I don't think this is a huge problem. Yes, long running queries might introduce lag. When this lag hits a threshold of your choosing, PGBackup (or any service t

I don't think this is a huge problem. Yes, long running queries might introduce lag. When this lag hits a threshold of your choosing, PGBackup (or any service that would offer it) would then gladly send out pager alerts. The same would happen if the WAL could not be retrieved in time (because wal storage full): PGBackup would start a new base_backup and send out pager alerts.