In Oracle's object-relational storage framework, the null indicator is kept in a bitmap, and each embedded attribute takes up 1 bit. This implies that: For a maximum of 8 attributes -> the null indicator column length remains as 1 byte. For 8+ attributes -> Oracle byte-maps on a scale that encompasses all attributes. For instance: 9–16 attributes: 2 bytes 17–24 attributes: 3 bytes and so forth. Simply put, the null indicator column length is essentially CEIL(n / 8) bytes, where n is the embedded attributes. Hence, if your object has more than 8 attributes, the null indicator length grows beyond 1 byte.