/// <summary>
/// Creates the temporary file storing the input set, and sorts this file using the given
/// sorting order.
/// </summary>
private void CreateTmpFile()
{
var memSize = 256 * 1024;
using (var bw = new BinaryWriter(File.Open(m_tmpFile, FileMode.Create, FileAccess.Write, FileShare.None))) {
if (m_input.HasNext)
{
var pk = m_input.Peek();
var pkSize = (uint)pk.Count * Database.MEMORY_SIZE_BINDING;
var m = m_planOperator.MemorySize / pkSize;
if (m > Int32.MaxValue)
{
memSize = Int32.MaxValue;
}
else
{
memSize = Convert.ToInt32(m);
}
}
//
// the first step involves simply consuming the input stream in full, and writing
// it to the temporary file. note that it might be better in the future to first
// attempt to fit the input stream in memory.
while (m_input.HasNext)
{
var next = m_input.Next();
for (int i = 0; i < m_sortOrder.Length; i++)
{
var b = next[m_sortOrder[i]];
bw.Write(b.Value.InternalValue);
}
}
}
//
// collect the sort order
var order = new int[m_sortOrder.Length];
for (int i = 0; i < order.Length; i++)
{
order[i] = i;
}
//
// call the external sorting algorithm to sort the file for us
GC.Collect();
ExternalSort.SortFile(m_tmpFile, m_sortOrder.Length, memSize, order);
GC.Collect();
//
// expose a binary reader on the sorted file. we are now ready to start returning
// triples.
m_reader = new BinaryReader(File.Open(m_tmpFile, FileMode.Open, FileAccess.Read, FileShare.Read));
m_tmpFileCreated = true;
}
/// <summary>
/// Builds the indexes over the database. It is assumed that insertion of triples has
/// finished.
/// </summary>
public void BuildIndex()
{
if (m_state == State.Open)
{
if (!m_isBatchInserting)
{
GC.Collect();
ExternalSort.SortBucket(m_sBucket, MAX_TRIPLES_IN_MEMORY);
GC.Collect();
ExternalSort.SortBucket(m_pBucket, MAX_TRIPLES_IN_MEMORY);
GC.Collect();
ExternalSort.SortBucket(m_oBucket, MAX_TRIPLES_IN_MEMORY);
GC.Collect();
m_index.Build();
GC.Collect();
MinifyBuckets();
GC.Collect();
ComputeStatistics();
GC.Collect();
}
}
else
{
throw new InvalidOperationException("Database is not in open state!");
}
}
public static void TestMergeKSortedList()
{
int[] sortedList1 = { 1, 4, 8, 12, 20 };
int[] sortedList2 = { -1, 0, 1, 2 };
int[] sortedList3 = { -5, -4, -3, -2 };
int[] sortedList4 = { 0, 0, 0, 10, 21 };
var result = ExternalSort.MergeKSortedList(new List <int[]>
{
sortedList1,
sortedList2,
sortedList3,
sortedList4
});
}
