Matching: is this event schema change backward, forward, full or breaking? Intermediate

Four services consume OrderPlaced and deploy on their own schedules, so every schema change meets readers and writers of different versions. Drag a verdict onto each change.

• Each explanation names the side that breaks: the new consumer reading old records or the old consumer reading new records.
• Avro verdicts follow the Avro spec’s Schema Resolution rules and were reproduced with avsc; the Protobuf case follows the proto3 guide.

Matching

Which compatibility does this schema change have?

The topic orders.order-placed carries OrderPlaced v1 (Avro unless noted). Four consumers (billing, inventory, email, analytics) deploy independently. Drag a verdict onto each change.

Tip: ask two questions. Can a new reader read old records? (backward) Can an old reader read new records? (forward) Both yes = full, both no = breaking.

Tap Choose answer on each case. On a computer you can drag a card below onto a case.

Forward compatibleBackward compatibleFully compatibleBreaking

Solved 0/8 · 0 mistakes

1Add a currency field with a default.

{ "name": "currency", "type": "string", "default": "VND" }

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2Add a currency field without a default.

{ "name": "currency", "type": "string" }

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3Remove the optional couponCode field, which v1 declared with a default.

// v1
{ "name": "couponCode", "type": ["null", "string"], "default": null }
// v2: field removed

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4Rename amount to totalAmount without an alias.

// v1
{ "name": "amount", "type": "long" }
// v2
{ "name": "totalAmount", "type": "long" }

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5Widen amount from int to long because large orders overflow.

// v1
{ "name": "amount", "type": "int" }
// v2
{ "name": "amount", "type": "long" }

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6Narrow amount from long to int to save space.

// v1
{ "name": "amount", "type": "long" }
// v2
{ "name": "amount", "type": "int" }

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7Protobuf: field string coupon_code = 7 was deleted last quarter. A new field reuses number 7.

message OrderPlaced {
  string order_id = 1;
  int64 discount = 7; // was: string coupon_code = 7
}

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8Add symbol REFUNDED to the status enum. The v1 enum has no default.

// v1
{ "type": "enum", "name": "Status", "symbols": ["PLACED", "PAID"] }
// v2
{ "type": "enum", "name": "Status", "symbols": ["PLACED", "PAID", "REFUNDED"] }

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For deploy order, Schema Registry modes and how to ship a breaking change, read event schema evolution.