Vault Cache .db file creation

Hi

I'm interested to understand a little more about the vault cahe and virtual vault .db files.

Specifically when is a new .db file created?

I undertand that if I were to rename a .db file to PST I can infact open the file in outlook and it appears to give me a folder structure of <year; month ; day> so does this mean that a new .db file is created every month and it will be appended to until the start of the following month when a new.db file will be created?

many thanks

Keir