private byte *SplitPageInHalf(Page rightPage) { bool toRight; var currentIndex = _page.LastSearchPosition; var splitIndex = _page.NumberOfEntries / 2; if (currentIndex <= splitIndex) { toRight = false; } else { toRight = true; var leftPageEntryCount = splitIndex; var rightPageEntryCount = _page.NumberOfEntries - leftPageEntryCount + 1; if (rightPageEntryCount > leftPageEntryCount) { splitIndex++; Debug.Assert(splitIndex < _page.NumberOfEntries); } } PrefixNode[] prefixes = null; if (_tree.KeysPrefixing && _page.HasPrefixes) { prefixes = _page.GetPrefixes(); } if (_page.IsLeaf || prefixes != null) { splitIndex = AdjustSplitPosition(currentIndex, splitIndex, prefixes, ref toRight); } var currentKey = _page.GetNodeKey(splitIndex); MemorySlice seperatorKey; if (toRight && splitIndex == currentIndex) { seperatorKey = currentKey.Compare(_newKey) < 0 ? currentKey : _newKey; } else { seperatorKey = currentKey; } Page parentOfRight; AddSeparatorToParentPage(rightPage.PageNumber, seperatorKey, out parentOfRight); var parentOfPage = _cursor.CurrentPage; MemorySlice instance = _page.CreateNewEmptyKey(); if (prefixes != null) { for (int i = 0; i < prefixes.Length; i++) { var prefix = prefixes[i]; rightPage.WritePrefix(new Slice(prefix.ValuePtr, prefix.PrefixLength), i); } } bool addedAsImplicitRef = false; if (_page.IsBranch && toRight && seperatorKey == _newKey) { // _newKey needs to be inserted as first key (BeforeAllKeys) to the right page, so we need to add it before we move entries from the current page AddNodeToPage(rightPage, 0, _tree.KeysPrefixing ? (MemorySlice)PrefixedSlice.BeforeAllKeys : Slice.BeforeAllKeys); addedAsImplicitRef = true; } // move the actual entries from page to right page ushort nKeys = _page.NumberOfEntries; for (int i = splitIndex; i < nKeys; i++) { NodeHeader *node = _page.GetNode(i); if (_page.IsBranch && rightPage.NumberOfEntries == 0) { rightPage.CopyNodeDataToEndOfPage(node, _tree.KeysPrefixing ? (MemorySlice)PrefixedSlice.BeforeAllKeys : Slice.BeforeAllKeys); } else { _page.SetNodeKey(node, ref instance); var key = rightPage.PrepareKeyToInsert(instance, rightPage.NumberOfEntries); rightPage.CopyNodeDataToEndOfPage(node, key); } } _page.Truncate(_tx, splitIndex); byte *pos; if (addedAsImplicitRef == false) { try { if (toRight && _cursor.CurrentPage.PageNumber != parentOfRight.PageNumber) { // modify the cursor if we are going to insert to the right page _cursor.Pop(); _cursor.Push(parentOfRight); } // actually insert the new key pos = toRight ? InsertNewKey(rightPage) : InsertNewKey(_page); } catch (InvalidOperationException e) { if (e.Message.StartsWith("The page is full and cannot add an entry") == false) { throw; } throw new InvalidOperationException(GatherDetailedDebugInfo(rightPage, currentKey, seperatorKey, currentIndex, splitIndex, toRight), e); } } else { pos = null; _cursor.Push(rightPage); } if (_page.IsBranch) // remove a branch that has only one entry, the page ref needs to be added to the parent of the current page { Debug.Assert(_page.NumberOfEntries > 0); Debug.Assert(rightPage.NumberOfEntries > 0); if (_page.NumberOfEntries == 1) { RemoveBranchWithOneEntry(_page, parentOfPage); } if (rightPage.NumberOfEntries == 1) { RemoveBranchWithOneEntry(rightPage, parentOfRight); } } return(pos); }