Bolt プロトコルを使用したクエリ結果のストリーミング

static void processBatches(Result result, int size,
        Consumer<List<Record>> handler) {
    var batch = new ArrayList<Record>();
    while (result.hasNext()) {
        batch.add(result.next());
        if (batch.size() >= size) {
            handler.accept(batch);
            batch = new ArrayList<>();
        }
    }
    if (!batch.isEmpty()) handler.accept(batch);
}

// Usage:
try (Session session = driver.session(SessionConfig.builder()
        .withFetchSize(50)
        .withDefaultAccessMode(AccessMode.READ)
        .build())) {

    Result result = session.run("MATCH (m:movie) RETURN m.title AS title");
    processBatches(result, 10, batch -> {
        for (var record : batch) {
            System.out.println(record.get("title").asString());
        }

        // Do other intermediary work here between batch calls
    });
    result.consume();
}

async def batched(result, size):
    batch = []
    async for record in result:
        batch.append(record)
        if len(batch) >= size:
            yield batch
            batch = []
    if batch:
        yield batch

# Usage:
async with driver.session(fetch_size=50) as session:
    result = await session.run("MATCH (m:movie) RETURN m.title AS title")
    async for batch in batched(result, 10):
        for record in batch:
            print(record["title"])

        # Do other intermediary work here between batch calls

func processBatches(ctx context.Context, result neo4j.ResultWithContext,
        size int, handler func([]*neo4j.Record)) error {
    var batch []*neo4j.Record
    for result.Next(ctx) {
        batch = append(batch, result.Record())
        if len(batch) >= size {
            handler(batch)
            batch = nil
        }
    }
    if len(batch) > 0 {
        handler(batch)
    }
    return result.Err()
}

// Usage:
session := driver.NewSession(ctx, neo4j.SessionConfig{
    AccessMode: neo4j.AccessModeRead,
    FetchSize:  50,
})
defer session.Close(ctx)

result, err := session.Run(ctx,
    "MATCH (m:movie) RETURN m.title AS title", nil)
if err != nil {
    log.Fatal(err)
}

if err := processBatches(ctx, result, 10, func(batch []*neo4j.Record) {
    for _, record := range batch {
        title, _ := record.Get("title")
        fmt.Println(title)
    }

    // Do other intermediary work here between batch calls
}); err != nil {
    log.Fatal(err)
}

static async IAsyncEnumerable<List<IRecord>> Batched(
        IResultCursor result, int size)
{
    var batch = new List<IRecord>();
    while (await result.FetchAsync())
    {
        batch.Add(result.Current);
        if (batch.Count >= size)
        {
            yield return batch;
            batch = new List<IRecord>();
        }
    }
    if (batch.Count > 0) yield return batch;
}

// Usage:
await using var session = driver.AsyncSession(o => o
    .WithFetchSize(50)
    .WithDefaultAccessMode(AccessMode.Read));

var result = await session.RunAsync("MATCH (m:movie) RETURN m.title AS title");
await foreach (var batch in Batched(result, 10))
{
    foreach (var record in batch)
    {
        Console.WriteLine(record["title"].As<string>());
    }

    // Do other intermediary work here between batch calls
}

// Uses for-await-of on the Result's async iterator (Neo4j driver v5+).
// This is pull-based: the driver pauses fetching while the loop body
// executes, providing natural backpressure. This is preferred over
// result.subscribe(), which is push-based and continues delivering
// records during async processing.
async function* batched(result, size) {
    let batch = [];
    for await (const record of result) {
        batch.push(record);
        if (batch.length >= size) {
            yield batch;
            batch = [];
        }
    }
    if (batch.length > 0) yield batch;
}

// Usage:
const session = driver.session({
    defaultAccessMode: neo4j.session.READ,
    fetchSize: 50
});

try {
    const result = session.run('MATCH (m:movie) RETURN m.title AS title');
    for await (const batch of batched(result, 10)) {
        for (const record of batch) {
            console.log(record.get('title'));
        }

        // Do other intermediary work here between batch calls
    }
} finally {
    await session.close();
}