HackPoint commented on PR #44783:
URL: https://github.com/apache/arrow/pull/44783#issuecomment-3096746066
> One thing I didn't do was to resolve the question of the unused
`_dataSetSchema` and `_parameterSchema` fields on `PreparedStatement`. Work is
being done to populate these, but they are never used. I started removing them
but then realized that I don't really understand the difference between these
and the `GetSchemaAsync` call on the same class. Can you take another look and
decide what you think should be done about this?
After reviewing the C++ implementation (client.h / PreparedStatement), I
confirmed that:
```cpp
std::shared_ptr<Schema> parameter_schema() const { return parameter_schema_;
}
std::shared_ptr<Schema> dataset_schema() const { return dataset_schema_; }
```
source: `[client.h / PreparedStatement]`
These schemas are accessed directly by consumers after creating the prepared
statement, allowing them to inspect the expected input/output without making
additional calls.
In contrast, `GetSchemaAsync()` in C# makes a separate server call to
retrieve the schema again — which may be redundant if we already have it.
So I made the design decision to expose both schemas as public, readonly
properties:
```csharp
public Schema DatasetSchema { get; }
public Schema ParameterSchema { get; }
```
This aligns with the C++ API and gives clients immediate access to the known
schemas without having to re-fetch them. If schema refresh is ever required,
they can still call `GetSchemaAsync()` manually.
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