Below are some of the basic tables within a content database and a very high level diagram on some of the relationships between them.
Features
Table that holds information about all the activated features for each site collection or site.
Sites
Table that holds information about all the site collections for this content database.
Webs
Table that holds information about all the specific sites (webs) in each site collection.
UserInfo
Table that holds information about all the users for each site collection.
Groups
Table that holds information about all the SharePoint groups in each site collection.
Roles
Table that holds information about all the SharePoint roles (permission levels) for each site.
All Lists
Table that holds information about lists for each site.
GroupMembership
Table that holds information about all the SharePoint group members.
AllUserData
Table that holds information about all the list items for each list.
AllDocs
Table that holds information about all the documents (and all list items) for each document library and list.
RoleAssignment
Table that holds information about all the users or SharePoint groups that are assigned to roles.
Sched Subscriptions
Table that holds information about all the scheduled subscriptions (alerts) for each user.
ImmedSubscriptions
Table that holds information about all the immediate subscriptions (alerts) for each user.
NOTE: Never update any SharePoint database directly. Always use the SharePoint API (Object Model) for any updates.
For more info about the support for changes to the databases used by SharePoint, look at http://support.microsoft.com/kb/841057
Thank you for this diagram. I have been trying to identify which scanning station we use (they use unique login) is the heaviest load and the picture allows me to understand that AllUserData is the table to join with AllDocs to find which ID created the most documents.
are page layouts and masterpages also stored in content DB?