I would not get to know svn:externals if I haven't run into the this page. So, I setup my working folder. Then
mkdir lib/vendor
svn add --parents lib/vendor
svn ps svn:externals 'symfony http://svn.symfony-project.com/branches/1.4/' lib/vendor/
svn ci -m "add externals"
svn update
The "svn update" enlists the whole symfony folder and is pretty slow. I thought that would be single time pain. However, SVN will check external repository every time I typed "svn up". I have to use --ignore-externals to make "svn update" fast enough.
I'm wondering what's the benefits of svn:externals if it is so slow. I'd rather copy symfony to my own repository, which is surely a faster solution.