Where is the parent/child relationship between nodes stored in the database? I am migrating a site from one CMS to Drupal and I'm working on migrating link structures over correctly. This is something I am going to have to automate because there are over 3,500 nodes of content that I am migrating over.

I can't seem to find in Drupal 8's database schema where the relationship between parent and children nodes are stored. I have been looking for something like a 'pid' or a 'cid' column (parent id and child id, respectively), but I can't seem to find a column like that in the schema.

I know you can make nodes children of other nodes, so I know it has to store this information somewhere. If someone could tell me what table and column this information gets stored in I would greatly appreciate that.

Drupal 8 Database Schema
The simple answer is, there is none.

Nodes in Drupal does not have a hierarchy, it's other things on top of it that allow you to do that, depending on the use case:

Menu links: You can have menu trees and each points to a node, but the nodes themself don't really about that. Some parts might look like it does, e.g. breadcrumb but that is simply based on the path.

Book module: This allows to create a book (basically a hierarchic structure of nodes), but this only makes sense for specific cases, e.g. structured documentation that has chapters and so on.

References: In many cases, nodes are just connected between each other with reference fields, which you could make look like a hierarchy.

Taxonomy: You can have Terms with a hierarchy and reference those from nodes, but again by default that doesn't give you anything hierarchy-like unless you start to combine with with path aliases or so.

=> Content in Drupal is very different from how most other sites handle it and you can't just convert it 1:1.