git - git的合并策略是什么？

Question

可能重复：
你什么时候使用不同的 git 合并策略？

当 git 合并我正在处理的文件时，我看到：

Merge made by the 'recursive' strategy

递归策略到底是什么？还有哪些其他策略（如果有）？使用其中一个有什么好处？不同的策略有不同的表现吗？或者两种不同的策略会导致不同的合并结果？

Answer 1

来自git help merge：

   The merge mechanism (git-merge and git-pull commands) allows the
   backend merge strategies to be chosen with -s option. Some strategies
   can also take their own options, which can be passed by giving
   -X<option> arguments to git-merge and/or git-pull.

   resolve
       This can only resolve two heads (i.e. the current branch and
       another branch you pulled from) using a 3-way merge algorithm. It
       tries to carefully detect criss-cross merge ambiguities and is
       considered generally safe and fast.

   recursive
       This can only resolve two heads using a 3-way merge algorithm. When
       there is more than one common ancestor that can be used for 3-way
       merge, it creates a merged tree of the common ancestors and uses
       that as the reference tree for the 3-way merge. This has been
       reported to result in fewer merge conflicts without causing
       mis-merges by tests done on actual merge commits taken from Linux
       2.6 kernel development history. Additionally this can detect and
       handle merges involving renames. This is the default merge strategy
       when pulling or merging one branch.

       The recursive strategy can take the following options:

       ours
           This option forces conflicting hunks to be auto-resolved
           cleanly by favoring our version. Changes from the other tree
           that do not conflict with our side are reflected to the merge
           result.

           This should not be confused with the ours merge strategy, which
           does not even look at what the other tree contains at all. It
           discards everything the other tree did, declaring our history
           contains all that happened in it.

       theirs
           This is opposite of ours.

       subtree[=path]
           This option is a more advanced form of subtree strategy, where
           the strategy makes a guess on how two trees must be shifted to
           match with each other when merging. Instead, the specified path
           is prefixed (or stripped from the beginning) to make the shape
           of two trees to match.

   octopus
       This resolves cases with more than two heads, but refuses to do a
       complex merge that needs manual resolution. It is primarily meant
       to be used for bundling topic branch heads together. This is the
       default merge strategy when pulling or merging more than one
       branch.

   ours
       This resolves any number of heads, but the resulting tree of the
       merge is always that of the current branch head, effectively
       ignoring all changes from all other branches. It is meant to be
       used to supersede old development history of side branches. Note
       that this is different from the -Xours option to the recursive
       merge strategy.

   subtree
       This is a modified recursive strategy. When merging trees A and B,
       if B corresponds to a subtree of A, B is first adjusted to match
       the tree structure of A, instead of reading the trees at the same
       level. This adjustment is also done to the common ancestor tree.