Why the space occupied by virtuoso.db gradually becomes larger?

[JBoRu]

Hi,
Excuse me. I have downloaded your provided virtuoso.db and configured the environment. After successfully running the virtuoso.py, I use the SPARQLWrapper to query the freebase. And I find, after some query operation, the desk space occupied by the virtuoso.db file has increased from ~50G (the initial downloaded file) to ~140G. Using the command ll, I find the latest change time for this file is updated for the latest time, which means it is modified along with the using process. But I don't know why this happened? Is there some query cache? And how should I solve this problem? I hope you can help me.
I am looking forward to your reply.

Thanks！
jinhao.

[JBoRu]

Sorry, I make a stupid error, and I have solved this problem.