samples/snippets/standard/data/sqlite/AsyncSample/Program.cs - main - aprogrammer/dotnet-docs

samples/snippets/standard/data/sqlite/AsyncSample/Program.cs

67 строк2 KB

compujuckel

sqlite: do not recommend usage of shared cache (#35584)

06 июн 2023, 19:34

06 июн 2023, 19:34ef04c3c

using System;
using System.Diagnostics;
using System.IO;
using System.Threading.Tasks;
using Microsoft.Data.Sqlite;

namespace AsyncSample
{
    class Program
    {
        static async Task Main()
        {
            // SQLite doesn't support asynchronous I/O. Instead, they recommend using a
            // write-ahead log (WAL) which improves write performance. This sample
            // demonstrates the anti-pattern of using ADO.NET's async methods with
            // Microsoft.Data.Sqlite.

            #region snippet_WAL
            var connection = new SqliteConnection("Data Source=AsyncSample.db");
            connection.Open();

            // Enable write-ahead logging
            var walCommand = connection.CreateCommand();
            walCommand.CommandText =
            @"
                PRAGMA journal_mode = 'wal'
            ";
            walCommand.ExecuteNonQuery();
            #endregion

            var createCommand = connection.CreateCommand();
            createCommand.CommandText =
            @"
                CREATE TABLE data (
                    value BLOB
                )
            ";
            createCommand.ExecuteNonQuery();

            var insertCommand = connection.CreateCommand();
            insertCommand.CommandText =
            @"
                INSERT INTO data
                VALUES ($value)
            ";

            Console.WriteLine("Generating 100 MB of data...");
            var value = new byte[100_000_000];
            var random = new Random();
            random.NextBytes(value);
            insertCommand.Parameters.AddWithValue("$value", value);

            Console.WriteLine("Inserting data...");
            var stopwatch = Stopwatch.StartNew();
            var task = insertCommand.ExecuteNonQueryAsync();
            Console.WriteLine($"Blocked for {stopwatch.ElapsedMilliseconds} ms");

            stopwatch.Restart();
            await task;
            Console.WriteLine($"Yielded for {stopwatch.ElapsedMilliseconds} ms");

            // Clean up
            connection.Close();
            File.Delete("AsyncSample.db");
        }
    }
}