Recently I have been asked to design a perl module (backed by a database) to provide access to a data, which is essentially of a tree structure type. For example, the data looks like:
Child Node 1/
Sub Child Node 1/
My database table has the following columns & data:
id | node_name | parent_id
1 | Parent Node1 | 0
2 | Child Node1 | 1
3 | Sub Child Node1 | 2
4 | Leaf1 | 3
id is autogenerated primary key
parent_id is the "id" of the parent row
node_name is the name of the node.
Apart from the regular new(), node_name(), save() and delete() functions, I plan to provide a parent(), which would query the database and return the parent of the given node (as an object.)
The class will be used to list leaf/node(s), for a given node and also display some sort of heirarchial path (or bread crumb) to the given leaf (by appending the parent's node_name() till parent() returns null)
I seek your advice for:
1. is there an optimal way to design a database table to represent an tree structure ?
2. can I provide a better design to access the heirarchial path without incurring a performance penalty ?
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