[Yum-devel] Re: [Linux at Duke Project Wiki] Update of "YumTodo" by JeremyKatz

[James Bowes]

On Tue, 22 May 2007 18:54:25 -0000, wiki-noreply at linux.duke.edu wrote:
> ------------------------------------------------------------------------------
>      * changelog?
>      * tsflags?
>    * yum list vendors
> +  * how can we cut down on the metadata download?  presto will help cut down on payload downloads, but then the 10 megs of metadata (3 megs for just primary) gets to be excessive

I would love to get this solved in time for F8. My thoughts so far have
been to craft up some delta metadata format, where for each of
primary/filelists/other you would have a file like so:

<removed>
  <pkg id="CHECKSUM" />
  <pkg id="OTHER CHECKSUM" />
</removed>
<added>
 <pkg>
   FULL PACKAGE INFO
 </pkg>
</added>

We could go further and do an 'updated' section, which could give an id
of an existing package, and any changes that the new one has (say, just
the release number and change log entry).

These deltamd files could be referenced by some kind of index file,
which would allow the client to figure out which delta sets its
missing, and grab them. The index would specify file size, so the
client can figure out if its worth downloading all the deltas it needs,
or just grab the thing fresh.

So the base repomd files/sqlite files would be whatever is the newest,
and a new set of primary/other/filelists deltas would get generated
each time the repomd files are updated. Old deltas can get cleared out
when the size of all the deltas exceeds the size of the whole files
plus some constant, so that out of date clients don't get messed up.

Let me know if any of this makes sense ;)

-James
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