Extents,”Extents are like the growth rings of a tree. Whenever a segment grows, it gains a new extent. When you first create a table to store items, it gets its first extent. As you insert data into that table, that extent fills up. When the extent fills up, it grabs another extent from the tablespace. When you first create a tablespace, it’s all free space. When you start creating objects

Extents,”Extents are like the growth rings of a tree. Whenever a segment grows, it gains a new extent. When you first create a table to store items, it gets its first extent. As you insert data into that table, that extent fills up. When the extent fills up, it grabs another extent from the tablespace. When you first create a tablespace, it’s all free space. When you start creating objects

that free space gets assigned to segments in the form of extents. Your average tablespace is made up of used extents and free space.”