Re: [PATCH 2/2] line-log: avoid unnecessary full tree diffs

SZEDER Gábor [off-list ref] writes:

So basically the line-level log computes a full tree diff for each
commit-parent pair in step (1) to be used for rename detection in step
(4) in the off chance that an interesting path is missing from the
parent.

Good explanation.  As we are not supporting swapping of two (or
more) files, we only need rename processing when a path we have been
inspecting disappears, at which point it is worth spending cycles to
see where the path used to be in the parent commit.

[1] Line-level log's rename following is quite similar to 'git log
    --follow path', with the notable differences that it does handle
    multiple paths at once as well, and that it doesn't show the
    commit performing the rename if it's an exact rename.

Yeah, it's one of the reasons why "log --follow" is not (yet) a
serious "feature" but merely a "checkbox item".

[2] This slowness might not have been apparent initially, because back
    when the line-level log feature was introduced rename detection

s/introduced/&,/

    was not yet enabled by default; 12da1d1f6f (Implement line-history
    search (git log -L), 2013-03-28) and 5404c116aa (diff: activate
    diff.renames by default, 2016-02-25).

s/\.$/ are about 3 years apart&/ or something like that to make what
follows the semicolon a full sentence?