1.前言

hi，大家好，我是三合。我是怎么想起写一篇关于数据库快速批量插入的博客的呢？事情起源于我们工作中的一个需求，简单来说，就是有一个定时任务，从数据库里获取大量数据，在应用层面经过处理后再把结果批量插入回到数据库里。这个任务每十分钟执行一次，但是有的时候数据量太大，循环插入数据库的时候会超时，导致任务失败，所以这个时候我就开始研究怎么快速批量插入数据库，因为我们用的数据库是Oracle，所以我首先研究了Oracle的快速批量插入，后面我一想那其他类型的数据库肯定也有这样的需求，于是我在找了很多资料，并且反复实验后，终于完美解决了mysql,sqlServer以及Oracle的快速批量插入，sqlite自身不支持，所以没有sqlite，特地整理成这篇文章，分享给大家。

2.测试前准备

添加一个具有绝大多数类型属性的实体类，用来完整测验批量插入效果,该实体类用于mysql和sqlserver的测试。

public class NullableTable
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    [Key]
    public int Id { get; set; }
    [Description("Int2")]
    public int? Int2 { get; set; }
    [Description("Long2")]
    public long? Long2 { get; set; }

    public float? Float2 { get; set; }
    public double? Double2 { get; set; }

    public decimal? Decimal2 { get; set; }

    [DecimalPrecision(20,4)]
    public decimal? Decimal3 { get; set; }

    public Guid? Guid2 { get; set; }

    public short? Short2 { get; set; }

    public DateTime? DateTime2 { get; set; }

    public bool? Bool2 { get; set; }

    public TimeSpan? TimeSpan2 { get; set; }

    public byte? Byte2 { get; set; }


    [StringLength(100)]
    public string String2 { get; set; }
    public string String3 { get; set; }

    public Enum2? Enum2 { get; set; }

    [Column("TestInt3")]
    [Description("Int2")]
    public int? Int3 { get; set; }
}

 public enum Enum2
    {
        x,
        y
    }

因为oracle数据库我们习惯于表名和字段名大写，所以oracle的测试实体类定义如下：

[Table("NULLABLETABLE")]
[Description("NullableTable")]
public class NullableTable
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    [Key]
    [Column("ID")]
    public int Id { get; set; }
    [Description("Int2")]
    [Column("INT2")]
    public int? Int2 { get; set; }
    [Description("Long2")]
    [Column("LONG2")]
    public long? Long2 { get; set; }
    [Column("FLOAT2")]
    public float? Float2 { get; set; }
    [Column("DOUBLE2")]
    public double? Double2 { get; set; }
    [Column("DECIMAL2")]
    public decimal? Decimal2 { get; set; }
    [Column("DECIMAL3")]
    [DecimalPrecision(20,4)]
    public decimal? Decimal3 { get; set; }
    [Column("GUID2")]
    public Guid? Guid2 { get; set; }
    [Column("SHORT2")]
    public short? Short2 { get; set; }
    [Column("DATETIME2")]
    public DateTime? DateTime2 { get; set; }
    [Column("BOOL2")]
    public bool? Bool2 { get; set; }
    [Column("TIMESPAN2")]
    public TimeSpan? TimeSpan2 { get; set; }
    [Column("BYTE2")]
    public byte? Byte2 { get; set; }

    [Column("STRING2")]
    [StringLength(100)]
    public string String2 { get; set; }
    [Column("STRING3")]
    public string String3 { get; set; }
    [Column("ENUM2")]
    public Enum2? Enum2 { get; set; }

    [Column("TESTINT3")]
    [Description("Int2")]
    public int? Int3 { get; set; }
}

实验我们采用的是code first，先利用SummerBoot框架的可用于依赖注入的，数据库表和c#实体类互相转换的接口实现功能从实体类生成相应的数据库表，本次实验批量插入2w条数据来对比时间，定义一个列表，用循环的方式给这个列表添加2w条数据。

var nullableTableList3 = new List<NullableTable>();
var now = DateTime.Now;
for (int i = 0; i < 20000; i++)
{
    var a = new NullableTable()
    {
        Int2 = 2,
        Bool2 = true,
        Byte2 = 1,
        DateTime2 = now,
        Decimal2 = 1m,
        Decimal3 = 1.1m,
        Double2 = 1.1,
        Float2 = (float)1.1,
        Guid2 = Guid.NewGuid(),
        Id = 0,
        Short2 = 1,
        TimeSpan2 = TimeSpan.FromHours(1),
        String2 = "sb",
        String3 = "sb",
        Long2 = 2,
        Enum2 = Model.Enum2.y,
        Int3 = 4
    };
    nullableTableList3.Add(a);
}

数据库驱动上的选择是这样的，sqlserver采用微软官方驱动System.Data.SqlClient，oracle采用官方驱动Oracle.ManagedDataAccess.Core，mysql采用社区驱动MySqlConnector（为啥mysql不采用官方的驱动呢？因为官方的驱动封装的太差了，社区的驱动支持列名映射，同时项目里官方驱动和社区驱动可以共存）。
同时快速批量插入均支持异步同步，这里仅演示同步，异步的实现基本一样。

3.sqlserver快速批量插入

sqlserver官方提供的批量插入方式是SqlBulkCopy，参数为一个dataTable对象，原生的批量插入代码如下,采用StopWatch类进行计时,测试前都会用DELETE from NullableTable 语句清空表，测试里循环跑5次，获取总时间后除以5获取平均值，合计插入10w条数据。

var sw = new Stopwatch();
sw.Start();
for (int i = 0; i < 5; i++)
{
  using (var dbConnection = new SqlConnection(connectionString))
  {
      dbConnection.Open();

      SqlBulkCopy sqlBulkCopy = new SqlBulkCopy(dbConnection, SqlBulkCopyOptions.KeepIdentity,
          null);
      sqlBulkCopy.BatchSize = 20000;
      sqlBulkCopy.DestinationTableName = "NullableTable";
      //针对列名做一下映射
      sqlBulkCopy.ColumnMappings.Add("Int2", "Int2");
      sqlBulkCopy.ColumnMappings.Add("Bool2", "Bool2");
      sqlBulkCopy.ColumnMappings.Add("Byte2", "Byte2");
      sqlBulkCopy.ColumnMappings.Add("DateTime2", "DateTime2");
      sqlBulkCopy.ColumnMappings.Add("Decimal2", "Decimal2");
      sqlBulkCopy.ColumnMappings.Add("Decimal3", "Decimal3");
      sqlBulkCopy.ColumnMappings.Add("Double2", "Double2");
      sqlBulkCopy.ColumnMappings.Add("Float2", "Float2");
      sqlBulkCopy.ColumnMappings.Add("Guid2", "Guid2");
      sqlBulkCopy.ColumnMappings.Add("Short2", "Short2");
      sqlBulkCopy.ColumnMappings.Add("TimeSpan2", "TimeSpan2");

      sqlBulkCopy.ColumnMappings.Add("String2", "String2");
      sqlBulkCopy.ColumnMappings.Add("String3", "String3");
      sqlBulkCopy.ColumnMappings.Add("Long2", "Long2");
      sqlBulkCopy.ColumnMappings.Add("Enum2", "Enum2");
      sqlBulkCopy.ColumnMappings.Add("Int3", "TestInt3");
      //将实体类列表转换成dataTable
      var table = nullableTableList3.ToDataTable();
      sqlBulkCopy.WriteToServer(table);
  }

}
sw.Stop();            
var totalTime= sw.ElapsedMilliseconds;
var avgValue = totalTime / 5;

实验结果如下，sql server中：
采用快速批量插入10w条数据，时间合计1858毫秒，平均插入2w条数据仅需371毫秒。
采用insert into语句，循环插入10w条数据，时间合计457606毫秒，平均插入2w条数据需91521毫秒。

4.实体类列表转dataTable的扩展方法

这里有一个实体类列表转dataTable的扩展方法，采用的是表达式树+构建委托的方式，性能不错，大家可以参考，代码实现如下。

public static ConcurrentDictionary<string, object> CacheDictionary = new ConcurrentDictionary<string, object>();
/// <summary>
/// 构建一个object数据转换成一维数组数据的委托
/// </summary>
/// <param name="objType"></param>
/// <param name="propertyInfos"></param>
/// <returns></returns>
public static Func<T, object[]> BuildObjectGetValuesDelegate<T>(List<PropertyInfo> propertyInfos) where T : class
{
    var objParameter = Expression.Parameter(typeof(T), "model");
    var selectExpressions = propertyInfos.Select(it => BuildObjectGetValueExpression(objParameter, it));
    var arrayExpression = Expression.NewArrayInit(typeof(object), selectExpressions);
    var result = Expression.Lambda<Func<T, object[]>>(arrayExpression, objParameter).Compile();
    return result;
}


/// <summary>
/// 构建对象获取单个值得
/// </summary>
/// <param name="modelExpression"></param>
/// <param name="propertyInfo"></param>
/// <returns></returns>
public static Expression BuildObjectGetValueExpression(ParameterExpression modelExpression, PropertyInfo propertyInfo)
{
    var propertyExpression = Expression.Property(modelExpression, propertyInfo);
    var convertExpression = Expression.Convert(propertyExpression, typeof(object));
    return convertExpression;
}

public static DataTable ToDataTable<T>(this IEnumerable<T> source, List<PropertyInfo> propertyInfos = null,bool useColumnAttribute=false) where T : class
{
    var table = new DataTable("template");
    if (propertyInfos == null || propertyInfos.Count == 0)
    {
        propertyInfos = typeof(T).GetProperties().Where(it => it.CanRead).ToList();
    }
    foreach (var propertyInfo in propertyInfos)
    {
        var columnName=useColumnAttribute?(propertyInfo.GetCustomAttribute<ColumnAttribute>()?.Name?? propertyInfo.Name) : propertyInfo.Name;
        table.Columns.Add(columnName, ChangeType(propertyInfo.PropertyType));
    }

    Func<T, object[]> func;
    var key = typeof(T).FullName + propertyInfos.Select(it => it.Name).ToList().StringJoin();
    if (CacheDictionary.TryGetValue(key, out var cacheFunc))
    {
        func = (Func<T, object[]>)cacheFunc;
    }
    else
    {
        func = BuildObjectGetValuesDelegate<T>(propertyInfos);
        CacheDictionary.TryAdd(key, func);
    }

    foreach (var model in source)
    {
        var rowData = func(model);
        table.Rows.Add(rowData);
    }

    return table;
}

private static Type ChangeType(Type type)
{
    if (type.IsNullable())
    {
        type = Nullable.GetUnderlyingType(type);
    }

    return type;
}

5.oracle快速批量插入

oracle官方提供的批量插入方式是ArrayBindCount，即数组批量插入，原生的批量插入代码如下，计时方式与sqlserver相同

var total = 20000;
var sw = new Stopwatch();
sw.Start();
for (int i = 0; i < 5; i++)
{
    var connection = new OracleConnection(connectionString);
    connection.Open();
    int?[] Int2 = new int?[total];
    bool[] Bool2 = new bool[total];
    byte[] Byte2 = new byte[total];
    DateTime[] DateTime2 = new DateTime[total];
    decimal?[] Decimal2 = new decimal?[total];
    decimal[] Decimal3 = new decimal[total];
    double[] Double2 = new double[total];
    float[] Float2 = new float[total];
    Guid?[] Guid2 = new Guid?[total];
    short[] Short2 = new short[total];
    TimeSpan[] TimeSpan2 = new TimeSpan[total];
    string[] String2 = new string[total];
    string[] String3 = new string[total];
    long[] Long2 = new long[total];
    Enum2[] Enum2 = new Enum2[total];

    for (int j = 0; j < total; j++)
    {
        Int2[j] = 2;
        Bool2[j] = true;
        Byte2[j] = 1;
        DateTime2[j] = now;
        Decimal2[j] = 1m;
        Decimal3[j] = 1.1m;
        Double2[j] = 1.1;
        Float2[j] = (float) 1.1;
        Guid2[j] = Guid.NewGuid();
        Short2[j] = 1;
        TimeSpan2[j] = TimeSpan.FromHours(1);
        String2[j] = "sb";
        String3[j] = "sb";
        Long2[j] = 2;
        Enum2[j] = Model.Enum2.y;
    }

    var c = (int) Model.Enum2.y;
    OracleParameter pInt2 = new OracleParameter();
    pInt2.OracleDbType = OracleDbType.Int32;
    pInt2.Value = Int2;

    OracleParameter pBool2 = new OracleParameter();
    pBool2.OracleDbType = OracleDbType.Byte;
    pBool2.Value = Bool2;

    OracleParameter pByte2 = new OracleParameter();
    pByte2.OracleDbType = OracleDbType.Byte;
    pByte2.Value = Byte2;

    OracleParameter pDateTime2 = new OracleParameter();
    pDateTime2.OracleDbType = OracleDbType.TimeStamp;
    pDateTime2.Value = DateTime2;

    OracleParameter pDecimal2 = new OracleParameter();
    pDecimal2.OracleDbType = OracleDbType.Decimal;
    pDecimal2.Value = Decimal2;

    OracleParameter pDecimal3 = new OracleParameter();
    pDecimal3.OracleDbType = OracleDbType.Decimal;
    pDecimal3.Value = Decimal3;

    OracleParameter pDouble2 = new OracleParameter();
    pDouble2.OracleDbType = OracleDbType.Double;
    pDouble2.Value = Double2;

    OracleParameter pFloat2 = new OracleParameter();
    pFloat2.OracleDbType = OracleDbType.BinaryFloat;
    pFloat2.Value = Float2;


    OracleParameter pGuid2 = new OracleParameter();
    pGuid2.OracleDbType = OracleDbType.Raw;
    pGuid2.Value = Guid2;

    OracleParameter pShort2 = new OracleParameter();
    pShort2.OracleDbType = OracleDbType.Int16;
    pShort2.Value = Short2;

    OracleParameter pTimeSpan2 = new OracleParameter();
    pTimeSpan2.OracleDbType = OracleDbType.IntervalDS;
    pTimeSpan2.Value = TimeSpan2;

    OracleParameter pString2 = new OracleParameter();
    pString2.OracleDbType = OracleDbType.Varchar2;
    pString2.Value = String2;

    OracleParameter pString3 = new OracleParameter();
    pString3.OracleDbType = OracleDbType.Varchar2;
    pString3.Value = String3;


    OracleParameter pLong2 = new OracleParameter();
    pLong2.OracleDbType = OracleDbType.Long;
    pLong2.Value = Long2;

    OracleParameter pEnum2 = new OracleParameter();
    pEnum2.OracleDbType = OracleDbType.Byte;
    pEnum2.Value = Enum2;
    // create command and set properties
    OracleCommand cmd = connection.CreateCommand();
    cmd.CommandText =
        "INSERT INTO NULLABLETABLE (INT2, LONG2, FLOAT2, DOUBLE2, DECIMAL2, DECIMAL3, GUID2, SHORT2, DATETIME2, BOOL2, TIMESPAN2, BYTE2, STRING2, STRING3,ENUM2) VALUES(:1,:2,:3,:4,:5,:6,:7,:8,:9,:10,:11,:12,:13,:14,:15)";
    cmd.ArrayBindCount = total;
    cmd.Parameters.Add(pInt2);
    cmd.Parameters.Add(pLong2);
    cmd.Parameters.Add(pFloat2);
    cmd.Parameters.Add(pDouble2);
    cmd.Parameters.Add(pDecimal2);
    cmd.Parameters.Add(pDecimal3);
    cmd.Parameters.Add(pGuid2);
    cmd.Parameters.Add(pShort2);
    cmd.Parameters.Add(pDateTime2);
    cmd.Parameters.Add(pBool2);
    cmd.Parameters.Add(pTimeSpan2);
    cmd.Parameters.Add(pByte2);
    cmd.Parameters.Add(pString2);
    cmd.Parameters.Add(pString3);
    cmd.Parameters.Add(pEnum2);
    cmd.ExecuteNonQuery();
}
sw.Stop();

var totalTime = sw.ElapsedMilliseconds;
var avgValue = totalTime / 5;

实验结果如下，oracle中：
采用快速批量插入10w条数据，时间合计2323毫秒，平均插入2w条数据仅需464毫秒。
采用insert into语句，循环插入10w条数据，时间合计462837毫秒，平均插入2w条数据仅需92567毫秒。

6.mysql快速批量插入

mysql社区驱动MySqlConnector提供的批量插入方式是SqlBulkCopy，基于mysql自身的文件上传机制进行批量插入，参数为一个dataTable对象，原生的批量插入代码如下,计时方式与sqlserver相同,同时，mysql的连接字符串里要添加";AllowLoadLocalInfile=true"，即连接字符串的形式应该是"Server= ;Database=;User ID=;Password=;AllowLoadLocalInfile=true"，同时在mysql数据库上执行"set global local_infile=1"开启批量上传

var sw = new Stopwatch();
sw.Start();
for (int j = 0; j < 5; j++)
{
    using (var dbConnection = new MySqlConnection(connectionString))
    {
        dbConnection.Open();

        MySqlBulkCopy sqlBulkCopy = new MySqlBulkCopy(dbConnection, null);
        sqlBulkCopy.DestinationTableName = "NullableTable";
        var propertys = typeof(NullableTable).GetProperties()
            .Where(it => it.CanRead && it.GetCustomAttribute<NotMappedAttribute>() == null).ToList();

        for (int i = 0; i < propertys.Count; i++)
        {
            var property = propertys[i];
            var columnName = property.GetCustomAttribute<ColumnAttribute>()?.Name ?? property.Name;

            if (property.PropertyType.GetUnderlyingType() == typeof(Guid))
            {
                sqlBulkCopy.ColumnMappings.Add(new MySqlBulkCopyColumnMapping(i, "@tmp",
                    $"{columnName} =unhex(@tmp)"));
            }
            else
            {
                sqlBulkCopy.ColumnMappings.Add(new MySqlBulkCopyColumnMapping(i, columnName));
            }
        }

        var table = nullableTableList3.ToDataTable();

        SbUtil.ReplaceDataTableColumnType<Guid, byte[]>(table, guid1 => guid1.ToByteArray());
        var c = sqlBulkCopy.WriteToServer(table);
    }
}

sw.Stop();

var totalTime = sw.ElapsedMilliseconds;
var avgValue = totalTime / 5;

实验结果如下，mysql中：
采用快速批量插入10w条数据，时间合计2350毫秒，平均插入2w条数据仅需470毫秒。
采用insert into语句，循环插入10w条数据，时间合计414700毫秒，平均插入2w条数据需82940毫秒。

在mysql中c#的guid对应的mysql字段类型为varbinary(16)，所以table里的guid要转换为字节数组，否则插入数据库后，guid的值就会变成乱码,字节数组传递到mysql服务端后利用unhex函数进行解析，即可正常保存guid类型。 将table里guid的值转为字节数组的方法-SbUtil.ReplaceDataTableColumnType的代码实现如下：

/// <summary>
/// 替换dataTable里的列类型
/// </summary>
/// <param name="dt"></param>
public  static void ReplaceDataTableColumnType<OldType,NewType>(DataTable dt,Func<OldType, NewType> replaceFunc)
{
    var needUpdateColumnIndexList = new List<int>();
    var needUpdateColumnNameList = new List<string>();
    
    for (int i = 0; i < dt.Columns.Count; i++)
    {
        var column = dt.Columns[i];
        if (column.DataType.GetUnderlyingType() == typeof(OldType))
        {
            needUpdateColumnIndexList.Add(i);
            needUpdateColumnNameList.Add(column.ColumnName);
          
        }
    }

    if (needUpdateColumnIndexList.Count == 0)
    {
        return;
    }

    var nameMapping = new Dictionary<string, string>();
    for (int i = 0; i < needUpdateColumnIndexList.Count; i++)
    {
        var oldColumnName = needUpdateColumnNameList[i];
        var newColumnName = Guid.NewGuid().ToString("N");
        nameMapping.Add(newColumnName, oldColumnName);
      
        dt.Columns.Add(newColumnName, typeof(byte[])).SetOrdinal(needUpdateColumnIndexList[i]);
        for (int j = 0; j < dt.Rows.Count; j++)
        {
            var c = (dt.Rows[j][oldColumnName]);
            dt.Rows[j][newColumnName] = replaceFunc((OldType)(dt.Rows[j][oldColumnName]));
        }
        dt.Columns.Remove(oldColumnName);
    }
    
    for (int i = 0; i < dt.Columns.Count; i++)
    {
        var columnName = dt.Columns[i].ColumnName;
        if (nameMapping.ContainsKey(columnName))
        {
            dt.Columns[i].ColumnName = nameMapping[columnName];
        }
    }

}

7.SummerBoot对各数据库快速批量插入的封装

基于以上各种数据库对于快速批量插入的原生写法过于复杂难记，SummerBoot对其进行了封装，在声明式编程的理念下，封装后仅需3步即可快速批量插入，这里以sqlserver举例。

7.1在StartUp.cs中添加summerBoot的服务支持

services.AddSummerBoot();
services.AddSummerBootRepository(it =>
{
    it.DbConnectionType = typeof(SqlConnection);
    it.ConnectionString = connectionString;
});

7.2添加仓储接口

[AutoRepository]
public interface INullableTableRepository : IBaseRepository<NullableTable>
{
    
}

7.3注入仓储接口后直接调用FastBatchInsert方法

var sw = new Stopwatch();
sw.Start();
for (int i = 0; i < 5; i++)
{
    nullableTableRepository.FastBatchInsert(nullableTableList3);
}
sw.Stop();
  
var totalTime= sw.ElapsedMilliseconds;
var avgValue = totalTime / 5;

实验结果如下，sql server中：
采用SummerBoot统一封装后快速批量插入10w条数据，时间合计3926（原生快速批量写法1858）毫秒，平均插入2w条数据仅需785(原生快速批量写法371)毫秒。从对比可以看出，经过SummerBoot封装后，快速批量插入所花费的时间有所增加，但是对于这么大数据量而言，这点多消耗的时间和节省的开发量对比，不值一提。

写在最后

SummerBoot是一款声明式编程框架，专注于”做什么”而不是”如何去做”，更多用法，可参考SummerBoot文档，也可以加入QQ群:799648362反馈建议。同时各位看官，如果你觉得这篇文章还不错的话，请帮忙一键三连哦(推荐+关注+github star)