Type Alias SchemaFieldMetadata 

pub type SchemaFieldMetadata = HashMap<String, String>;

The metadata used in Field::metadata.

This represents the metadata associated with an Arrow Field. The metadata consists of key-value pairs.

Common Use Cases

Field metadata is commonly used to store:

• Default values for columns when data is missing
• Column descriptions or documentation
• Data lineage information
• Custom application-specific annotations
• Encoding hints or display formatting preferences

Example: Storing Default Values

A practical example of using field metadata is storing default values for columns that may be missing in the physical data but present in the logical schema. See the default_column_values.rs example implementation.

Aliased Type

pub struct SchemaFieldMetadata { /* private fields */ }