Just a quick question. If I am fully synced, then I run Tools>Check Database, and try syncing again, should I click upload to ankiweb or download from ankiweb? I guess another way to ask this is checking the database is only looking at the ankiweb server and changing that, correct? So I would want to download from ankiweb after I check database every time, right?
You could think of Check Database as a maintenance tool, that allows you to check and optimize the state of the files of your collection, correcting errors that may have occurred.
For a more in depth description: Managing Files - Anki Manual
So, after using Tools>Check Database, if Anki prompts you for a full sync, in most cases the appropriate choice is to upload to AnkiWeb.
If you were to download instead, you would basically be reverting your collection to the state it was prior to using Check Database.
Yeah I read all the docs in the manual but it doesn’t say anywhere if check database is checking the database saved on the server or the database on device. According to your explanation, check database is optimizing the database saved on device, and doesn’t affect the database saved in the server until I sync and click Upload to Ankiweb. Thank you so much for your help!