PCursor = Parent Cursor CCursor = Child Cursor SQL text(statement) is stored as parent - child cursor combination. They have one to many relationship. PCursor : CCursor = 1 : M For instance, let's assume that ... User A submits "select * from tab_a". User B submits "select * from tab_a". Same sql text, but different sql cursor. In this case, we have one parent cursor whose sql text is "select * from tab_a", and 2 child cursors whose execution plans are different. The area that execution plan is stored is called "sql area". Hope this clarifies the terms.