[BUG] DynamoDB does not enforce the 2048/1024 byte key length limits

[rfoel]

Service

DynamoDB

AWS API Action

PutItem (and anything else that writes a key)

Expected behavior

DynamoDB caps key lengths:

• partition key value: 2048 bytes
• sort key value: 1024 bytes

Going over either one is rejected with HTTP 400 ValidationException:

One or more parameter values were invalid: Size of hashkey has exceeded the maximum size limit of 2048 bytes

See https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ServiceQuotas.html#limits-partition-sort-keys

AWS-published DynamoDB Local 3.3.1 enforces both limits.

Actual behavior

Floci accepts oversized keys and stores the item. No error, and the item shows up in a later Scan.

This matters for tests that check how an application handles a non-retryable DynamoDB error. A common way to trigger one is to write a key that is too long. Against Floci the write succeeds, so the test passes for the wrong reason or fails because no error arrives.

Reproduction

# partition key: 2100 bytes, limit is 2048
aws dynamodb create-table --table-name repro-keysize \
  --attribute-definitions AttributeName=pk,AttributeType=S \
  --key-schema AttributeName=pk,KeyType=HASH \
  --billing-mode PAY_PER_REQUEST
aws dynamodb wait table-exists --table-name repro-keysize

BIG=$(printf "x%.0s" $(seq 1 2100))
aws dynamodb put-item --table-name repro-keysize --item "{\"pk\":{\"S\":\"$BIG\"}}"
aws dynamodb scan --table-name repro-keysize --select COUNT --query Count --output text

Real AWS and DynamoDB Local: ValidationException.
Floci: exit code 0, and the scan returns 1.

The sort key behaves the same way:

# sort key: 1100 bytes, limit is 1024
aws dynamodb create-table --table-name repro-sk \
  --attribute-definitions AttributeName=pk,AttributeType=S AttributeName=sk,AttributeType=S \
  --key-schema AttributeName=pk,KeyType=HASH AttributeName=sk,KeyType=RANGE \
  --billing-mode PAY_PER_REQUEST
aws dynamodb wait table-exists --table-name repro-sk

SK=$(printf "y%.0s" $(seq 1 1100))
aws dynamodb put-item --table-name repro-sk --item "{\"pk\":{\"S\":\"a\"},\"sk\":{\"S\":\"$SK\"}}"
aws dynamodb scan --table-name repro-sk --select COUNT --query Count --output text

Same result: accepted and stored.

Environment

• Floci version / image tag: 2.0.1, floci/floci:latest (sha256:4e451c39c7bb88e3cd4f87e8fc0c25d5b47695a51185d521e2241fa00486e8eb)
• Java SDK version (if applicable): n/a, reproduced with AWS CLI v2 and @aws-sdk/client-dynamodb v3
• How you're running Floci: Docker, via docker compose