Maximum data in an entry

10275 is the maximum size of an entry, but entries have a fixed header of 35 bytes which effectively leaves 10240 bytes maximum for the user data. The user data includes both the external ids and the content of the entry and there is an extra cost of 2 bytes per external id. Which gives the following formula to compute the size of the user data in an entry: content.size + Sum(external_ids.size) + 2 * count(external_ids)