Hourly backup using pg_basebackup

Hi all,

We have a python script called by cron on an hourly basis to back up our production database. Currently, the script invokes pg_dump and takes more than hour to complete. Hence the
script looks to see if it's already running and exits if so. I want to change the script so it uses pg_basebackup instead since that's so much faster.

My problem is, however, that while I'd like to just have it build a tarball, maybe compressed, I can't use a "-X s" option for the wal segments. I think I understand why I can't
use the streaming option with a "-Ft" specified. I'm just concerned about the docs saying that the backup may have problems with fetch as a wal segment may have expired. Manually
testing is showing that the Db needs about 11 minutes to backup with pg_basebackup, and our wal_keep_segments setting is 6. This said, an hour's worth of wal segments should be
available, but the six that were there at the beginning of the backup are not the same six there at the end. I don't think this is really a problem, but I'd like to get it
confirmed. Wouldn't the backup actually have to take more than hour for this to be an issue?

Thanks in advance,
Jay