diff --git a/api/alembic/versions/0047_remove_old_vsp_functions.py b/api/alembic/versions/0047_remove_old_vsp_functions.py
new file mode 100644
index 0000000..04341b1
--- /dev/null
+++ b/api/alembic/versions/0047_remove_old_vsp_functions.py
@@ -0,0 +1,102 @@
+from alembic import op
+
+
+revision = "0047"
+down_revision = "0046"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # Verify that the implementations used by the API exist before removing
+    # historical signatures. CREATE OR REPLACE does not replace overloads.
+    op.execute(
+        """
+        DO $migration$
+        BEGIN
+            IF to_regprocedure(
+                'v3.add_vsp(integer, varchar, varchar, varchar, date, '
+                'varchar, integer, numeric, date, boolean, boolean, varchar, '
+                'integer, varchar, text, varchar, date)'
+            ) IS NULL THEN
+                RAISE EXCEPTION 'Current v3.add_vsp function is missing';
+            END IF;
+
+            IF to_regprocedure(
+                'v3.upd_vsp(integer, integer, varchar, varchar, varchar, '
+                'date, varchar, integer, numeric, date, boolean, boolean, '
+                'varchar, integer, varchar, text, varchar, date)'
+            ) IS NULL THEN
+                RAISE EXCEPTION 'Current v3.upd_vsp function is missing';
+            END IF;
+        END
+        $migration$;
+        """
+    )
+
+    # The first two may still have their temporary names in production.
+    for function_name in ("add_vsp", "add_vsp_1"):
+        op.execute(
+            f"""
+            DROP FUNCTION IF EXISTS v3.{function_name}(
+                integer, varchar, varchar, varchar, date, varchar,
+                integer, numeric, date, boolean, boolean, varchar,
+                integer, varchar, text, varchar, integer, varchar, date
+            ) RESTRICT
+            """
+        )
+
+    for function_name in ("add_vsp", "add_vsp_2"):
+        op.execute(
+            f"""
+            DROP FUNCTION IF EXISTS v3.{function_name}(
+                integer, varchar, varchar, varchar, date, varchar,
+                integer, numeric
+            ) RESTRICT
+            """
+        )
+
+    op.execute(
+        """
+        DROP FUNCTION IF EXISTS v3.upd_vsp(
+            integer, integer, varchar, varchar, varchar, date, varchar,
+            integer, numeric, date, boolean, boolean, varchar, integer,
+            varchar, text, varchar, integer, varchar, date
+        ) RESTRICT
+        """
+    )
+    op.execute(
+        """
+        DROP FUNCTION IF EXISTS v3.upd_vsp(
+            integer, integer, varchar, varchar, varchar, date, varchar,
+            integer, numeric
+        ) RESTRICT
+        """
+    )
+
+    op.execute(
+        """
+        DO $migration$
+        BEGIN
+            IF (
+                SELECT count(*)
+                FROM pg_proc AS p
+                JOIN pg_namespace AS n ON n.oid = p.pronamespace
+                WHERE n.nspname = 'v3' AND p.proname = 'add_vsp'
+            ) <> 1 OR (
+                SELECT count(*)
+                FROM pg_proc AS p
+                JOIN pg_namespace AS n ON n.oid = p.pronamespace
+                WHERE n.nspname = 'v3' AND p.proname = 'upd_vsp'
+            ) <> 1 THEN
+                RAISE EXCEPTION 'Unexpected v3.add_vsp or v3.upd_vsp overload remains';
+            END IF;
+        END
+        $migration$;
+        """
+    )
+
+
+def downgrade() -> None:
+    # The obsolete function bodies are not part of the current schema.
+    pass