Re: [Tarantool-patches] [PATCH v4 5/6] box: disallow to modify format of a view

[Vladislav Shpilevoy <v.shpilevoy@tarantool.org>]

Thanks for the patch!

On 11.09.2020 23:51, Roman Khabibov wrote:
> Disallow to modify format and field_count of a view.

See 4 comments below in addition to Nikita's comments.

1. That should be in a different branch, to emphasize that
it is a separate bug, which we will need to merge into 2.4
and 2.5 as well.

> Needed for #3075
> ---
>  src/box/alter.cc                          |  8 ++++
>  test/box/view-dont-modify-format.result   | 51 +++++++++++++++++++++++
>  test/box/view-dont-modify-format.test.lua | 18 ++++++++
>  3 files changed, 77 insertions(+)
>  create mode 100644 test/box/view-dont-modify-format.result
>  create mode 100644 test/box/view-dont-modify-format.test.lua
> 
> diff --git a/src/box/alter.cc b/src/box/alter.cc
> index ba96d9c62..3bfbb690a 100644
> --- a/src/box/alter.cc
> +++ b/src/box/alter.cc
> @@ -2441,6 +2441,14 @@ on_replace_dd_space(struct trigger * /* trigger */, void *event)
>  				  "view");
>  			return -1;
>  		}
> +		if (def->opts.is_view && (def->field_count !=
> +		    old_space->def->field_count)) {

2. The () around != is not needed.

> +			diag_set(ClientError, ER_ALTER_SPACE,
> +				  space_name(old_space),
> +				  "can not modify format or field_count of a "
> +				  "view");
> +			return -1;
> +		}
>  		/*
>  		 * Allow change of space properties, but do it
>  		 * in WAL-error-safe mode.
> diff --git a/test/box/view-dont-modify-format.result b/test/box/view-dont-modify-format.result
> new file mode 100644
> index 000000000..c130db49c
> --- /dev/null
> +++ b/test/box/view-dont-modify-format.result
> @@ -0,0 +1,51 @@
> +-- test-run result file version 2
> +--
> +-- Make sure we can't modify a view format.
> +--
> +box.execute("CREATE TABLE t1 (a INT PRIMARY KEY);")
> + | ---
> + | - row_count: 1
> + | ...
> +box.execute("CREATE VIEW v AS SELECT * FROM t1;")
> + | ---
> + | - row_count: 1
> + | ...
> +view = box.space._space.index[2]:select('V')[1]:totable()

3. You could use box.space.V:format().

> +f = {type = 'string', nullable_action = 'none', name = 'C', is_nullable = true}
> + | ---
> + | ...
> +table.insert(view_format, f)
> + | ---
> + | ...
> +view[5] = 3
> + | ---
> + | ...
> +view[7] = view_format

4. You can use space:alter() method instead of raw modification
of _space. Although it is not available on 2.4.

> + | ---
> + | ...
> +box.space._space:replace(view)
> + | ---
> + | - error: 'Can''t modify space ''V'': can not modify format or field_count of a view'
> + | ...
> +
> +view = box.space.V
> + | ---
> + | ...
> +view:format({})
> + | ---
> + | - error: 'Can''t modify space ''V'': can not modify format or field_count of a view'
> + | ...
> +
> +box.execute("DROP VIEW v;")
> + | ---
> + | - row_count: 1
> + | ...
> +box.execute("DROP TABLE t1;")
> + | ---
> + | - row_count: 1
> + | ...