Problem Description

When settingautoTopicCreation on namespace policy, the API validation prevents settingdefaultNumPartitions when the topic type isnon-partitioned. This limitation makes the API harder to use and less flexible.

Current behavior:

• SettingdefaultNumPartitions withtopicType="non-partitioned" results in a validation error:"[defaultNumPartitions] is not allowed to be set when the type is non-partition."

Code location:

Use Cases Affected

1. Configuration management: Users managing configurations programmatically or via infrastructure-as-code tools may want to set a default value even for non-partitioned topics, especially if they plan to switch to partitioned topics later.

2. API consistency: The validation requires users to conditionally include/exclude thedefaultNumPartitions field based on topic type, making the API less consistent and more error-prone.

3. Configuration templates: Shared configuration templates or defaults become harder to maintain when they need to conditionally exclude fields.

Proposed Solution

Consider relaxing this validation to allowdefaultNumPartitions to be set (but ignored) whentopicType="non-partitioned". This would:

• Make the API more user-friendly
• Allow for more flexible configuration management
• Maintain backward compatibility (non-partitioned topics would still be created correctly)
• Simplify client code that doesn't need to conditionally set fields

Alternatively, if there's a technical reason this field must not be set, it would be helpful to document this clearly and potentially provide a clearer error message explaining why.

Question

Is this limitation necessary from a technical standpoint, or could it be relaxed to improve API usability?

Environment

• Pulsar version:3.x,4.x
• Component: Admin API / Namespace Policy