Re: [PATCH v4 00/10] Sparse index: delete ignored files outside sparse cone

>
> On 8/27/2021 6:01 PM, Elijah Newren wrote:
> > Sorry, one more thing...
> >
> > On Fri, Aug 27, 2021 at 2:56 PM Elijah Newren <newren@gmail.com> wrote:
> >>
> >> On Tue, Aug 24, 2021 at 2:51 PM Derrick Stolee via GitGitGadget
> >> <gitgitgadget@gmail.com> wrote:
> >
> >>>   8:  febef675f05 !  9:  c19d93ec5d7 sparse-checkout: clear tracked sparse dirs
> >>>      @@ Commit message
> >>>           the sparse directory. This depends on the indexed version of the file,
> >>>           so the sparse directory must be expanded.
> >>>
> >>>      +    We must take special care to look for untracked, non-ignored files in
> >>>      +    these directories before deleting them. We do not want to delete any
> >>>      +    meaningful work that the users were doing in those directories and
> >>>      +    perhaps forgot to add and commit before switching sparse-checkout
> >>>      +    definitions. Since those untracked files might be code files that
> >>>      +    generated ignored build output, also do not delete any ignored files
> >>>      +    from these directories in that case. The users can recover their state
> >>>      +    by resetting their sparse-checkout definition to include that directory
> >>>      +    and continue. Alternatively, they can see the warning that is presented
> >>>      +    and delete the directory themselves to regain the performance they
> >>>      +    expect.
> >
> > Will deleting the directory regain the performance they expect, or is
> > another step needed?  In other worse, will the sparsification of the
> > paths under the no-longer-needed directory into a sparse directory
> > entry just happen automatically as part of some other command like
> > commit/add, or do they need to manually run `git sparse-checkout
> > reapply`?
>
> If the directory is gone, then their performance returns to as they
> expect, since the next Git command will not need to expand the index
> to detect the difference between tracked, untracked, and ignored files
> within the sparse directory.
>
> (Recall that the index is stored as sparse even if it expands to a
> full one in-memory during execution.)