Streaming Queries

For large result sets, use streaming to process rows one at a time without loading everything into memory.

Basic Streaming

await using stream = await cn.queryStream<{ id: number; name: string }>(
  "SELECT id, name FROM LargeTable",
);

for await (const row of stream) {
  console.log(row.id, row.name);
}

Pool Streaming

When using a pool, the connection is automatically acquired and released:

await using stream = await pool.queryStream<{ id: number }>(
  "SELECT id FROM LargeTable WHERE status = @status",
  { status: "active" },
);

for await (const row of stream) {
  process(row);
}
// Connection released when stream closes

Early Exit

You can break out of the stream early:

await using stream = await cn.queryStream<{ id: number }>(
  "SELECT id FROM BigTable",
);

for await (const row of stream) {
  if (row.id > 100) break;
}
// Stream is automatically closed

Stream Utility Methods

QueryStream provides several convenience methods:

// Collect all rows
const rows = await stream.toArray();

// Transform rows
const names = await stream.map((row) => row.name);

// Filter rows
const active = await stream.filter((row) => row.active);

// Reduce without collecting
const total = await stream.reduce((sum, row) => sum + row.amount, 0);

// Convert to standard ReadableStream
const readable = stream.toReadableStream();

// Pipe to WritableStream
await stream.pipeTo(writableStream);