Closure Tables (SQL)

A closure table stores all transitive relationships in an outline.

• For example nodes may be allowed a single 'parent', but those node can have their own 'parent.'
• Unravelling this relationship requires recursively retrieving elements and picking through their parent or children relationships.
• A closure table stores secondary references to these; such as relating a node to its grandparent
• Closures might also include a 'depth' to make it possible to request only one or two layers of a conversation
• Thus you can query 'all descendents of this node' when pulling a conversation thread or an outline

• Red-gate