Are revlog diff calculated as "text" ALWAYS?

[Jesus Cea]

On 13/05/14 21:21, Matt Mackall wrote:
> That's a rather unusual binary file, no? Indeed, it will completely
> defeat our delta algorithm.

This file in explicitly build to show the problem and get your attention.

> But a binary that contains any of the following will have plenty of
> linefeed bytes (0x0a):
> 
> - compressed data of any sort
> - raw binary data with non-contrived distributions
> - machine code
> - embedded text
> 
> ..so if you can find a real-world 200k file that doesn't have enough
> 0x0a bytes in it to be digestible, I'll be amazed.

a) Take an odt (OpenDocument/OpenOffice/LibreOffice).

b) Depack the document with ZIP. It is just a ZIP file. Really.

c) Check "content.xml".

It is a HUGE document with no or very few linefeeds on it.

I detected this problem when using hg-zipdoc extension
<http://mercurial.selenic.com/wiki/ZipdocExtension>, specifically
designed to help with ODT files (any ZIP file, actually), and I was
getting far worse deltas that expected. Exploring this fact I discovered
this issue.

So yes, the file I proposed is specifically engineered to be patological
and not represents a real life example. But yes, there are real life
examples that exhibit the same problem. Easy to find and painful to manage.

-- 
Jesús Cea Avión                         _/_/      _/_/_/        _/_/_/
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