Updateing indexed items works weird

I have a folder A. I don’t want to store any file in DEVONthink Pro, so I just use DT to index it. But after deleting a file from folder A, it keeps itself in DT database ( in some “file.noindex”).
How can I just keep database in sync with folder A ? I suppose indexing a folder instead of storing the folder in database should be in sync also.
Thanks in advance.

If you found the file in a subfolder of files.noindex then somewhere along the line you either imported it or you made a copy of an indexed file and moved it into the database. Otherwise, indexed files are not copied into the database.

I replicate to Mobile Sync. Is that the cause?
I want to sync with my iPad.

That means I should not use Mobile Sync?

Not enough information provided to answer that.

If you have an indexed document, Sync it to an iPhone or iPad with DTTG, edit or annotate it using some program on the iPad or iPhone, and then sync it back – in some cases DEVONthink will make a separate copy that contains the edits and annotations. The second copy will be stored in the database package (i.e., in files.noindex). (BTW, please never delete files manually from files.noindex.)

I don’t edit files in DTTG. I sync to iPad to read the files.
Here’s how I use DT: I use DT to index folder A on my Macbook. As I replicate the folder to Mobile Sync, every time I open DT it just reindex and Mobile Sync section updates too. Then I open DTTG on iPad and sync it. Files in folder A will be deleted or edit on Macbook, but not on iPad.
So I’m puzzled there’re files in file.noindex. The files in file.noindex are those I had deleted in folder A. Are there some scripts or methods to delete them and keep my database the same with folder A? (BTW I don’t want to reindex folder A for it’s several GBs and indexing takes a whole night)

Unless there’s a missing step in the scenario, then the imports should not be happening. Looks like Support is needed.

Thanks for your advise. I’ve create a support ticket.