tracking binary files

tracking binary files

[bill lam]

I would like to use git to track some database files of sizes from 1MB
to 50MB.  I want to know does git compress them for storage or not.
If so, what will be the expected compression ratio.  Those files
normally compressed to 25% of original size using zip.

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Re: tracking binary files

[Jeff King]

On Thu, Feb 19, 2009 at 11:16:02AM +0800, bill lam wrote:

> I would like to use git to track some database files of sizes from 1MB
> to 50MB.  I want to know does git compress them for storage or not.

Yes, git will compress them via zlib.

> If so, what will be the expected compression ratio.  Those files
> normally compressed to 25% of original size using zip.

Then I would expect the same ratio, since I believe zip and zlib both
use the "deflate" algorithm.

Note, however, that git will also do delta compression between versions.
So storing N versions of a file should be no _worse_ than zipping and
keeping those N versions. But if the database files have small enough
changes from version to version (which depends on the database format,
and how much the on-disk structure changes for each update) then it will
compress even more.

-Peff