Merging Existing DSC Files

After a DSC file set has been sealed, it is not possible to add more files. If you want to create a file set containing the files from two or more existing file sets, you will need to create a completely new file set.

There are three approaches to this, depending on your scenario. The first option is to use the DSC APIs.

string fileSetA = ...;
string fileSetB = ...;
string fileSetAandB = ...;

DscService dsc = new DscService(SampleConfiguration.HeadNode);
DscFileSet result = dsc.CreateFileSet(fileSetAandB, DscCompressionScheme.None);
foreach (var file in dsc.GetFileSet(fileSetA).GetFiles())
    result.AddExistingFile(file);
foreach (var file in dsc.GetFileSet(fileSetB).GetFiles())
    result.AddExistingFile(file);
result.Seal();

The second option is to use a query containing a Concat operator to do this.

context.FromDsc<LineRecord>(fileSetA)
    .Concat(context.FromDsc<LineRecord>(fileSetB))
    .ToDsc(fileSetAandB)
    .SubmitAndWait();

In most cases the Concat operator is the simplest query to use. However there is a third option, to do this within a query using the Union operator.

context.FromDsc<LineRecord>(fileSetA)
    .Union(context.FromDsc<LineRecord>(fileSetB),
            new FalseComparer()).ToDsc(fileSetAandB)
    .SubmitAndWait();

In this case, FalseComparer always returns a false comparison so that the union operation does not remove identical records.

[Serializable]
public class FalseComparer : IEqualityComparer<LineRecord>
{
    public bool Equals(LineRecord x, LineRecord y)
    {
        return false;
    }

    public int GetHashCode(LineRecord obj)
    {
        return obj.GetHashCode();
    }
}