block missing in prometheus tsdb data directory

[陈卢鑫]

I checked the prometheus tsdb data folder, the most recent block minTime and maxTime is  1640736000008 and 1640757600000 (which is 2021-12-29 14:00:00 Beijing time).

But the oldest file in chunks_head and wal directory is about 12-29 18:00 Beijing time.

I am confused why the time series between 14:-00 and 18:00 are not written to disk as blocks. It seems they are in memory, since I can query them out in prometheus UI.

I have checked the log and could not find any related logs. Is there anything wrong here? Or did I misunderstand something ?