* Feature of database session

* Make it configurable.

* Change the metrics process flow.
before: metrics entrance -> aggregate worker -> remote worker -> trans worker -> minute, hour, day, month persistence worker -> storage
after: metrics entrance -> aggregate worker -> remote worker -> minute persistence worker ->  trans worker -> hour, day, month persistence worker -> storage

* IntKeyLongValueHashMap instead of IntKeyLongValueArray.

* Make the OAP server can't startup.

* Finish

* Rename the method and fixed some test case issues.

* Rename field.

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