Stream rows and stop early

Choose stream when callers should process rows as they arrive rather than buffer the complete result. Pass a cancellable context and check every yielded error.

Generate a streaming method

Use the stream command on a row-returning query:

-- sgl.query(StreamReadings, stream)
SELECT taken_at, level_cm FROM readings ORDER BY taken_at;

Run sgl vet and sgl generate. The method returns a range-over-func iterator instead of a slice.

Process each row and stop when ready

Range over the iterator, checking the error before using its row. This example stops as soon as the level reaches the flood-warning threshold:

	read := 0
	for reading, err := range queries.StreamReadings(ctx) {
		if err != nil {
			return fmt.Errorf("streaming readings: %w", err)
		}
		read++
		if reading.LevelCm >= floodWarningCm {
			fmt.Fprintf(output, "flood warning at %s, %dcm, after reading %d of %d rows\n", reading.TakenAt, reading.LevelCm, read, count)
			break
		}
	}

Breaking or returning from the loop closes the rows. Let the context expire or cancel it when the surrounding request no longer needs the query.

A database or scan error can arrive after earlier rows have been consumed. If the loop yields an error, report a failed or partial operation rather than treating the rows seen so far as the complete result.

See the query commands reference for the generated signature. The example also scans every reading to compute the high-water mark; its test checks both complete and early-stop paths.

The working example includes connection setup and tests. From the repository root, run:

cd examples/sqlite/017_streaming
go test .