mergecommits

Merge commits are commits produced when integrating changes from one branch into another in a version control workflow, most commonly in Git. A merge commit ties together the histories of the merged branches by recording one or more parent commits, typically two for a standard two-branch merge. This creates a non-linear history that preserves the existence of feature branches and the point at which their work was combined.

In Git, a merge results in a merge commit when the merge is not a simple fast-forward. A fast-forward merge moves the destination branch pointer forward to the latest commit on the source branch without creating a new commit, yielding a linear history. By contrast, a non-fast-forward merge creates a merge commit to record the intersection of histories. An octopus merge, which combines more than two branches, also produces a merge commit with multiple parents.

Common options related to merge commits include --no-ff, which forces the creation of a merge commit even if a fast-forward would be possible, and --ff-only, which requires a fast-forward merge and will refuse otherwise. The default behavior can be configured in workflows and merge tools, such as those on Git hosting services, which may offer choices like “Create a merge commit,” “Squash and merge,” or “Rebase and merge.”

Viewing and working with merge commits can involve commands that highlight merges, such as git log --merges or git log --graph. The presence of merge commits can aid in understanding integration points and project history, but may also add complexity to history traversal and blame. Teams balance their use of merge commits against preferences for a linear history or a clearly documented merge chronology.