/// <summary>
/// Filters a queryable to the data within a specified range partition.
/// </summary>
/// <typeparam name="TData">The type of the data.</typeparam>
/// <typeparam name="TPartition">The type of the partition value.</typeparam>
/// <param name="source">The source queryable.</param>
/// <param name="key">A selector for the partitioned value.</param>
/// <param name="partition">The partition.</param>
public static IQueryable <TData> WithinPartition <TData, TPartition>(
this IQueryable <TData> source,
Expression <Func <TData, TPartition> > key,
IStreamQueryRangePartition <TPartition> partition)
{
var lower = Expression.Constant(partition.LowerBoundExclusive);
var upper = Expression.Constant(partition.UpperBoundInclusive);
var compareTo = MethodInfoFor <TPartition> .CompareTo;
var selectLeft = Expression.GreaterThan(
Expression.Call(key.Body,
compareTo,
lower), Expression.Constant(0));
var selectRight = Expression.LessThanOrEqual(
Expression.Call(key.Body,
compareTo,
upper), Expression.Constant(0));
var filterExpression = Expression.AndAlso(selectLeft, selectRight);
return(source.Where(
Expression.Lambda <Func <TData, bool> >(filterExpression, key.Parameters.Single())));
}
/// <summary>
/// Splits a query partition into several smaller, non-overlapping, gapless partitions.
/// </summary>
public static IEnumerable <IStreamQueryRangePartition <TPartition> > Among <TPartition>(
this IStreamQueryRangePartition <TPartition> partition,
int numberOfPartitions)
{
if (typeof(TPartition) == typeof(Guid))
{
dynamic partitions = SqlGuidPartitionBuilder.ByRange(
(dynamic)partition.LowerBoundExclusive,
(dynamic)partition.UpperBoundInclusive,
numberOfPartitions);
return(partitions);
}
if (typeof(TPartition) == typeof(int))
{
dynamic partitions = Int32PartitionBuilder.ByRange(
(dynamic)partition.LowerBoundExclusive,
(dynamic)partition.UpperBoundInclusive,
numberOfPartitions);
return(partitions);
}
if (typeof(TPartition) == typeof(long))
{
dynamic partitions = Int64PartitionBuilder.ByRange(
(dynamic)partition.LowerBoundExclusive,
(dynamic)partition.UpperBoundInclusive,
numberOfPartitions);
return(partitions);
}
if (typeof(TPartition) == typeof(BigInteger))
{
dynamic partitions = BigIntegerPartitionBuilder.ByRange(
(dynamic)partition.LowerBoundExclusive,
(dynamic)partition.UpperBoundInclusive,
numberOfPartitions);
return(partitions);
}
throw new ArgumentException(string.Format("Partitions of type {0} cannot be generated dynamically.", typeof(TPartition)));
}
