We'd like to allow a user to do a partial, or selective, restore/restart from a full backup. That is, the WiredTiger.backup file contains all the metadata for the database, but the user would like to restart on a subset.

Currently WiredTIger will create new, empty files for any files that are missing. This happens in meta_turtle.c:metadata_load_bulk where any missing file is assumed to be an in-progress bulk-load that was interrupted.

We need a new configuration setting, perhaps backup_load=all|partial. When set to partial the call to create WiredTiger.wt from WiredTiger.backup will remove any entries for tables/files that do not exist. This should be done in meta_turtle.c:metadata_load_hot_backup. Care needs to be taken such that if name.wt does not exist on disk then we remove all the entries for that table file:name.wt,table:name,colgroup:name.