Re: Should I store large text files on Git LFS?

From: Jeff King <peff@peff.net>
Date: Jul 25, 2017, 21:13 UTC
Message-ID: <20170725211300.vwlpioy5jes55273@sigill.intra.peff.net>
In-Reply-To: <xmqq7eywutlt.fsf@gitster.mtv.corp.google.com>

On Tue, Jul 25, 2017 at 01:52:46PM -0700, Junio C Hamano wrote:

Show 14 quoted lines

> Jeff King <peff@peff.net> writes:
> 
> > As you can see, core.bigfilethreshold is a pretty blunt instrument. It
> > might be nice if .gitattributes understood other types of patterns
> > besides filenames, so you could do something like:
> >
> >   echo '[size > 500MB] delta -diff' >.gitattributes
> >
> > or something like that. I don't think it's come up enough for anybody to
> > care too much about it or work on it.
> 
> But attributes is about paths, at which a blob may or may not exist,
> so it is a bad fit to add conditionals that are based on sizes and
> types.

Do attributes _have_ to be about paths? In practice we often use them to describe objects, and paths are just the only mechanism we give to refer to objects. But it is not actually a correct or rigorous mechanism in some cases. For example, imagine I have a .gitattributes with:

  foo -delta
  bar delta

and then imagine I have a tree with both "foo" and "bar" pointing to the same blob. When I run pack-objects, it wants to know whether to delta the object. What should it do?

The delta decision is really a property of the object. But the only mechanism we give for selecting an object is by path, which we know is not a one-to-one mapping with objects. So the results you get will depend on which name we happened to see the object under first while traversing.

I think the case you are getting at is something like clean filters, where we might not have an object at all. In that case I would argue that a property of an object could never be satisfied (so neither "size > 500" nor "size <= 500" could match). Whether object properties are meaningful is in the eye of the code that is looking up the value. Or more generally, the set of properties to be matched is in the eye of the caller. So looking up a clean filter might want to define the size property based no the working tree size.

-Peff