diff --git a/swh/core/db/__init__.py b/swh/core/db/__init__.py
--- a/swh/core/db/__init__.py
+++ b/swh/core/db/__init__.py
@@ -19,6 +19,39 @@
 psycopg2.extras.register_uuid()
 
 
+def escape(data):
+    if data is None:
+        return ''
+    if isinstance(data, bytes):
+        return '\\x%s' % binascii.hexlify(data).decode('ascii')
+    elif isinstance(data, str):
+        return '"%s"' % data.replace('"', '""')
+    elif isinstance(data, datetime.datetime):
+        # We escape twice to make sure the string generated by
+        # isoformat gets escaped
+        return escape(data.isoformat())
+    elif isinstance(data, dict):
+        return escape(json.dumps(data))
+    elif isinstance(data, list):
+        return escape("{%s}" % ','.join(escape(d) for d in data))
+    elif isinstance(data, psycopg2.extras.Range):
+        # We escape twice here too, so that we make sure
+        # everything gets passed to copy properly
+        return escape(
+            '%s%s,%s%s' % (
+                '[' if data.lower_inc else '(',
+                '-infinity' if data.lower_inf else escape(data.lower),
+                'infinity' if data.upper_inf else escape(data.upper),
+                ']' if data.upper_inc else ')',
+            )
+        )
+    elif isinstance(data, enum.IntEnum):
+        return escape(int(data))
+    else:
+        # We don't escape here to make sure we pass literals properly
+        return str(data)
+
+
 class BaseDb:
     """Base class for swh.*.*Db.
 
@@ -99,37 +132,6 @@
             item_cb (fn): optional function to apply to items's entry
 
         """
-        def escape(data):
-            if data is None:
-                return ''
-            if isinstance(data, bytes):
-                return '\\x%s' % binascii.hexlify(data).decode('ascii')
-            elif isinstance(data, str):
-                return '"%s"' % data.replace('"', '""')
-            elif isinstance(data, datetime.datetime):
-                # We escape twice to make sure the string generated by
-                # isoformat gets escaped
-                return escape(data.isoformat())
-            elif isinstance(data, dict):
-                return escape(json.dumps(data))
-            elif isinstance(data, list):
-                return escape("{%s}" % ','.join(escape(d) for d in data))
-            elif isinstance(data, psycopg2.extras.Range):
-                # We escape twice here too, so that we make sure
-                # everything gets passed to copy properly
-                return escape(
-                    '%s%s,%s%s' % (
-                        '[' if data.lower_inc else '(',
-                        '-infinity' if data.lower_inf else escape(data.lower),
-                        'infinity' if data.upper_inf else escape(data.upper),
-                        ']' if data.upper_inc else ')',
-                    )
-                )
-            elif isinstance(data, enum.IntEnum):
-                return escape(int(data))
-            else:
-                # We don't escape here to make sure we pass literals properly
-                return str(data)
 
         read_file, write_file = os.pipe()