Struct StreamingJSONWriter 

pub struct StreamingJSONWriter<W: Write> { /* private fields */ }

Streaming JSON writer for memory-efficient export of large datasets

Outputs a JSON array with one object per row. Unlike the batch JSONWriter, this writer processes data incrementally, allowing export of arbitrarily large result sets within memory constraints.

Output Format

[
  {"col1": "value1", "col2": 123},
  {"col1": "value2", "col2": 456}
]

Example

let file = File::create("output.json")?;
let mut writer = StreamingJSONWriter::new(file);

writer.write_header(&metadata)?;

for chunk in result_iterator.chunks(10_000) {
    writer.write_chunk(&chunk)?;
}

writer.finalize()?;

Implementations

impl<W: Write> StreamingJSONWriter<W>

pub fn new(output: W) -> Self

Create a new streaming JSON writer with pretty-printing

pub fn compact(output: W) -> Self

Create with compact (non-pretty) output

Trait Implementations

impl<W: Write + Send> StreamingWriter for StreamingJSONWriter<W>

fn write_header(&mut self, metadata: &QueryMetadata) -> Result<(), OutputError>

Initialize writer with column metadata (write header if applicable)

fn write_chunk(&mut self, rows: &[QueryRow]) -> Result<usize, OutputError>

Write a chunk of rows (called multiple times during streaming)

fn finalize(&mut self) -> Result<(), OutputError>

Finalize output (flush buffers, write footer, close resources)

fn rows_written(&self) -> u64

Get count of rows written so far

fn bytes_written(&self) -> Option<u64>

Get bytes written so far (if trackable)