Rebase Streams

If you have a topic and parent stream that both contain changes, and you want to update the topic stream with the changes from its parent, you can rebase the topic stream.

Key Facts

• Rebase updates the content of the topic stream with the tip of the parent stream (or an earlier version).

• Rebase merges the changes from the selected parent stream version, with all the changesets in the topic stream, into a single changeset on the topic stream.

• Rebase is simpler and quicker than merging the streams. The rebase is performed in the repository and not via the work area.

• Rebase is particularly useful when development work on a topic stream is taking a long time and you want to test your code with the latest updates in the parent stream.

• Rebase makes reviews of changes simpler.

• Rebase only works if there are no conflicts between the topic and mainline streams.

Scenario

1. A topic stream is created from a parent stream. Deliveries are made to both streams, which creates multiple changesets:

• Parent stream changesets: p1, p2, p3

• Topic stream changesets: t1,t2

  

2. Solution 1: merge

• Merging changes from the parent into the topic stream via the work area creates a new changeset, t3, in the topic stream that includes all the changes from the parent stream.

• The pull request for the topic stream includes the results of the merge, which makes it hard to see the real changes in the topic stream.

  

3. Solution 2: rebase

• Rebasing merges all the changesets in the parent stream (p1, p2, p3) into a new changeset on the topic stream, t1’.

• Rebase then merges the topic stream changesets (t1, t2) into a new changeset, t2’.

• The pull request for the topic stream looks cleaner as it does not include the changes from p2 and p3 in the parent stream.