public byte *Execute()
{
Page rightPage = _tree.NewPage(_page.Flags, 1);
if (_cursor.PageCount == 0) // we need to do a root split
{
Page newRootPage = _tree.NewPage(_tree.KeysPrefixing ? PageFlags.Branch | PageFlags.KeysPrefixed : PageFlags.Branch, 1);
_cursor.Push(newRootPage);
_treeState.RootPageNumber = newRootPage.PageNumber;
_treeState.Depth++;
// now add implicit left page
newRootPage.AddPageRefNode(0, _tree.KeysPrefixing ? (MemorySlice)PrefixedSlice.BeforeAllKeys : Slice.BeforeAllKeys, _page.PageNumber);
_parentPage = newRootPage;
_parentPage.LastSearchPosition++;
}
else
{
// we already popped the page, so the current one on the stack is the parent of the page
if (_tree.Name == Constants.FreeSpaceTreeName)
{
// a special case for FreeSpaceTree because the allocation of a new page called above
// can cause a delete of a free space section resulting in a run of the tree rebalancer
// and here the parent page that exists in cursor can be outdated
_parentPage = _tx.ModifyPage(_cursor.CurrentPage.PageNumber, _tree, null); // pass _null_ to make sure we'll get the most updated parent page
_parentPage.LastSearchPosition = _cursor.CurrentPage.LastSearchPosition;
_parentPage.LastMatch = _cursor.CurrentPage.LastMatch;
}
else
{
_parentPage = _tx.ModifyPage(_cursor.CurrentPage.PageNumber, _tree, _cursor.CurrentPage);
}
_cursor.Update(_cursor.Pages.First, _parentPage);
}
if (_page.IsLeaf)
{
_tree.ClearRecentFoundPages();
}
if (_tree.Name == Constants.FreeSpaceTreeName)
{
// we need to refresh the LastSearchPosition of the split page which is used by the free space handling
// because the allocation of a new page called above could remove some sections
// from the page that is being split
_page.NodePositionFor(_newKey);
}
if (_page.LastSearchPosition >= _page.NumberOfEntries)
{
// when we get a split at the end of the page, we take that as a hint that the user is doing
// sequential inserts, at that point, we are going to keep the current page as is and create a new
// page, this will allow us to do minimal amount of work to get the best density
Page branchOfSeparator;
byte *pos;
if (_page.IsBranch)
{
if (_page.NumberOfEntries > 2)
{
// here we steal the last entry from the current page so we maintain the implicit null left entry
NodeHeader *node = _page.GetNode(_page.NumberOfEntries - 1);
Debug.Assert(node->Flags == NodeFlags.PageRef);
rightPage.AddPageRefNode(0, _tree.KeysPrefixing ? (MemorySlice)PrefixedSlice.BeforeAllKeys : Slice.BeforeAllKeys, node->PageNumber);
pos = AddNodeToPage(rightPage, 1);
var separatorKey = _page.GetNodeKey(node);
AddSeparatorToParentPage(rightPage.PageNumber, separatorKey, out branchOfSeparator);
_page.RemoveNode(_page.NumberOfEntries - 1);
}
else
{
_tree.FreePage(rightPage); // return the unnecessary right page
pos = AddSeparatorToParentPage(_pageNumber, _newKey, out branchOfSeparator);
if (_cursor.CurrentPage.PageNumber != branchOfSeparator.PageNumber)
{
_cursor.Push(branchOfSeparator);
}
return(pos);
}
}
else
{
AddSeparatorToParentPage(rightPage.PageNumber, _newKey, out branchOfSeparator);
pos = AddNodeToPage(rightPage, 0);
}
_cursor.Push(rightPage);
return(pos);
}
return(SplitPageInHalf(rightPage));
}
public Page Execute(Page page)
{
_tree.ClearRecentFoundPages();
if (_cursor.PageCount <= 1) // the root page
{
RebalanceRoot(page);
return(null);
}
var parentPage = _tx.ModifyPage(_cursor.ParentPage.PageNumber, _tree, _cursor.ParentPage);
_cursor.Update(_cursor.Pages.First.Next, parentPage);
if (page.NumberOfEntries == 0) // empty page, just delete it and fixup parent
{
// need to change the implicit left page
if (parentPage.LastSearchPosition == 0 && parentPage.NumberOfEntries > 2)
{
var newImplicit = parentPage.GetNode(1)->PageNumber;
parentPage.RemoveNode(0);
parentPage.ChangeImplicitRefPageNode(newImplicit);
}
else // will be set to rights by the next rebalance call
{
parentPage.RemoveNode(parentPage.LastSearchPositionOrLastEntry);
}
_tree.FreePage(page);
_cursor.Pop();
return(parentPage);
}
if (page.IsBranch && page.NumberOfEntries == 1)
{
RemoveBranchWithOneEntry(page, parentPage);
_cursor.Pop();
return(parentPage);
}
var minKeys = page.IsBranch ? 2 : 1;
if ((page.UseMoreSizeThan(_tx.DataPager.PageMinSpace)) &&
page.NumberOfEntries >= minKeys)
{
return(null); // above space/keys thresholds
}
Debug.Assert(parentPage.NumberOfEntries >= 2); // if we have less than 2 entries in the parent, the tree is invalid
var sibling = SetupMoveOrMerge(page, parentPage);
Debug.Assert(sibling.PageNumber != page.PageNumber);
if (page.Flags != sibling.Flags)
{
return(null);
}
minKeys = sibling.IsBranch ? 2 : 1; // branch must have at least 2 keys
if (sibling.UseMoreSizeThan(_tx.DataPager.PageMinSpace) &&
sibling.NumberOfEntries > minKeys)
{
_cursor.Pop();
// neighbor is over the min size and has enough key, can move just one key to the current page
if (page.IsBranch)
{
MoveBranchNode(parentPage, sibling, page);
}
else
{
MoveLeafNode(parentPage, sibling, page);
}
return(parentPage);
}
if (page.LastSearchPosition == 0) // this is the right page, merge left
{
if (TryMergePages(parentPage, sibling, page) == false)
{
return(null);
}
}
else // this is the left page, merge right
{
if (TryMergePages(parentPage, page, sibling) == false)
{
return(null);
}
}
_cursor.Pop();
return(parentPage);
}
public byte *Execute()
{
using (_tree.IsFreeSpaceTree ? _tx.Environment.FreeSpaceHandling.Disable() : null)
{
Page rightPage = _tree.NewPage(_page.Flags, 1);
if (_cursor.PageCount == 0) // we need to do a root split
{
Page newRootPage = _tree.NewPage(_tree.KeysPrefixing ? PageFlags.Branch | PageFlags.KeysPrefixed : PageFlags.Branch, 1);
_cursor.Push(newRootPage);
_tree.State.RootPageNumber = newRootPage.PageNumber;
_tree.State.Depth++;
// now add implicit left page
newRootPage.AddPageRefNode(0, _tree.KeysPrefixing ? (MemorySlice)PrefixedSlice.BeforeAllKeys : Slice.BeforeAllKeys, _page.PageNumber);
_parentPage = newRootPage;
_parentPage.LastSearchPosition++;
}
else
{
// we already popped the page, so the current one on the stack is the parent of the page
_parentPage = _tx.ModifyPage(_cursor.CurrentPage.PageNumber, _tree, _cursor.CurrentPage);
_cursor.Update(_cursor.Pages.First, _parentPage);
}
if (_page.IsLeaf)
{
_tree.ClearRecentFoundPages();
}
if (_page.LastSearchPosition >= _page.NumberOfEntries)
{
// when we get a split at the end of the page, we take that as a hint that the user is doing
// sequential inserts, at that point, we are going to keep the current page as is and create a new
// page, this will allow us to do minimal amount of work to get the best density
Page branchOfSeparator;
byte *pos;
if (_page.IsBranch)
{
if (_page.NumberOfEntries > 2)
{
// here we steal the last entry from the current page so we maintain the implicit null left entry
NodeHeader *node = _page.GetNode(_page.NumberOfEntries - 1);
Debug.Assert(node->Flags == NodeFlags.PageRef);
rightPage.AddPageRefNode(0, _tree.KeysPrefixing ? (MemorySlice)PrefixedSlice.BeforeAllKeys : Slice.BeforeAllKeys, node->PageNumber);
pos = AddNodeToPage(rightPage, 1);
var separatorKey = _page.GetNodeKey(node);
AddSeparatorToParentPage(rightPage.PageNumber, separatorKey, out branchOfSeparator);
_page.RemoveNode(_page.NumberOfEntries - 1);
}
else
{
_tree.FreePage(rightPage); // return the unnecessary right page
pos = AddSeparatorToParentPage(_pageNumber, _newKey, out branchOfSeparator);
if (_cursor.CurrentPage.PageNumber != branchOfSeparator.PageNumber)
{
_cursor.Push(branchOfSeparator);
}
return(pos);
}
}
else
{
AddSeparatorToParentPage(rightPage.PageNumber, _newKey, out branchOfSeparator);
pos = AddNodeToPage(rightPage, 0);
}
_cursor.Push(rightPage);
return(pos);
}
return(SplitPageInHalf(rightPage));
}
}
