[Feature Request] To save metadata into google firestore database

[diyism]

Currently I'm using juicefs in google colab VM like this:

from google.colab import drive
drive.mount('/root/gdrive')
%cd /root/

!install /root/gdrive/MyDrive/ColabSingularity/juicefs /usr/local/bin

#!juicefs format --storage file --bucket /root/gdrive/MyDrive/ColabSingularity/gdrive_file_volume1 "sqlite3:///root/gdrive_file_volume1.db" volume1
!while true; do nohup cp /root/gdrive_file_volume1.db /root/gdrive/MyDrive/ColabSingularity/ > /dev/null 2>&1; sleep 10; done &
!juicefs mount -d "sqlite3:///root/gdrive/MyDrive/ColabSingularity/gdrive_file_volume1.db" ./gdrive_file_volume1

the object data successfully saved into my google drive in real time,
but the metadata only can be saved into my google drive every 10 seconds.

Since the google colab VM will be shutdown every 12 hours, there's a chance that my metadata sqlite file may be corrupted.
So could you support the google firestore database as juicefs metadata engine?

[davies]

@diyism Can you use managed SQL database other than sqlite?

Google firestore may not fit well as metadata engine, we don't have a plan to support it.