// final AbstractNodePage middlePage = (AbstractNodePage)
// btreePlusElementMgr.getPage(middlePagePosition, null,-1);
// final DataRecordIdentifier middleKey=middlePage.getLastKey();
final DataRecordIdentifier middleKey = parentNonterminal
.getKey(leftPageInParentIndex);
result = leftPage.tryBalanceOrMerge(middleKey, nonTerminalPage);
if (result == 0) {
// page merged in left page
btreePlusElementMgr.freePage(nonTerminalPage
.getPageRecord());
parentNonterminal.remove(inParentIndex);