From: Junio C Hamano <gitster@pobox.com>
Date: Fri, 31 Jan 2020 18:08:36 GMT
Subject: Re: [RFC PATCH] diff: only prefetch for certain output formats
Message-ID: <xmqqeevfbisb.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <20200131001416.GB2394563@coredump.intra.peff.net>

Jeff King <peff@peff.net> writes:

> fetches anything at all). I.e., for "diff -M -p", you'd want:
>
>   1. diffcore_std() sees "-p" and fetches everything
>
>   2. diffcore_rename() sees there's nothing we don't already have
>
> rather than:
>
>   1. diffcore_rename() fetches a few blobs to do rename detection
>
>   2. diffcore_std() fetches a few more blobs that weren't rename
>      candidates, but we need for "-p"

Hmph, a pure rename only change will cause no blobs transferred with
the latter (because there is no content change for "-p" to report,
and the rename detection for R100 paths would be done at the object
name level), but all blobs in filepairs (before rename matches A/D
up) with the former, no?