Forward full view to a downstream

[Kevin B]

Hello,

My customer wants me to announce a full IPv4 table via BGP to him, but 
we don't use it on the BGP node where that customer is peered. We 
receive the default from our BGP upstream, but can actually ask for and 
receive a full view as well, but only for a purpose of forwarding it to 
the customer.

What would be a scheme to receive a full-table from a BGP upstream and 
forward it to a BGP downstream, without importing it to our own routing 
table?

I am not very experienced with Bird, but some guys on Freenode 
##networking have suggested using a pipe, can someone help me on this 
please?