https://github.com/dario-l/linearkeyallocator

Linear key allocator for MS Sql Server
https://github.com/dario-l/linearkeyallocator

chunk database generator hilo identifier key-allocator linear rdbms

Last synced: 11 days ago
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Linear key allocator for MS Sql Server

• Host: GitHub
• URL: https://github.com/dario-l/linearkeyallocator
• Owner: dario-l
• License: mit
• Created: 2019-12-04T15:16:22.000Z (about 5 years ago)
• Default Branch: master
• Last Pushed: 2024-01-17T08:41:09.000Z (12 months ago)
• Last Synced: 2024-11-05T19:12:39.267Z (about 2 months ago)
• Topics: chunk, database, generator, hilo, identifier, key-allocator, linear, rdbms
• Language: C#
• Homepage:
• Size: 27.3 KB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# LinearKeyAllocator

![LinearKeyAllocator](https://img.shields.io/nuget/v/LinearKeyAllocator)

LinearKeyAllocator allows to generate incremental keys (int, long) based

on last seed value stored in database.

Works likes the HiLo algorithm (from NHibernate) but better becouse

do not create big holes when application restarts.

It aims to be a tool for generating database keys without having to

rely on RDBMS identity column.

LinearKeyAllocator works like database 'Sequence'.

It means does not attach to any ambient transaction.

Once generated chunk of keys are available until application restarts.

After restart it will start from last saved max value.

**Why is it better than HiLo?**

Set LinearKeyAllocator seedSize to 20.

```

LinearKeyAllocator          HiLo

...

100                         65536

101                         65537

102                         65538

... application restart

120                         131072

121                         131073

122                         131073

... application restart

140                         196608

```

**Example**

``` c#

class Program

{

    private static string cnn =

        "Server=(local); Database=Test; Trusted_Connection=True; MultipleActiveResultSets=true";

    static async Task Main(string[] args)

    {

        var generator = await new KeyAllocator(cnn).Initialize();

        const string type1 = "Type1";

        const string type2 = "Type2";

        using var scope =

            new TransactionScope(

                TransactionScopeOption.Required,

                TransactionScopeAsyncFlowOption.Enabled);

        for (var i = 0; i < 5000; i++)

        {

            var key = (i % 2 == 0) ? type1 : type2;

            var value = await generator.GenerateInt32(key);

            Console.WriteLine("{0}: {1}", key, value);

        }

        scope.Complete();

        Console.WriteLine("Press any key...");

        Console.ReadKey();

    }

}

```

**Sql Script**

``` SQL

CREATE TABLE [dbo].[LinearKeyAllocator](

    [Key] [varchar](255) NOT NULL,

    [NextMax] [bigint] NOT NULL,

    CONSTRAINT [PK_LinearKeyAllocator] PRIMARY KEY CLUSTERED ([Key] ASC)

) ON [PRIMARY]

```