Re: [PATCH v3 06/10] Documentation/config/pack.txt: advertise 'pack.writeReverseIndex'

From: Jeff King <peff@peff.net>
Date: Jan 30, 2021, 08:41 UTC
Message-ID: <YBUbu67CdryFdTXK@coredump.intra.peff.net>
In-Reply-To: <YBNiNAVhlRpNKzr+@nand.local>

On Thu, Jan 28, 2021 at 08:17:40PM -0500, Taylor Blau wrote:

Show 20 quoted lines

> On Thu, Jan 28, 2021 at 07:30:56PM -0500, Jeff King wrote:
> > On Mon, Jan 25, 2021 at 06:37:34PM -0500, Taylor Blau wrote:
> >
> > > +pack.writeReverseIndex::
> > > +	When true, git will write a corresponding .rev file (see:
> > > +	link:../technical/pack-format.html[Documentation/technical/pack-format.txt])
> > > +	for each new packfile that it writes in all places except for
> > > +	linkgit:git-fast-import[1] and in the bulk checkin mechanism.
> > > +	Defaults to false.
> >
> > We may want to teach fast-import about this, too, but I think it's OK to
> > draw the line here for now (it's already reasonably well known that the
> > generated packs aren't amazing and benefit from repacking).
> 
> Maybe this was worth explaining in the documentation, but this choice
> was intentional. I'm not aware of any use-case that keeps the packs
> generated by fast-import around for very long (i.e., I'd expect any 'git
> fast-import' to be pretty quickly followed by a 'git repack -ad'), so I
> don't think we'd want to spend time generating a reverse index for a
> pack structure that we're about to immediately discard.

One case where I imagine they are kept is in remote-helpers that use the import/export mechanism (e.g., something interacting with remote-hg). I suspect people there just live with the somewhat lousy packs, and then perhaps occasionally "git repack -adf". That would give them .rev files then, too.

But as I said, I think it's OK to ignore this for now. If somebody with an interest in fast-import wants to add support later, they can.

-Peff