Finding circular dependencies in your SQLAlchemy data scheme

find_circular_dependencies.py

from collections import defaultdict
dependencies = defaultdict(set)

#use your metadata object here
for t in metadata.sorted_tables:

    for fkey in t.foreign_key_constraints:
        dependencies[t.name].add(fkey.referred_table.name)

def find_circular_dependencies(dependencies,verbose = False):

    def walk_graph(name,path = None,tabs = 0):
        if path is None:
            path = []
        for dependency in dependencies[name]:
            if verbose:
                print "  "*tabs,dependency
            if dependency in path:
                print "Circular dependency:","->".join(path+[dependency])
                continue
            walk_graph(dependency,path+[dependency],tabs = tabs+1)

    for name in dependencies.keys():
        walk_graph(name)

#will print your circular dependencies
find_circular_dependencies(dependencies)