Getting started

To set up Koralium in a .Net Core project, the project must be running netcoreapp3.1.

Installation - Apache Arrow Flight

To install Koralium, download the nuget package “Koralium”.

To add support for Apache Arrow Flight, download also:

• Koralium.Transport.ArrowFlight

In your startup.cs file, add the following in ConfigureServices.

public void ConfigureServices(IServiceCollection services)
{
  services.AddGrpc()
    .AddKoraliumFlightServer();
...
  services.AddKoralium(opt =>
  {

  });
...
}

Again in startup.cs, but in the Configure method:

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
...
  app.UseEndpoints(endpoints =>
  {
      ...
      endpoints.MapKoraliumArrowFlight();
      ...
  });
...
}

This will set up the required services and endpoints required to use Koralium with Apache Arrow Flight, which is the recomended endpoint.

Installation - http/json

If you also want to support queries over normal http and return json that is possible.

Install the following nuget packages:

• Koralium

• Koralium.Transport.Json

In startup.cs, in the ConfigureServices method:

public void ConfigureServices(IServiceCollection services)
{
...
  services.AddKoralium(opt =>
  {

  });
...
}

In Configure add the following in UseEndpoints:

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
...
  app.UseEndpoints(endpoints =>
  {
      ...
      endpoints.MapKoraliumJsonPost("sql"); //Map post
      endpoints.MapKoraliumJsonGet("sql"); //Map get
      ...
  });
...
}

This should then allow the following GET call:

http(s)://{your-dns}/sql?query={query}

Adding a table resolver

At this stage we can send in queries, for instance “select * from test”, but we will get an error that the table test does not exist. To fix this we need to add a TableResolver, that allows an implementation on where the data for a table is collected from.

Before we create the resolver though, we need a model class that contains the properties that the table should have.

Example:

public class Test
{
  public long Id { get; set; }

  public string Name { get; set; }
}

After that, we create a class called TestTableResolver as an example if our table will be called Test.

public class TestTableResolver : TableResolver<Test>
{
     protected override Task<IQueryable<Test>> GetQueryableData()
      {
          return Task.FromResult(new List<Test>()
            {
                  new Test()
                {
                    Id = 1,
                    Name = "test"
                }
            }.AsQueryable());
      }
}

Finally, we need add the following in startup.cs, to register the resolver:

public void ConfigureServices(IServiceCollection services)
{
...
  services.AddKoralium(opt =>
  {
    ...
    opt.AddTableResolver<TestTableResolver, Test>(opt =>
    {
        opt.TableName = "test";
    });
    ...
  });
...
}

The table resolver is now registered and one can do the following query:

select * from test