Nice nick, надо бы наведаться в Питер к вам :)

Good issue tracker have no need in subtasks. Just implement good UI for relations.

Actually, our model supports subtasking, since we import meta-issues and subtasks from JIRA. The old UI displayed subtasks as links, that covered all our internal requirements coming from the TeamCity team. The new UI doesn't present subtasks anyhow, and already nobody cares of that. So the question is about presentation only: what it should be and should it be at all?

Common pattern of using subtasks is split one big task by small subtasks and perform it step-by-step. Then all subtasks is closed the big task is can be closed too. But better to have 'check list' support, i suppose. To solve task, you must have solve items in check list.

Another one pattern – is collecting issues from users grouped by one common task. For instance big task – problems in video convertation, and subtasks - can't convert mov, can't convert h264 etc. In JIRA it better what using of components, cos reporters (especialy from email) will not set component and tasks are looses. Also you can look at view screen of big issue and see progress of solving subtasks? instead of use filters (in JIRA filters is very hard to use). So, subtasking is ways to group and search issues.

Subtaks creates big limitations in data model. All patterns described actually should be realized by good UI representation of linkage and some additional event handling mechanic.

+1 for subtasks as links + UI + with maybe some extra logic

Very odd. I thought, that such request would make much more votes, than the current amount.

UPD:
Good people want to prove me wrong. :)

Guys, what about show substasks as a tree? We can either upgrade 1-line mode or add new "tree mode" to issues screen.

I made a proposal here how it might be implemented http://devnet.jetbrains.net/message/5319867. See links.

when you have more than two level of tree complexity, your tasks starting to shuffle, and it's a way hard to keep in mind the state of the top level task as it becomes composite. It would be nice to see your tasks organized into trees in task list.

Yehuuuuuu!!!!

This is a major blocker for us - we've got a largish JIRA install that we are considering moving to YouTrack, but the lack of subtasks or an easy way of linking YouTrack tasks under import from JIRA is a showstopper..

Is there an EAP version of YouTrack 3.0.5 or 3.1 available anywhere that has those features? I'm willing to test and run bleeding edge versions if they are available..

Jens, thank you for your interest to YouTrack. This feature is in progress yet, but i should say that it's almost done. I guess it will be available in version 3.2 (it aprox. 1 or months ahead). There is no any EAP for now. Anyway i'll post a comment with the link when the build with this feature will be available.

Use-case from me would be roughly estimating given release backlog using work break-down structure (WBS) approach. We used Excel Spreadsheet (e.g. Jira would be very slow and inconvenient) for that task because (of simplicity):
* You can create sub-tasks when you break the work piece into smaller parts for estimation
* Time to enter new feature = time to type it (you concentrate on your WBS, not on the tool)
* All can be done with a keyboard (no mouse clicking)
* The whole picture is visible instantly (you can scroll spreadsheet without the need to click through pages)
* Sub-totals and grand totals for estimates are instantly available
Of course it's a duplication of work because later-on after estimation session we had to copy the WBS created into our project tracking tool.
That would be a great advantage for YouTrack to incorporate the usability of a spreadsheet mentioned above, and looks like support of sub-tasks could be part of it.

Roman, thank you for the detailed use-case. Now we are developing a Scrum board feature - JT-1629. Feel free to vote

+1
I want to have some provision to create sub task for an issue. Lets say I have an issue which is reproducible in two versions of our product. So I want to track the life of this issue in different versions separately but not as a different issue. So I will create two sub tasks under this issue, one for each version.

+1

So far the parent-child relationship can be emulated with a custom Issue Link Type like "Contain", which may have "contain" as Outward Name, and "is part of" as Inward Name.
This will allow to establish the relationship, but unfortunately it will be hardly visible in YouTrack UI.

YouTrack Fascination EAP is open! Substasks support is already there, as well as a Scrum Board!