The svn_repos_node_location_segments() needs to quickly identify the revision in
which a line of history came into being. (And I'm sure there are plenty of
other applications for this knowledge). For the BDB backend, an index table
mapping NODE-IDs to the first NODE-REV-ID in the line of history would be a
super-cheap way to get at this information:
first_node_rev_id = svn_fs_base__node_origin_id(node_id); ## new
txn_id = svn_fs_base__id_txn_id(first_node_rev_id);
revision = svn_fs_base__txn_get_revision(txn_id);
The great thing is that for BDB as well, this table could be lazily populated
like any ol' cache.
Major