refactor(schema): fan desired-state schema out to one file per table (#8131)

schema/functions/enforce_community_tombstone.sql

@@ -0,0 +1,28 @@
+CREATE FUNCTION enforce_community_tombstone() RETURNS TRIGGER
+LANGUAGE plpgsql AS $$
+DECLARE
+    executor_community TEXT := current_setting('buzz.deletion_executor_community', true);
+    executor_generation TEXT := current_setting('buzz.deletion_fence_generation', true);
+    expected_generation BIGINT;
+BEGIN
+    IF TG_OP = 'DELETE' THEN
+        IF OLD.deletion_state <> 'active' OR OLD.deleted_at IS NOT NULL THEN
+            RAISE EXCEPTION 'community tombstones are permanent'
+                USING ERRCODE = 'object_not_in_prerequisite_state';
+        END IF;
+        RETURN OLD;
+    END IF;
+    expected_generation := CASE WHEN NEW.deletion_fence_generation > OLD.deletion_fence_generation
+        THEN NEW.deletion_fence_generation ELSE OLD.deletion_fence_generation END;
+    IF executor_community = OLD.id::text AND executor_generation ~ '^[0-9]+$'
+       AND executor_generation::BIGINT = expected_generation THEN RETURN NEW; END IF;
+    IF OLD.deletion_state <> 'active' OR NEW.deletion_state <> OLD.deletion_state
+       OR NEW.deletion_fence_generation <> OLD.deletion_fence_generation
+       OR NEW.deleted_at IS DISTINCT FROM OLD.deleted_at THEN
+        RAISE EXCEPTION 'community tombstone mutation rejected: community % generation %',
+            OLD.id, OLD.deletion_fence_generation
+            USING ERRCODE = 'object_not_in_prerequisite_state';
+    END IF;
+    RETURN NEW;
+END
+$$;