When I do a
yum install or a
yum update, sometimes I get this
Loaded plugins: presto, refresh-packagekit
telling me that the packages are being updated.
What is presto?
Presto makes yum download only the delta. The changes. It downloads them and apply them on the existing data, thus it saves a lot of bandwidth. (You pay with Disk IO and CPU load instead.)
It is a really good thing for developing countries, people with mobile internet and so on.
ps.: OpenSUSE been using this for a long time. If I remember clearly they were the first RPM based delta users, but fixme, I'm not sure about this. (openSUSE downloads delta, apply, install package. On Fedora: Download all delta, apply them, install them all.)
It adds support for delta-RPMs which use a delta-transfer algorithm to save time downloading. Basically, presto won't download the entire package, only the changes since the last version.
Presto is a plugin which enables Delta RPM support in yum. Basically, deltaRPM creates a new RPM based on the diffs of the new and previous version - saving on bandwidth and time required to download, since only the "changed" bits will be downloaded, instead of the full monolithic package.