Key hKey = getKey(session, storeData);
constructHKey(session, oldRowDef, oldRow, hKey);
boolean existed = fetch(session, storeData);
if(!existed) {
throw new NoSuchRowException(hKey);
}
RowData currentRow = new RowData();
expandRowData(session, storeData, currentRow);
RowData mergedRow = mergeRows(oldRowDef, currentRow, newRowDef, newRow, selector);