Right now BACKUP omit similar files, and will not allow to use this
backup as a regular table, and usually those similar files are quite
small (i.e. columns.txt).
So by using `BACKUP TO S3() deduplicate_files=0` you will be possible to
use `ATTACH TABLE` directly from S3.
P.S. right now it is possible only for the table with one part, since,
usually, there is nothing to deduplicate (if the columns are different).
v2: Add deduplicate_files into metadata
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
