You cannot Sync part of a database in DEVONthink To Go. In DEVONthink To Go, you have two options for syncing an entire database: Contents and metadata or Metadata only.
Metadata only (which we call a “shallow Sync”) is only available with an in-app purchase of the Pro Pack (see DEVONthink To Go’s Settings > Manage). You set can Download Files to Always (a full Sync) or On demand (a shallow Sync) for a sync location, an entire database, or individual groups in a database.
Alternately, some people have chosen to create smaller databases, just for syncing.
If you have purchased the Pro Pack and want to use a shallow sync, you need to set the sync location to Download Files: On demand.
In DEVONthink To Go’s Settings > Sync : Edit Locations, press the Edit link and touch the Sync location. You can set the Download Files option to On demand here. You can then change the option at the database level in the Info popup in the bottom Toolbar when you’re in the database.
NOTE: There is a file retention setting to consider too. Check out Settings > Keep All and move the slider up or down as desired.