Banking ledger during partition

Split-brain writes

## CAP under partitions

Consistency and availability tensions appear only when messages between nodes are lost or delayed.

Correctness under failure

CAP Theorem & Consistency Models

During a network partition when nodes cannot communicate.

Ignore failure modes and deploy globally without measurement.

Claiming “CA” in a distributed system

Prefer synchronous coupling everywhere to simplify tracing.

CAP Theorem & Consistency Models: core idea 1

Single-node databases with no partition risk

Consistency models define client-visible ordering

CAP Theorem & Consistency Models: when to apply (1)

CAP Theorem & Consistency Models: when to avoid (1)

CAP Theorem & Consistency Models: trade-off — Strong consistency

Higher latency and availability hits during partitions

Treat every workload as identical and reuse one global configuration.

CAP Theorem & Consistency Models: cost of Strong consistency

Ignore failure modes because retries always succeed eventually.

Split-brain writes: Two leaders accept conflicting writes.

CAP Theorem & Consistency Models: failure — Split-brain writes

Skip observability and scale first; tune correctness only after an outage.

Fencing tokens, epoch numbers, or quorum leases.

Ignoring client read-your-writes expectations

CAP Theorem & Consistency Models: mitigate Split-brain writes

CAP Theorem & Consistency Models: mistake to avoid (1)

Optimize for lowest memory at the cost of undefined consistency guarantees.

CP design may reject writes; AP design may expose divergent balances until merge.

CAP Theorem & Consistency Models: example outcome (1)

Name the partition behavior first, then pick a consistency model and client contract that matches product risk—not the buzzword on the slide.

CAP Theorem & Consistency Models: spark takeaway

During a network partition, a distributed store cannot simultaneously provide both strong consistency and full availability; engineering chooses which guarantee to weaken and how clients observe stale reads.

CAP Theorem & Consistency Models

💡 Why It Matters

🌐 Real-World Production Usages & Examples

Banking ledger during partition

✓ When to Use

✕ When NOT to Use

🔑 Core Architecture & Rules

⚖️ Architectural Trade-Off Analysis

Strong consistency

⚠️ Failure Modes & Mitigations

Split-brain writes

🛠️ Example Usages

Explore Related Concepts & Guides

Quorum & Replication

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