Trait StreamingWriteSource

Source

pub trait StreamingWriteSource: Send {
    // Required methods
    fn arrow_schema(&self) -> SchemaRef;
    fn into_stream(self) -> SendableRecordBatchStream;

    // Provided method
    fn into_stream_and_schema<'async_trait>(
        self,
    ) -> Pin<Box<dyn Future<Output = Result<(SendableRecordBatchStream, Schema)>> + Send + 'async_trait>>
       where Self: Sized + 'async_trait { ... }
}

Expand description

A trait for [BatchRecord] iterators, readers and streams that can be converted to a concrete stream type SendableRecordBatchStream.

This also cam read the schema from the first batch and then update the schema to reflect the dictionary columns.

Required Methods§

Source

fn arrow_schema(&self) -> SchemaRef

Returns the arrow schema.

Source

fn into_stream(self) -> SendableRecordBatchStream

Convert to a stream.

The conversion will be conducted in a background thread.

Provided Methods§

Source

fn into_stream_and_schema<'async_trait>( self, ) -> Pin<Box<dyn Future<Output = Result<(SendableRecordBatchStream, Schema)>> + Send + 'async_trait>>
where Self: Sized + 'async_trait,

Infer the Lance schema from the first batch stream.

This will peek the first batch to get the dictionaries for dictionary columns.

NOTE: this does not validate the schema. For example, for appends the schema should be checked to make sure it matches the existing dataset schema before writing.