[tarantool-patches] [PATCH] sql: disallow to rename space if it is referenced by view

[Nikita Pettik]

Before this patch it was allowed to rename space which is referenced by
a view. In turn, view contains SELECT statement in a raw form (i.e. as a
string) and it is not modified during renaming routine. Hence, after
renaming space still has referencing counter > 0, but no usage of view
is allowed (since execution of SELECT results in "Space does not
exist"). To avoid such situations, lets ban renaming space if its view
reference counter > 0.

Note that RENAME is ANSI extension, so different DBs behave in this case
in different ways - some of them allow to rename tables referenced by a
view (PostgreSQL), others - don't (Oracle).

Closes #3746
---
Branch: https://github.com/tarantool/tarantool/tree/np/gh-3746-view-rename
Issue: https://github.com/tarantool/tarantool/issues/3746

 src/box/alter.cc       | 6 ++++++
 test/sql/view.result   | 6 ++++++
 test/sql/view.test.lua | 3 +++
 3 files changed, 15 insertions(+)

diff --git a/src/box/alter.cc b/src/box/alter.cc
index 029da029e..f3b267401 100644
--- a/src/box/alter.cc
+++ b/src/box/alter.cc
@@ -1823,6 +1823,12 @@ on_replace_dd_space(struct trigger * /* trigger */, void *event)
 				  space_name(old_space),
 				  "can not convert a space to "
 				  "a view and vice versa");
+		if (strcmp(def->name, old_space->def->name) != 0 &&
+		    old_space->def->view_ref_count > 0)
+			tnt_raise(ClientError, ER_ALTER_SPACE,
+				  space_name(old_space),
+				  "can not rename space which is referenced by "
+				  "view");
 		/*
 		 * Allow change of space properties, but do it
 		 * in WAL-error-safe mode.
diff --git a/test/sql/view.result b/test/sql/view.result
index b211bcb2e..8adbe568c 100644
--- a/test/sql/view.result
+++ b/test/sql/view.result
@@ -69,6 +69,12 @@ box.schema.create_space('view', {view = true})
 ---
 - error: Illegal parameters, unexpected option 'view'
 ...
+-- Space referenced by a view can't be renamed.
+box.sql.execute("ALTER TABLE t1 RENAME TO new_name;")
+---
+- error: 'Can''t modify space ''T1'': can not rename space which is referenced by
+    view'
+...
 -- View can be created via straight insertion into _space.
 sp = box.schema.create_space('test');
 ---
diff --git a/test/sql/view.test.lua b/test/sql/view.test.lua
index a6269a1bf..ba4d0bb2c 100644
--- a/test/sql/view.test.lua
+++ b/test/sql/view.test.lua
@@ -33,6 +33,9 @@ box.space._space:replace(v1);
 -- Views can't be created via space_create().
 box.schema.create_space('view', {view = true})
 
+-- Space referenced by a view can't be renamed.
+box.sql.execute("ALTER TABLE t1 RENAME TO new_name;")
+
 -- View can be created via straight insertion into _space.
 sp = box.schema.create_space('test');
 raw_sp = box.space._space:get(sp.id):totable();
-- 
2.15.1