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examples/fs/README.md

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+# Recursive Traversal Using [CTE](https://en.wikipedia.org/wiki/Hierarchical_and_recursive_queries_in_SQL#Common_table_expression)
+
+In this example, we create a file system with a tree structure, and want to query all "undeleted" files.
+A file is considered as "deleted", if it's marked as "deleted" (a bool field), or any of its parents is
+marked as "deleted".
+
+Given the following tree structure:
+
+```console
+a/
+├─ b/
+│  ├─ ba
+│  ├─ bb
+│  └─ bc (deleted)
+├─ c/ (deleted)
+│  ├─ ca
+│  └─ cb
+└─ d (deleted)
+```
+
+Query "undeleted" files should return the following structure:
+
+```console
+a/
+└─ b/
+   ├─ ba
+   └─ bb
+```
+
+As you can see, in order to check if "cb" (or "ca") is "deleted", we need to "look behind" recursively
+until we find a "deleted" parent, or reach the root ("a").
+
+
+### Generate Assets
+
+```console
+go generate ./...
+```
+
+### Run Example
+
+```console
+go test
+```