public BTreeOnHeapLeaf <T> GetLeaf(HeapID leafHeapID, BTreeOnHeapIndexRecord leafIndexRecord)
{
BTreeOnHeapLeaf <T> result;
if (!m_leavesCache.ContainsKey(leafHeapID.Value))
{
BTreeOnHeapLeaf <T> leaf = GetLeafFromHeap(leafHeapID);
if (leaf != null)
{
m_leavesCache.Add(leafHeapID.Value, leaf);
}
result = leaf;
}
else
{
result = m_leavesCache[leafHeapID.Value];
}
if (result != null && leafIndexRecord != null)
{
// The BTH index node might have changed since the leaf was stored,
// We must not use the index node stored in the cache.
result.Index = leafIndexRecord.Index;
}
return(result);
}
public BTreeOnHeapLeaf <T> GetLeafFromHeap(HeapID leafHeapID)
{
// The hid is set to zero if the BTH is empty
if (leafHeapID.Value == 0)
{
return(null);
}
else
{
byte[] leafBytes = GetHeapItem(leafHeapID);
BTreeOnHeapLeaf <T> result = new BTreeOnHeapLeaf <T>(leafBytes);
result.HeapID = leafHeapID;
return(result);
}
}
public BTreeOnHeapLeaf <T> Split()
{
int newNodeStartIndex = Records.Count / 2;
BTreeOnHeapLeaf <T> newNode = new BTreeOnHeapLeaf <T>();
newNode.Index = Index;
// Heap ID will be given when the item will be added
for (int index = newNodeStartIndex; index < Records.Count; index++)
{
newNode.Records.Add(Records[index]);
}
Records.RemoveRange(newNodeStartIndex, Records.Count - newNodeStartIndex);
return(newNode);
}
// the PC is simply a BTH with cbKey set to 2 and cbEnt set to 6
public T FindRecord(byte[] key)
{
BTreeOnHeapLeaf <T> leaf = FindLeaf(key);
if (leaf != null)
{
foreach (T record in leaf.Records)
{
// All the entries in the child have key values greater than or equal to this key value.
if (record.IsKeyEquals(key))
{
return(record);
}
}
}
return(default(T));
}
public void RemoveRecord(byte[] key)
{
BTreeOnHeapLeaf <T> leaf = FindLeaf(key);
if (leaf != null)
{
int index = leaf.RemoveRecord(key);
if (leaf.Records.Count == 0)
{
RemoveItemFromHeap(leaf.HeapID);
// leaf with 0 entries is invalid and must be deleted
if (leaf.Index == null)
{
// this is the root node
BTreeHeader.hidRoot = HeapID.EmptyHeapID;
BTreeHeader.bIdxLevels = 0;
UpdateBTreeHeader();
}
else
{
DeleteFromIndexRecord(leaf.Index, leaf.HeapID);
}
}
else
{
// will always replace in place (the new leaf is smaller than the old one)
ReplaceHeapItem(leaf.HeapID, leaf.GetBytes());
m_leavesCache[leaf.HeapID.Value] = leaf;
// scanpst.exe report an error if page key does not match the first entry,
// so we want to update the parent
if (index == 0 && leaf.Index != null)
{
UpdateIndexRecord(leaf.Index, leaf.HeapID, leaf.HeapID, leaf.NodeKey);
}
}
}
}
public void AddRecord(T record)
{
BTreeOnHeapLeaf <T> leaf = FindLeaf(record.Key);
if (leaf == null) // BTH is empty
{
leaf = new BTreeOnHeapLeaf <T>();
leaf.InsertSorted(record);
HeapID rootHeapID = AddItemToHeap(leaf.GetBytes());
UpdateRootHeapID(rootHeapID);
}
else if (leaf.Records.Count < leaf.MaximumNumberOfRecords)
{
int insertIndex = leaf.InsertSorted(record);
HeapID existingHeapID = leaf.HeapID;
leaf.HeapID = ReplaceHeapItem(leaf.HeapID, leaf.GetBytes());
m_leavesCache[leaf.HeapID.Value] = leaf;
if (leaf.HeapID.Value != existingHeapID.Value)
{
if (leaf.Index == null)
{
// this is the root node
UpdateRootHeapID(leaf.HeapID);
}
else
{
// update the parent
UpdateIndexRecord(leaf.Index, existingHeapID, leaf.HeapID, leaf.NodeKey);
}
m_leavesCache.Remove(existingHeapID.Value);
}
else if (insertIndex == 0 && leaf.Index != null)
{
// Node key has been modified, we must update the parent
UpdateIndexRecord(leaf.Index, leaf.HeapID, leaf.HeapID, leaf.NodeKey);
}
}
else
{
// The node is full, we have to split it
BTreeOnHeapLeaf <T> newNode = leaf.Split();
if (record.CompareTo(newNode.NodeKey) > 0)
{
newNode.InsertSorted(record);
}
else
{
int insertIndex = leaf.InsertSorted(record);
if (insertIndex == 0 && leaf.Index != null)
{
// Node key has been modified, we must update the parent
UpdateIndexRecord(leaf.Index, leaf.HeapID, leaf.HeapID, leaf.NodeKey);
}
}
if (leaf.Index == null)
{
// this is a root page and it's full, we have to create a new root
leaf.Index = CreateNewRoot(leaf.NodeKey);
}
// Item will be replaced in place, because it has less items than before
ReplaceHeapItem(leaf.HeapID, leaf.GetBytes());
m_leavesCache[leaf.HeapID.Value] = leaf;
HeapID newNodeHeapID = AddItemToHeap(newNode.GetBytes());
// We made sure we have a parent to add our new page to
InsertIndexRecord(leaf.Index, newNode.NodeKey, newNodeHeapID);
}
}
