formal-verification/twopc.tla`
+  - Verifiziert: Atomicity, NoOrphanBlocks
+- **Replication** — `formal-verification/replication.tla`
+  - Verifiziert: MonotonicLsn, AcksRemovePending
+
+TLC lokal ausführen:
+
+```bash
+cd formal-verification
+java -cp tla2tools.jar tlc2.TLC -config models/raft.cfg raft.tla
+java -cp tla2tools.jar tlc2.TLC -config models/twopc.cfg twopc.tla
+java -cp tla2tools.jar tlc2.TLC -config models/replication.cfg replication.tla
+```