No, not global. Each office only really need access to their own documents, there are over 2,000 offices though. It does need to be high speed and yes cost is a factor.
If you are willing to try out some beta software, give https://didgets.com/ a look. You can load in hundreds of millions of documents or other kinds of files and put meta-data tags on each of them. Queries for individual documents or sets of them execute with sub-second speeds. The software is in beta and available for free download.
Currently working on the indexing feature to index the contents of the files too.
Currently working on the indexing feature to index the contents of the files too.