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# SDK for .NET (v4) を使用した CloudWatch Logs の例
<a name="csharp_4_cloudwatch-logs_code_examples"></a>

次のコード例は、CloudWatch Logs で AWS SDK for .NET (v4) を使用してアクションを実行し、一般的なシナリオを実装する方法を示しています。

*アクション*はより大きなプログラムからのコードの抜粋であり、コンテキスト内で実行する必要があります。アクションは個々のサービス機能を呼び出す方法を示していますが、コンテキスト内のアクションは、関連するシナリオで確認できます。

*シナリオ*は、1 つのサービス内から、または他の AWS のサービスと組み合わせて複数の関数を呼び出し、特定のタスクを実行する方法を示すコード例です。

各例には完全なソースコードへのリンクが含まれており、コードの設定方法と実行方法に関する手順を確認できます。

**Topics**
+ [アクション](#actions)
+ [シナリオ](#scenarios)

## アクション
<a name="actions"></a>

### `GetQueryResults`
<a name="cloudwatch-logs_GetQueryResults_csharp_4_topic"></a>

次の例は、`GetQueryResults` を使用する方法を説明しています。

**SDK for .NET (v4)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/dotnetv4/CloudWatchLogs/LargeQuery#code-examples)での設定と実行の方法を確認してください。

```
    /// <summary>
    /// Gets the results of a CloudWatch Logs Insights query.
    /// </summary>
    /// <param name="queryId">The ID of the query.</param>
    /// <returns>The query results response.</returns>
    public async Task<GetQueryResultsResponse?> GetQueryResultsAsync(string queryId)
    {
        try
        {
            var request = new GetQueryResultsRequest
            {
                QueryId = queryId
            };

            var response = await _amazonCloudWatchLogs.GetQueryResultsAsync(request);
            return response;
        }
        catch (ResourceNotFoundException ex)
        {
            _logger.LogError($"Query not found: {ex.Message}");
            return null;
        }
        catch (Exception ex)
        {
            _logger.LogError($"An error occurred while getting query results: {ex.Message}");
            return null;
        }
    }
```
+  API の詳細については、「**AWS SDK for .NET API リファレンス」の「[GetQueryResults](https://docs.aws.amazon.com/goto/DotNetSDKV4/logs-2014-03-28/GetQueryResults)」を参照してください。

### `StartQuery`
<a name="cloudwatch-logs_StartQuery_csharp_4_topic"></a>

次の例は、`StartQuery` を使用する方法を説明しています。

**SDK for .NET (v4)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/dotnetv4/CloudWatchLogs/LargeQuery#code-examples)での設定と実行の方法を確認してください。

```
    /// <summary>
    /// Starts a CloudWatch Logs Insights query.
    /// </summary>
    /// <param name="logGroupName">The name of the log group to query.</param>
    /// <param name="queryString">The CloudWatch Logs Insights query string.</param>
    /// <param name="startTime">The start time for the query (seconds since epoch).</param>
    /// <param name="endTime">The end time for the query (seconds since epoch).</param>
    /// <param name="limit">The maximum number of results to return.</param>
    /// <returns>The query ID if successful, null otherwise.</returns>
    public async Task<string?> StartQueryAsync(
        string logGroupName,
        string queryString,
        long startTime,
        long endTime,
        int limit = 10000)
    {
        try
        {
            var request = new StartQueryRequest
            {
                LogGroupName = logGroupName,
                QueryString = queryString,
                StartTime = startTime,
                EndTime = endTime,
                Limit = limit
            };

            var response = await _amazonCloudWatchLogs.StartQueryAsync(request);
            return response.QueryId;
        }
        catch (InvalidParameterException ex)
        {
            _logger.LogError($"Invalid parameter for query: {ex.Message}");
            return null;
        }
        catch (ResourceNotFoundException ex)
        {
            _logger.LogError($"Log group not found: {ex.Message}");
            return null;
        }
        catch (Exception ex)
        {
            _logger.LogError($"An error occurred while starting query: {ex.Message}");
            return null;
        }
    }
```
+  API の詳細については、「**AWS SDK for .NET API リファレンス」の「[StartQuery](https://docs.aws.amazon.com/goto/DotNetSDKV4/logs-2014-03-28/StartQuery)」を参照してください。

## シナリオ
<a name="scenarios"></a>

### 大規模なクエリを実行する
<a name="cloudwatch-logs_Scenario_BigQuery_csharp_4_topic"></a>

次のコード例は、CloudWatch Logs を使用して 10,000 を超えるレコードをクエリする方法を示しています。

**SDK for .NET (v4)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/dotnetv4/CloudWatchLogs/LargeQuery#code-examples)での設定と実行の方法を確認してください。
これは、大規模なクエリシナリオを示すメインワークフローです。  

```
using System.Diagnostics;
using System.Text.RegularExpressions;
using Amazon.CloudFormation;
using Amazon.CloudFormation.Model;
using Amazon.CloudWatchLogs;
using Amazon.CloudWatchLogs.Model;
using CloudWatchLogsActions;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace CloudWatchLogsScenario;

public class LargeQueryWorkflow
{
    /*
    Before running this .NET code example, set up your development environment, including your credentials.
    This .NET code example performs the following tasks for the CloudWatch Logs Large Query workflow:

    1. Prepare the Application:
       - Prompt the user to deploy CloudFormation stack and generate sample logs.
       - Deploy the CloudFormation template for resource creation.
       - Generate 50,000 sample log entries using CloudWatch Logs API.
       - Wait 5 minutes for logs to be fully ingested.

    2. Execute Large Query:
       - Perform recursive queries to retrieve all logs using binary search.
       - Display progress for each query executed.
       - Show total execution time and logs found.

    3. Clean up:
       - Prompt the user to delete the CloudFormation stack and all resources.
       - Destroy the CloudFormation stack and wait until removed.
    */

    public static ILogger<LargeQueryWorkflow> _logger = null!;
    public static CloudWatchLogsWrapper _wrapper = null!;
    public static IAmazonCloudFormation _amazonCloudFormation = null!;

    private static string _logGroupName = "/workflows/cloudwatch-logs/large-query";
    private static string _logStreamName = "stream1";
    private static long _queryStartDate;
    private static long _queryEndDate;

    public static bool _interactive = true;
    public static string _stackName = "CloudWatchLargeQueryStack";
    private static string _stackResourcePath = "../../../../../../../scenarios/features/cloudwatch_logs_large_query/resources/stack.yaml";

    public static async Task Main(string[] args)
    {
        using var host = Host.CreateDefaultBuilder(args)
            .ConfigureLogging(logging =>
                logging.AddFilter("System", LogLevel.Debug)
                    .AddFilter("Microsoft", LogLevel.Information))
            .ConfigureServices((_, services) =>
                services.AddAWSService<IAmazonCloudWatchLogs>()
                    .AddAWSService<IAmazonCloudFormation>()
                    .AddTransient<CloudWatchLogsWrapper>()
            )
            .Build();

        if (_interactive)
        {
            _logger = LoggerFactory.Create(builder => { builder.AddConsole(); })
                .CreateLogger<LargeQueryWorkflow>();

            _wrapper = host.Services.GetRequiredService<CloudWatchLogsWrapper>();
            _amazonCloudFormation = host.Services.GetRequiredService<IAmazonCloudFormation>();
        }

        Console.WriteLine(new string('-', 80));
        Console.WriteLine("Welcome to the CloudWatch Logs Large Query Scenario.");
        Console.WriteLine(new string('-', 80));
        Console.WriteLine("This scenario demonstrates how to perform large-scale queries on");
        Console.WriteLine("CloudWatch Logs using recursive binary search to retrieve more than");
        Console.WriteLine("the 10,000 result limit.");
        Console.WriteLine();

        try
        {
            Console.WriteLine(new string('-', 80));
            var prepareSuccess = await PrepareApplication();
            Console.WriteLine(new string('-', 80));

            if (prepareSuccess)
            {
                Console.WriteLine(new string('-', 80));
                await ExecuteLargeQuery();
                Console.WriteLine(new string('-', 80));
            }

            Console.WriteLine(new string('-', 80));
            await Cleanup();
            Console.WriteLine(new string('-', 80));
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "There was a problem with the scenario, initiating cleanup...");
            _interactive = false;
            await Cleanup();
        }

        Console.WriteLine("CloudWatch Logs Large Query scenario completed.");
    }

    /// <summary>
    /// Runs the scenario workflow. Used for testing.
    /// </summary>
    public static async Task RunScenario()
    {
        Console.WriteLine(new string('-', 80));
        Console.WriteLine("Welcome to the CloudWatch Logs Large Query Scenario.");
        Console.WriteLine(new string('-', 80));
        Console.WriteLine("This scenario demonstrates how to perform large-scale queries on");
        Console.WriteLine("CloudWatch Logs using recursive binary search to retrieve more than");
        Console.WriteLine("the 10,000 result limit.");
        Console.WriteLine();

        try
        {
            Console.WriteLine(new string('-', 80));
            var prepareSuccess = await PrepareApplication();
            Console.WriteLine(new string('-', 80));

            if (prepareSuccess)
            {
                Console.WriteLine(new string('-', 80));
                await ExecuteLargeQuery();
                Console.WriteLine(new string('-', 80));
            }

            Console.WriteLine(new string('-', 80));
            await Cleanup();
            Console.WriteLine(new string('-', 80));
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "There was a problem with the scenario, initiating cleanup...");
            _interactive = false;
            await Cleanup();
        }

        Console.WriteLine("CloudWatch Logs Large Query scenario completed.");
    }

    /// <summary>
    /// Prepares the application by creating the necessary resources.
    /// </summary>
    /// <returns>True if the application was prepared successfully.</returns>
    public static async Task<bool> PrepareApplication()
    {
        Console.WriteLine("Preparing the application...");
        Console.WriteLine();

        try
        {
            var deployStack = !_interactive || GetYesNoResponse(
                "Would you like to deploy the CloudFormation stack and generate sample logs? (y/n) ");

            if (deployStack)
            {
                if (_interactive)
                {
                    Console.Write(
                        $"Enter a path for the CloudFormation stack resource .yaml file (or press Enter for default '{_stackResourcePath}'): ");
                    string? inputPath = Console.ReadLine();
                    if (!string.IsNullOrWhiteSpace(inputPath))
                    {
                        _stackResourcePath = inputPath;
                    }
                }

                _stackName = PromptUserForStackName();

                var deploySuccess = await DeployCloudFormationStack(_stackName);

                if (deploySuccess)
                {
                    Console.WriteLine();
                    Console.WriteLine("Generating 50,000 sample log entries...");
                    var generateSuccess = await GenerateSampleLogs();

                    if (generateSuccess)
                    {
                        Console.WriteLine();
                        Console.WriteLine("Sample logs created. Waiting 5 minutes for logs to be fully ingested...");
                        await WaitWithCountdown(300);

                        Console.WriteLine("Application preparation complete.");
                        return true;
                    }
                }
            }
            else
            {
                _logGroupName = PromptUserForInput("Enter the log group name ", _logGroupName);
                _logStreamName = PromptUserForInput("Enter the log stream name ", _logStreamName);

                var startDateMs = PromptUserForLong("Enter the query start date (milliseconds since epoch): ");
                var endDateMs = PromptUserForLong("Enter the query end date (milliseconds since epoch): ");

                _queryStartDate = startDateMs / 1000;
                _queryEndDate = endDateMs / 1000;

                Console.WriteLine("Application preparation complete.");
                return true;
            }
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "An error occurred while preparing the application.");
        }

        Console.WriteLine("Application preparation failed.");
        return false;
    }

    /// <summary>
    /// Deploys the CloudFormation stack with the necessary resources.
    /// </summary>
    /// <param name="stackName">The name of the CloudFormation stack.</param>
    /// <returns>True if the stack was deployed successfully.</returns>
    private static async Task<bool> DeployCloudFormationStack(string stackName)
    {
        Console.WriteLine($"\nDeploying CloudFormation stack: {stackName}");

        try
        {
            var request = new CreateStackRequest
            {
                StackName = stackName,
                TemplateBody = await File.ReadAllTextAsync(_stackResourcePath)
            };

            var response = await _amazonCloudFormation.CreateStackAsync(request);

            if (response.HttpStatusCode == System.Net.HttpStatusCode.OK)
            {
                Console.WriteLine($"CloudFormation stack creation started: {stackName}");

                bool stackCreated = await WaitForStackCompletion(response.StackId);

                if (stackCreated)
                {
                    Console.WriteLine("CloudFormation stack created successfully.");
                    return true;
                }
                else
                {
                    _logger.LogError($"CloudFormation stack creation failed: {stackName}");
                    return false;
                }
            }
            else
            {
                _logger.LogError($"Failed to create CloudFormation stack: {stackName}");
                return false;
            }
        }
        catch (AlreadyExistsException)
        {
            _logger.LogWarning($"CloudFormation stack '{stackName}' already exists. Please provide a unique name.");
            var newStackName = PromptUserForStackName();
            return await DeployCloudFormationStack(newStackName);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, $"An error occurred while deploying the CloudFormation stack: {stackName}");
            return false;
        }
    }

    /// <summary>
    /// Waits for the CloudFormation stack to be in the CREATE_COMPLETE state.
    /// </summary>
    /// <param name="stackId">The ID of the CloudFormation stack.</param>
    /// <returns>True if the stack was created successfully.</returns>
    private static async Task<bool> WaitForStackCompletion(string stackId)
    {
        int retryCount = 0;
        const int maxRetries = 30;
        const int retryDelay = 10000;

        while (retryCount < maxRetries)
        {
            var describeStacksRequest = new DescribeStacksRequest
            {
                StackName = stackId
            };

            var describeStacksResponse = await _amazonCloudFormation.DescribeStacksAsync(describeStacksRequest);

            if (describeStacksResponse.Stacks.Count > 0)
            {
                if (describeStacksResponse.Stacks[0].StackStatus == StackStatus.CREATE_COMPLETE)
                {
                    return true;
                }
                if (describeStacksResponse.Stacks[0].StackStatus == StackStatus.CREATE_FAILED ||
                    describeStacksResponse.Stacks[0].StackStatus == StackStatus.ROLLBACK_COMPLETE)
                {
                    return false;
                }
            }

            Console.WriteLine("Waiting for CloudFormation stack creation to complete...");
            await Task.Delay(retryDelay);
            retryCount++;
        }

        _logger.LogError("Timed out waiting for CloudFormation stack creation to complete.");
        return false;
    }

    /// <summary>
    /// Generates sample logs directly using CloudWatch Logs API.
    /// Creates 50,000 log entries spanning 5 minutes.
    /// </summary>
    /// <returns>True if logs were generated successfully.</returns>
    private static async Task<bool> GenerateSampleLogs()
    {
        const int totalEntries = 50000;
        const int entriesPerBatch = 10000;
        const int fiveMinutesMs = 5 * 60 * 1000;

        try
        {
            // Calculate timestamps
            var startTimeMs = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
            var timestampIncrement = fiveMinutesMs / totalEntries;

            Console.WriteLine($"Generating {totalEntries} log entries...");

            var entryCount = 0;
            var currentTimestamp = startTimeMs;
            var numBatches = totalEntries / entriesPerBatch;

            // Generate and upload logs in batches
            for (int batchNum = 0; batchNum < numBatches; batchNum++)
            {
                var logEvents = new List<InputLogEvent>();

                for (int i = 0; i < entriesPerBatch; i++)
                {
                    logEvents.Add(new InputLogEvent
                    {
                        Timestamp = DateTimeOffset.FromUnixTimeMilliseconds(currentTimestamp).UtcDateTime,
                        Message = $"Entry {entryCount}"
                    });

                    entryCount++;
                    currentTimestamp += timestampIncrement;
                }

                // Upload batch
                var success = await _wrapper.PutLogEventsAsync(_logGroupName, _logStreamName, logEvents);
                if (!success)
                {
                    _logger.LogError($"Failed to upload batch {batchNum + 1}/{numBatches}");
                    return false;
                }

                Console.WriteLine($"Uploaded batch {batchNum + 1}/{numBatches}");
            }

            // Set query date range (convert milliseconds to seconds for query API)
            _queryStartDate = startTimeMs / 1000;
            _queryEndDate = (currentTimestamp - timestampIncrement) / 1000;

            Console.WriteLine($"Query start date: {DateTimeOffset.FromUnixTimeSeconds(_queryStartDate):yyyy-MM-ddTHH:mm:ss.fffZ}");
            Console.WriteLine($"Query end date: {DateTimeOffset.FromUnixTimeSeconds(_queryEndDate):yyyy-MM-ddTHH:mm:ss.fffZ}");
            Console.WriteLine($"Successfully uploaded {totalEntries} log entries");

            return true;
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "An error occurred while generating sample logs.");
            return false;
        }
    }

    /// <summary>
    /// Executes the large query workflow.
    /// </summary>
    public static async Task ExecuteLargeQuery()
    {
        Console.WriteLine("Starting recursive query to retrieve all logs...");
        Console.WriteLine();

        var queryLimit = PromptUserForInteger("Enter the query limit (max 10000) ", 10000);
        if (queryLimit > 10000) queryLimit = 10000;

        var queryString = "fields @timestamp, @message | sort @timestamp asc";

        var stopwatch = Stopwatch.StartNew();
        var allResults = await PerformLargeQuery(_logGroupName, queryString, _queryStartDate, _queryEndDate, queryLimit);
        stopwatch.Stop();

        Console.WriteLine();
        Console.WriteLine($"Queries finished in {stopwatch.Elapsed.TotalSeconds:F3} seconds.");
        Console.WriteLine($"Total logs found: {allResults.Count}");

        // Check for duplicates
        Console.WriteLine();
        Console.WriteLine("Checking for duplicate logs...");
        var duplicates = FindDuplicateLogs(allResults);
        if (duplicates.Count > 0)
        {
            Console.WriteLine($"WARNING: Found {duplicates.Count} duplicate log entries!");
            Console.WriteLine("Duplicate entries (showing first 10):");
            foreach (var dup in duplicates.Take(10))
            {
                Console.WriteLine($"  [{dup.Timestamp}] {dup.Message} (appears {dup.Count} times)");
            }

            var uniqueCount = allResults.Count - duplicates.Sum(d => d.Count - 1);
            Console.WriteLine($"Unique logs: {uniqueCount}");
        }
        else
        {
            Console.WriteLine("No duplicates found. All logs are unique.");
        }
        Console.WriteLine();

        var viewSample = !_interactive || GetYesNoResponse("Would you like to see a sample of the logs? (y/n) ");
        if (viewSample)
        {
            Console.WriteLine();
            Console.WriteLine($"Sample logs (first 10 of {allResults.Count}):");
            for (int i = 0; i < Math.Min(10, allResults.Count); i++)
            {
                var timestamp = allResults[i].Find(f => f.Field == "@timestamp")?.Value ?? "N/A";
                var message = allResults[i].Find(f => f.Field == "@message")?.Value ?? "N/A";
                Console.WriteLine($"[{timestamp}] {message}");
            }
        }
    }

    /// <summary>
    /// Performs a large query using recursive binary search.
    /// </summary>
    private static async Task<List<List<ResultField>>> PerformLargeQuery(
        string logGroupName,
        string queryString,
        long startTime,
        long endTime,
        int limit)
    {
        var queryId = await _wrapper.StartQueryAsync(logGroupName, queryString, startTime, endTime, limit);
        if (queryId == null)
        {
            return new List<List<ResultField>>();
        }

        var results = await PollQueryResults(queryId);
        if (results == null || results.Count == 0)
        {
            return new List<List<ResultField>>();
        }

        var startDate = DateTimeOffset.FromUnixTimeSeconds(startTime).ToString("yyyy-MM-ddTHH:mm:ss.fffZ");
        var endDate = DateTimeOffset.FromUnixTimeSeconds(endTime).ToString("yyyy-MM-ddTHH:mm:ss.fffZ");
        Console.WriteLine($"Query date range: {startDate} ({startTime}s) to {endDate} ({endTime}s). Found {results.Count} logs.");

        if (results.Count < limit)
        {
            Console.WriteLine($"  -> Returning {results.Count} logs (less than limit of {limit})");
            return results;
        }

        Console.WriteLine($"  -> Hit limit of {limit}. Need to split and recurse.");

        // Get the timestamp of the last log (sorted to find the actual last one)
        var lastLogTimestamp = GetLastLogTimestamp(results);
        if (lastLogTimestamp == null)
        {
            Console.WriteLine($"  -> No timestamp found in results. Returning {results.Count} logs.");
            return results;
        }

        Console.WriteLine($"  -> Last log timestamp: {lastLogTimestamp}");

        // Parse the timestamp and add 1 millisecond to avoid querying the same log again
        var lastLogDate = DateTimeOffset.Parse(lastLogTimestamp + " +0000");
        Console.WriteLine($"  -> Last log as DateTimeOffset: {lastLogDate:yyyy-MM-ddTHH:mm:ss.fffZ} ({lastLogDate.ToUnixTimeSeconds()}s)");

        var offsetLastLogDate = lastLogDate.AddMilliseconds(1);
        Console.WriteLine($"  -> Offset timestamp (last + 1ms): {offsetLastLogDate:yyyy-MM-ddTHH:mm:ss.fffZ} ({offsetLastLogDate.ToUnixTimeSeconds()}s)");

        // Convert to seconds, but round UP to the next second to avoid overlapping with logs in the same second
        // This ensures we don't re-query logs that share the same second as the last log
        var offsetLastLogTime = offsetLastLogDate.ToUnixTimeSeconds();
        if (offsetLastLogDate.Millisecond > 0)
        {
            offsetLastLogTime++; // Move to the next full second
            Console.WriteLine($"  -> Adjusted to next full second: {offsetLastLogTime}s ({DateTimeOffset.FromUnixTimeSeconds(offsetLastLogTime):yyyy-MM-ddTHH:mm:ss.fffZ})");
        }

        Console.WriteLine($"  -> Comparing: offsetLastLogTime={offsetLastLogTime}s vs endTime={endTime}s");
        Console.WriteLine($"  -> End time as date: {DateTimeOffset.FromUnixTimeSeconds(endTime):yyyy-MM-ddTHH:mm:ss.fffZ}");

        // Check if there's any time range left to query
        if (offsetLastLogTime >= endTime)
        {
            Console.WriteLine($"  -> No time range left to query. Offset time ({offsetLastLogTime}s) >= end time ({endTime}s)");
            return results;
        }

        // Split the remaining date range in half
        var (range1Start, range1End, range2Start, range2End) = SplitDateRange(offsetLastLogTime, endTime);

        var range1StartDate = DateTimeOffset.FromUnixTimeSeconds(range1Start).ToString("yyyy-MM-ddTHH:mm:ss.fffZ");
        var range1EndDate = DateTimeOffset.FromUnixTimeSeconds(range1End).ToString("yyyy-MM-ddTHH:mm:ss.fffZ");
        var range2StartDate = DateTimeOffset.FromUnixTimeSeconds(range2Start).ToString("yyyy-MM-ddTHH:mm:ss.fffZ");
        var range2EndDate = DateTimeOffset.FromUnixTimeSeconds(range2End).ToString("yyyy-MM-ddTHH:mm:ss.fffZ");

        Console.WriteLine($"  -> Splitting remaining range:");
        Console.WriteLine($"     Range 1: {range1StartDate} ({range1Start}s) to {range1EndDate} ({range1End}s)");
        Console.WriteLine($"     Range 2: {range2StartDate} ({range2Start}s) to {range2EndDate} ({range2End}s)");

        // Query both halves recursively
        Console.WriteLine($"  -> Querying range 1...");
        var results1 = await PerformLargeQuery(logGroupName, queryString, range1Start, range1End, limit);
        Console.WriteLine($"  -> Range 1 returned {results1.Count} logs");

        Console.WriteLine($"  -> Querying range 2...");
        var results2 = await PerformLargeQuery(logGroupName, queryString, range2Start, range2End, limit);
        Console.WriteLine($"  -> Range 2 returned {results2.Count} logs");

        // Combine all results
        var allResults = new List<List<ResultField>>(results);
        allResults.AddRange(results1);
        allResults.AddRange(results2);

        Console.WriteLine($"  -> Combined total: {allResults.Count} logs ({results.Count} + {results1.Count} + {results2.Count})");

        return allResults;
    }

    /// <summary>
    /// Gets the timestamp string of the most recent log from a list of logs.
    /// Sorts timestamps to find the actual last one.
    /// </summary>
    private static string? GetLastLogTimestamp(List<List<ResultField>> logs)
    {
        var timestamps = logs
            .Select(log => log.Find(f => f.Field == "@timestamp")?.Value)
            .Where(t => !string.IsNullOrEmpty(t))
            .OrderBy(t => t)
            .ToList();

        if (timestamps.Count == 0)
        {
            return null;
        }

        return timestamps[timestamps.Count - 1];
    }

    /// <summary>
    /// Splits a date range in half.
    /// Range 2 starts at midpoint + 1 second to avoid overlap.
    /// </summary>
    private static (long range1Start, long range1End, long range2Start, long range2End) SplitDateRange(long startTime, long endTime)
    {
        var midpoint = startTime + (endTime - startTime) / 2;
        // Range 2 starts at midpoint + 1 to avoid querying the same second twice
        return (startTime, midpoint, midpoint + 1, endTime);
    }

    /// <summary>
    /// Polls for query results until complete.
    /// </summary>
    private static async Task<List<List<ResultField>>?> PollQueryResults(string queryId)
    {
        int retryCount = 0;
        const int maxRetries = 60;
        const int retryDelay = 1000;

        while (retryCount < maxRetries)
        {
            var response = await _wrapper.GetQueryResultsAsync(queryId);
            if (response == null)
            {
                return null;
            }

            if (response.Status == QueryStatus.Complete)
            {
                return response.Results;
            }

            if (response.Status == QueryStatus.Failed ||
                response.Status == QueryStatus.Cancelled ||
                response.Status == QueryStatus.Timeout ||
                response.Status == QueryStatus.Unknown)
            {
                _logger.LogError($"Query failed with status: {response.Status}");
                return null;
            }

            await Task.Delay(retryDelay);
            retryCount++;
        }

        _logger.LogError("Timed out waiting for query results.");
        return null;
    }

    /// <summary>
    /// Cleans up the resources created during the scenario.
    /// </summary>
    public static async Task<bool> Cleanup()
    {
        var cleanup = !_interactive || GetYesNoResponse(
            "Do you want to delete the CloudFormation stack and all resources? (y/n) ");

        if (cleanup)
        {
            try
            {
                var stackDeleteSuccess = await DeleteCloudFormationStack(_stackName, false);
                return stackDeleteSuccess;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "An error occurred while cleaning up the resources.");
                return false;
            }
        }

        Console.WriteLine($"Resources will remain. Stack name: {_stackName}, Log group: {_logGroupName}");
        _logger.LogInformation("CloudWatch Logs Large Query scenario is complete.");
        return true;
    }

    /// <summary>
    /// Deletes the CloudFormation stack and waits for confirmation.
    /// </summary>
    private static async Task<bool> DeleteCloudFormationStack(string stackName, bool forceDelete)
    {
        var request = new DeleteStackRequest
        {
            StackName = stackName,
        };

        if (forceDelete)
        {
            request.DeletionMode = DeletionMode.FORCE_DELETE_STACK;
        }

        await _amazonCloudFormation.DeleteStackAsync(request);
        Console.WriteLine($"CloudFormation stack '{stackName}' is being deleted. This may take a few minutes.");

        bool stackDeleted = await WaitForStackDeletion(stackName, forceDelete);

        if (stackDeleted)
        {
            Console.WriteLine($"CloudFormation stack '{stackName}' has been deleted.");
            return true;
        }
        else
        {
            _logger.LogError($"Failed to delete CloudFormation stack '{stackName}'.");
            return false;
        }
    }

    /// <summary>
    /// Waits for the stack to be deleted.
    /// </summary>
    private static async Task<bool> WaitForStackDeletion(string stackName, bool forceDelete)
    {
        int retryCount = 0;
        const int maxRetries = 30;
        const int retryDelay = 10000;

        while (retryCount < maxRetries)
        {
            var describeStacksRequest = new DescribeStacksRequest
            {
                StackName = stackName
            };

            try
            {
                var describeStacksResponse = await _amazonCloudFormation.DescribeStacksAsync(describeStacksRequest);

                if (describeStacksResponse.Stacks.Count == 0 ||
                    describeStacksResponse.Stacks[0].StackStatus == StackStatus.DELETE_COMPLETE)
                {
                    return true;
                }

                if (!forceDelete && describeStacksResponse.Stacks[0].StackStatus == StackStatus.DELETE_FAILED)
                {
                    return await DeleteCloudFormationStack(stackName, true);
                }
            }
            catch (AmazonCloudFormationException ex) when (ex.ErrorCode == "ValidationError")
            {
                return true;
            }

            Console.WriteLine($"Waiting for CloudFormation stack '{stackName}' to be deleted...");
            await Task.Delay(retryDelay);
            retryCount++;
        }

        _logger.LogError($"Timed out waiting for CloudFormation stack '{stackName}' to be deleted.");
        return false;
    }

    /// <summary>
    /// Waits with a countdown display.
    /// </summary>
    private static async Task WaitWithCountdown(int seconds)
    {
        for (int i = seconds; i > 0; i--)
        {
            Console.Write($"\rWaiting: {i} seconds remaining...  ");
            await Task.Delay(1000);
        }
        Console.WriteLine("\rWait complete.                      ");
    }

    /// <summary>
    /// Helper method to get a yes or no response from the user.
    /// </summary>
    private static bool GetYesNoResponse(string question)
    {
        Console.WriteLine(question);
        var ynResponse = Console.ReadLine();
        var response = ynResponse != null && ynResponse.Equals("y", StringComparison.InvariantCultureIgnoreCase);
        return response;
    }

    /// <summary>
    /// Prompts the user for a stack name.
    /// </summary>
    private static string PromptUserForStackName()
    {
        if (_interactive)
        {
            Console.Write($"Enter a name for the CloudFormation stack (press Enter for default '{_stackName}'): ");
            string? input = Console.ReadLine();
            if (!string.IsNullOrWhiteSpace(input))
            {
                var regex = "[a-zA-Z][-a-zA-Z0-9]*";
                if (!Regex.IsMatch(input, regex))
                {
                    Console.WriteLine($"Invalid stack name. Using default: {_stackName}");
                    return _stackName;
                }
                return input;
            }
        }
        return _stackName;
    }

    /// <summary>
    /// Prompts the user for input with a default value.
    /// </summary>
    private static string PromptUserForInput(string prompt, string defaultValue)
    {
        if (_interactive)
        {
            Console.Write($"{prompt}(press Enter for default '{defaultValue}'): ");
            string? input = Console.ReadLine();
            return string.IsNullOrWhiteSpace(input) ? defaultValue : input;
        }
        return defaultValue;
    }

    /// <summary>
    /// Prompts the user for an integer value.
    /// </summary>
    private static int PromptUserForInteger(string prompt, int defaultValue)
    {
        if (_interactive)
        {
            Console.Write($"{prompt}(press Enter for default '{defaultValue}'): ");
            string? input = Console.ReadLine();
            if (string.IsNullOrWhiteSpace(input) || !int.TryParse(input, out var result))
            {
                return defaultValue;
            }
            return result;
        }
        return defaultValue;
    }

    /// <summary>
    /// Prompts the user for a long value.
    /// </summary>
    private static long PromptUserForLong(string prompt)
    {
        if (_interactive)
        {
            Console.Write(prompt);
            string? input = Console.ReadLine();
            if (long.TryParse(input, out var result))
            {
                return result;
            }
        }
        return 0;
    }

    /// <summary>
    /// Finds duplicate log entries based on timestamp and message.
    /// </summary>
    private static List<(string Timestamp, string Message, int Count)> FindDuplicateLogs(List<List<ResultField>> logs)
    {
        var logSignatures = new Dictionary<string, int>();

        foreach (var log in logs)
        {
            var timestamp = log.Find(f => f.Field == "@timestamp")?.Value ?? "";
            var message = log.Find(f => f.Field == "@message")?.Value ?? "";
            var signature = $"{timestamp}|{message}";

            if (logSignatures.ContainsKey(signature))
            {
                logSignatures[signature]++;
            }
            else
            {
                logSignatures[signature] = 1;
            }
        }

        return logSignatures
            .Where(kvp => kvp.Value > 1)
            .Select(kvp =>
            {
                var parts = kvp.Key.Split('|');
                return (Timestamp: parts[0], Message: parts[1], Count: kvp.Value);
            })
            .OrderByDescending(x => x.Count)
            .ToList();
    }
}
```
+ API の詳細については、「AWS SDK for .NET API リファレンス**」の以下のトピックを参照してください。
  + [GetQueryResults](https://docs.aws.amazon.com/goto/DotNetSDKV4/logs-2014-03-28/GetQueryResults)
  + [StartQuery](https://docs.aws.amazon.com/goto/DotNetSDKV4/logs-2014-03-28/StartQuery)