As a user I wondered what the diff algorithms are about. Offer at least a basic explanation on the differences of the diff algorithms. Signed-off-by: Stefan Beller <sbeller@xxxxxxxxxx> --- Documentation/diff-options.txt | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-) diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt index f466600972f..0d765482027 100644 --- a/Documentation/diff-options.txt +++ b/Documentation/diff-options.txt @@ -94,16 +94,34 @@ diff" algorithm internally. Choose a diff algorithm. The variants are as follows: + -- -`default`, `myers`;; - The basic greedy diff algorithm. Currently, this is the default. `minimal`;; - Spend extra time to make sure the smallest possible diff is - produced. + A diff as produced by the basic greedy algorithm described in + link:http://www.xmailserver.org/diff2.pdf[An O(ND) Difference Algorithm and its Variations] +`default`, `myers`;; + The same algorithm as `minimal`, extended with a heuristic to + reduce extensive searches. Currently, this is the default. `patience`;; - Use "patience diff" algorithm when generating patches. + Use "patience diff" algorithm when generating patches. This + matches the longest common subsequence of unique lines on + both sides, recursively. It obtained its name by the way the + longest subsequence is found, as that is a byproduct of the + patience sorting algorithm. If there are no unique lines left + it falls back to `myers`. Empirically this algorithm produces + a more readable output for code, but it does not garantuee + the shortest output. `histogram`;; - This algorithm extends the patience algorithm to "support - low-occurrence common elements". + This algorithm re-implements the `patience` algorithm with + "support of low-occurrence common elements" and only picks + one element of the LCS for the recursion. It is often the + fastest, but in cornercases (when there are many longest + common subsequences of the same length) it produces bad + results as seen in: + + seq 1 100 >one + echo 99 > two + seq 1 2 98 >>two + git diff --no-index --histogram one two + -- + For instance, if you configured diff.algorithm variable to a -- 2.18.0.345.g5c9ce644c3-goog
