Initial sketch for index-foreign-keys, refs #33

sqlite_utils/cli.py

@@ -217,6 +217,31 @@ def add_foreign_key(path, table, column, other_table, other_column):
         raise click.ClickException(e)
 
 
+
+@cli.command(name="index-foreign-keys")
+@click.argument(
+    "path",
+    type=click.Path(exists=True, file_okay=True, dir_okay=False, allow_dash=False),
+    required=True,
+)
+def index_foreign_keys(path):
+    """
+    Ensure every foreign key column has an index on it.
+    """
+    db = sqlite_utils.Database(path)
+    for table_name in db.table_names():
+        table = db[table_name]
+        existing_indexes = {
+            i.columns[0] for i in table.indexes if len(i.columns) == 1
+        }
+        for fk in table.foreign_keys:
+            if fk.column not in existing_indexes:
+                print("Creating index on {}.{}".format(
+                    table_name, fk.column
+                ))
+                table.create_index([fk.column])
+
+
 @cli.command(name="create-index")
 @click.argument(
     "path",