Even if it has been removed from the DB, Values does not disappear from the ValueCache.

There is a possibility of trigger evaluation. (Trigger like .last(#2))

Steps to reproduce :
1. Create a trigger.

({HOST:icmpping[127.0.0.1,,,100,].last(#3)}=0 & {HOST:icmpping[127.0.0.1,,,100,].last(0)}=1)

2. Change item and receive 1 to 0.

icmpping[127.0.0.1,,,100,] -> icmpping[128.0.0.1,,,100,]

3. Change item and receive 1.
Then, Click a 'Clear history and trends' and remove all history datas
4. Next first time check, 'last(#3)' will evaluated.

If set to ValueCacheSize=0, It does not reproduce.