================================================================================
= Graph Elements                                                               =
================================================================================


|--------------------------------------|
| Nodes                                |
|--------------------------------------|
| integer           | ID               |
|--------------------------------------|
| sequence NodeID                      |
|--------------------------------------|


|--------------------------------------|
| Links                                |
|--------------------------------------|
| integer           | ID               |
| integer           | Source           | <- Nodes::ID
| integer           | Target           | <- Nodes::ID
|--------------------------------------|
| sequence LinkID                      |
|--------------------------------------|


================================================================================
= Properties                                                                   =
================================================================================


|--------------------------------------|
| PropertyDataTypes                    |
|--------------------------------------|
| integer           | ID               |
| varchar(255)      | Name             |
|--------------------------------------|
| sequence PropertyDataTypeID          |
|--------------------------------------|


|--------------------------------------|
| PropertyNamespaces                   |
|--------------------------------------|
| integer           | ID               |
| varchar(255)      | Name             |
| integer           | Parent           |
|--------------------------------------|
| sequence PropertyNamespaceID         |
|--------------------------------------|


|--------------------------------------|
| NodeProperties                       |
|--------------------------------------|
| integer           | ID               |
| integer           | DataType         | <- PropertyDataTypes::ID
| varchar(255)      | Name             |
| integer           | Namespace        | <- PropertyNamespaces::ID 
|--------------------------------------|
| sequence NodePropertyID              |
|--------------------------------------|
 \
  \
   |--------------------------------------|
   | NodeIntegerProperties                |
   |--------------------------------------|
   | integer           | Node             | <- Nodes::ID
   | integer           | Property         | <- NodeProperties::ID
   | integer           | Value            |
   |--------------------------------------|

   |--------------------------------------|
   | NodeStringProperties                 |
   |--------------------------------------|
   | integer           | Node             | <- Nodes::ID
   | integer           | Property         | <- NodeProperties::ID
   | varchar(255)      | Value            |
   |--------------------------------------|

   |--------------------------------------|
   | NodeByteArrayProperties              |
   |--------------------------------------|
   | integer           | Node             | <- Nodes::ID
   | integer           | Property         | <- NodeProperties::ID
   | bytea             | Value            |
   |--------------------------------------|

   [ other types as appropriate ]


|--------------------------------------|
| PropertyDataTypes                    |
|--------------------------------------|
| serial            | ID               |
| varchar(255)      | Name             |
|--------------------------------------|


|--------------------------------------|
| LinkProperties                       |
|--------------------------------------|
| integer           | ID               |
| integer           | DataType         | <- PropertyDataTypes::ID
| varchar(255)      | Name             |
| integer           | Namespace        | <- PropertyNamespaces::ID
|--------------------------------------|
| sequence LinkPropertyID              |
|--------------------------------------|
 \
  \
   |--------------------------------------|
   | LinkIntegerProperties                |
   |--------------------------------------|
   | integer           | Link             | <- Links::ID
   | integer           | Property         | <- LinkProperties::ID
   | integer           | Value            |
   |--------------------------------------|


   |--------------------------------------|
   | LinkStringProperties                 |
   |--------------------------------------|
   | integer           | Link             | <- Links::ID
   | integer           | Property         | <- LinkProperties::ID
   | varchar(255)      | Value            |
   |--------------------------------------|


   |--------------------------------------|
   | LinkByteArrayProperties              |
   |--------------------------------------|
   | integer           | Link             | <- Links::ID
   | integer           | Property         | <- LinkProperties::ID
   | bytea             | Value            |
   |--------------------------------------|

   [ other types as appropriate ]