Panic on dolt_diff_* with generated column

[senuphtyz]

Using a table with a generated column panics trying to diff inserted data.
I used version 1.44.1 to produce this error.

Steps to produce:

1. Create a table with a generated column

CREATE TABLE `users` (
  `id` int NOT NULL AUTO_INCREMENT,
  `login` varchar(255) NOT NULL,
  `title` varchar(255),
  `first_name` varchar(255) NOT NULL,
  `last_name` varchar(255) NOT NULL,
  `full_name` varchar(255) GENERATED ALWAYS AS (lower(concat(`first_name`,' ',`last_name`))),
  PRIMARY KEY (`id`)
);

3. Commit schema changes

call dolt_commit('-A', '-m', 'a commit message');

4. Insert data into table

insert into users SET id=1, login="login", title="title",first_name="first_name", last_name="last_name";

5. Try generating a diff

select * from dolt_diff_users;

Results in:

panic: runtime error: index out of range [4] with length 4

goroutine 39 [running]:
github.com/dolthub/dolt/go/store/prolly/tree.GetField({0x36ec990?, 0xc000f9e820?}, {{0xc000660a70, 0x4, 0x4}, {0xc00091e800, 0x4, 0x4}, {0x36f3bc0, 0xc00132c420}, ...}, ...)
        github.com/dolthub/dolt/go/store/prolly/tree/prolly_fields.go:41 +0x3a75
github.com/dolthub/dolt/go/libraries/doltcore/sqle/dtables.ProllyRowConverter.putFields({{0x378a420, 0xc000a8e780}, {0x378a420, 0xc000a8e080}, {0xc000660a50, 0x1, 0x1}, {0xc00012cb10, 0x5, 0x5}, ...}, ...)
        github.com/dolthub/dolt/go/libraries/doltcore/sqle/dtables/prolly_row_conv.go:119 +0xe5
github.com/dolthub/dolt/go/libraries/doltcore/sqle/dtables.ProllyRowConverter.PutConverted({{0x378a420, 0xc000a8e780}, {0x378a420, 0xc000a8e080}, {0xc000660a50, 0x1, 0x1}, {0xc00012cb10, 0x5, 0x5}, ...}, ...)
        github.com/dolthub/dolt/go/libraries/doltcore/sqle/dtables/prolly_row_conv.go:111 +0x268
github.com/dolthub/dolt/go/libraries/doltcore/sqle/dtables.prollyDiffIter.getDiffTableRow({{{{{...}, {...}, 0x0, 0x0, 0x0, {...}}, {0x36fe490, 0xc000b8d040}, {{...}, {...}, ...}}, ...}, ...}, ...)
        github.com/dolthub/dolt/go/libraries/doltcore/sqle/dtables/diff_iter.go:429 +0x1c9
github.com/dolthub/dolt/go/libraries/doltcore/sqle/dtables.prollyDiffIter.makeDiffRowItr({{{{{...}, {...}, 0x0, 0x0, 0x0, {...}}, {0x36fe490, 0xc000b8d040}, {{...}, {...}, ...}}, ...}, ...}, ...)
        github.com/dolthub/dolt/go/libraries/doltcore/sqle/dtables/diff_iter.go:372 +0x15a
github.com/dolthub/dolt/go/libraries/doltcore/sqle/dtables.prollyDiffIter.queueRows.func1({0x36ec990, 0xc000f9e820}, {{0xc000234394, 0x6, 0x20}, {0x0, 0x0, 0x0}, {0xc00023436c, 0x1b, ...}, ...})
        github.com/dolthub/dolt/go/libraries/doltcore/sqle/dtables/diff_iter.go:338 +0x78
github.com/dolthub/dolt/go/store/prolly.DiffMaps.makeDiffCallBack.func1({0x36ec990?, 0xc000f9e820?}, {{0xc000234394, 0x6, 0x20}, {0x0, 0x0, 0x0}, {0xc00023436c, 0x1b, ...}, ...})
        github.com/dolthub/dolt/go/store/prolly/tuple_map.go:165 +0x103
github.com/dolthub/dolt/go/store/prolly/tree.DiffOrderedTrees[...]({_, _}, {{{0x4c, 0x0, 0x44, 0x2, 0x0}, {0x40, 0x0, 0x38, ...}, ...}, ...}, ...)
        github.com/dolthub/dolt/go/store/prolly/tree/map.go:70 +0x2a5
github.com/dolthub/dolt/go/store/prolly.DiffMaps({_, _}, {{{{0x4c, 0x0, 0x44, 0x2, 0x0}, {0x40, 0x0, 0x38, ...}, ...}, ...}, ...}, ...)
        github.com/dolthub/dolt/go/store/prolly/tuple_map.go:115 +0x176
github.com/dolthub/dolt/go/libraries/doltcore/sqle/dtables.prollyDiffIter.queueRows({{{{{...}, {...}, 0x0, 0x0, 0x0, {...}}, {0x36fe490, 0xc000b8d040}, {{...}, {...}, ...}}, ...}, ...}, ...)
        github.com/dolthub/dolt/go/libraries/doltcore/sqle/dtables/diff_iter.go:337 +0xa5
github.com/dolthub/dolt/go/libraries/doltcore/sqle/dtables.newProllyDiffIter.func1()
        github.com/dolthub/dolt/go/libraries/doltcore/sqle/dtables/diff_iter.go:309 +0x35
created by github.com/dolthub/dolt/go/libraries/doltcore/sqle/dtables.newProllyDiffIter in goroutine 1
        github.com/dolthub/dolt/go/libraries/doltcore/sqle/dtables/diff_iter.go:308 +0xb2d

[timsehn]

Oooo. Good bug that generated column is causing issues for us. We'll at least make it not panic today. Hopefully, we'll be able to produce teh proper diff tables as well today but that may be a bit harder.

[jycor]

Hey @senuphtyz, thanks for reporting this issue! We have merged the fix to dolt main to make this not panic.
Currently, the diff for virtual generated columns will just be NULL. Ideally, we'd be able to show the value but that isn't near at hand. As a workaround, having the generated columns be stored will produce a diff.

A release with the fix will be out later this week!
Please let us know how it works for you, and if there are any other issues!

[bpf120]

@senuphtyz , thanks for using Dolt and reporting this issue. We'd love to learn about your use case. If want to share, you can email me or swing by our Discord.