public virtual DistinctResult Merge(DistinctResult[] partitionResults)
{
if (partitionResults == null)
{
throw new ArgumentNullException("partitionResults");
}
if (partitionResults.Length == 0)
{
throw new ArgumentException("Length==0 not supported", "partitionResults");
}
if (!partitionResults[0].Details.Succeeded)
{
return(partitionResults[0]);
}
DistinctResult mergedResult = new DistinctResult(this);
mergedResult.ColumnType = partitionResults[0].ColumnType;
mergedResult.AllValuesReturned = true;
// Construct a helper object of the correct type to natively work with the column
GetUniqueValuesWorker helper = NativeContainer.CreateTypedInstance <GetUniqueValuesWorker>(typeof(GetUniqueValuesWorker <>), partitionResults[0].ColumnType);
IUniqueValueMerger merger = helper.GetMerger();
for (int i = 0; i < partitionResults.Length; ++i)
{
DistinctResult result = partitionResults[i];
// Merge Details
mergedResult.Details.Merge(result.Details);
// Merge whether values remain in any partition
mergedResult.AllValuesReturned &= result.AllValuesReturned;
// Add the values themselves to merge
if (result.Values != null)
{
merger.Add(result.Values.GetColumn(0));
}
}
Array uniqueValues = merger.GetUniqueValues((int)this.Count);
// Copy the merged values into a block
DataBlock mergedBlock = new DataBlock(new string[] { this.Column }, uniqueValues.GetLength(0));
mergedBlock.SetColumn(0, uniqueValues);
mergedResult.Values = mergedBlock;
// If the merge didn't return everything, we didn't return everything
mergedResult.AllValuesReturned &= (uniqueValues.GetLength(0) == merger.Count);
return(mergedResult);
}
public virtual DistinctResult Compute(Partition p)
{
if (p == null)
{
throw new ArgumentNullException("p");
}
ushort countToReturnPerPartition = (this.Count == 0 || this.Count > ushort.MaxValue) ? ushort.MaxValue : (ushort)this.Count;
DistinctResult result = new DistinctResult(this);
// Verify the column exists
if (!p.ContainsColumn(this.Column))
{
result.Details.AddError(ExecutionDetails.ColumnDoesNotExist, this.Column);
return(result);
}
// Find the set of items matching the where clause
ShortSet whereSet = new ShortSet(p.Count);
this.Where.TryEvaluate(p, whereSet, result.Details);
if (result.Details.Succeeded)
{
IUntypedColumn column = p.Columns[this.Column];
// Construct a helper object of the correct type to natively work with the column
GetUniqueValuesWorker helper = NativeContainer.CreateTypedInstance <GetUniqueValuesWorker>(typeof(GetUniqueValuesWorker <>), column.ColumnType);
bool allValuesReturned;
Array uniqueValues = helper.GetUniqueValuesFromColumn(column.InnerColumn, whereSet, countToReturnPerPartition, out allValuesReturned);
result.ColumnType = column.ColumnType;
result.AllValuesReturned = allValuesReturned;
// Build a DataBlock with the results and return it
DataBlock resultValues = new DataBlock(new string[] { this.Column }, uniqueValues.GetLength(0));
resultValues.SetColumn(0, uniqueValues);
result.Values = resultValues;
}
return(result);
}
