checkpoints are duplicated even while the system is idle

Hi,

While the system is idle, we skip duplicate checkpoints for some
reasons. But when wal_level is set to hot_standby, I found that
checkpoints are wrongly duplicated even while the system is idle.
The cause is that XLOG_RUNNING_XACTS WAL record always
follows CHECKPOINT one when wal_level is set to hot_standby.
So the subsequent checkpoint wrongly thinks that there is inserted
record (i.e., XLOG_RUNNING_XACTS record) since the start of the
last checkpoint, the system is not idle, and this checkpoint cannot
be skipped. Is this intentional behavior? Or a bug?

Regards,

-- 
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center