Trac Database Schema: Common

Trac stores common authentication, caching, permission, session and system information in the database that is not specific to a certain module.

Table system

Table	Key
system	name

Columns

name

value

Stores some system properties.

Trac itself only uses this table for managing database upgrades. It initializes this table with the following data during installation or upgrades:

name	value
database_version	The (upgraded) DB version
initial_database_version	The DB version

These values can be accessed using env.get_version() and env.get_version(initial=True) where env is an instance of trac.env.Environment (e.g. self.env in a Component.)

(In earlier Trac versions, there were additional properties named repository_dir and youngest_rev. These are now part of the VcCache.)

See trac.env.Environment​

Table permission

Table	Key
permission	username, action

Columns

username

action

Stores TracPermissions (and TracFineGrainedPermissions).

If action is not all uppercase, it actually stores a permission group name. (username might store a permission group name in both cases.) This table should be used via the permission cache that can be used to check the permissions of the relevant user (both for performance and correctness reasons, e.g. other permission group providers etc. would be sidestepped otherwise.) That permission cache is for example available as req.perm for request handlers, or as formatter.perm for wiki macros.

During installation Trac initializes this table with some default permissions for the anonymous user and the authenticated group.

See trac.perm.DefaultPermissionStore​

Table auth_cookie

Table	Key
auth_cookie	cookie, ipnr, name

Columns	Type	Notes
cookie		Value of the cookie (32 random hex digits)
name		User name authenticated by this cookie
ipnr		IP address of the user
time	int	Last time of authentication

Stores authentication credentials of users. The trac_auth cookie identifies the entry of a authenticated user in this table.

See trac.web.auth.LoginModule​, TracDev/TracSession

Table session

Table	Key
session	sid, authenticated

Columns	Type	Notes
sid		Session ID
authenticated	int	1 for authenticated sessions, 0 for anonymous sessions
last_visit	int	Time of last visit of this session's user

Indexes

last_visit

authenticated

See trac.web.session​, TracDev/TracSession

Table session_attribute

Table	Key
session_attribute	sid, authenticated, name

Columns	Type	Notes
sid		Session ID
authenticated	int	1 for authenticated sessions, 0 for anonymous sessions
name		Name of some attribute stored for that session
value		Value of that attribute

This table can be managed using the Session object, which is usually available as req.session.

Trac itself uses session attributes to store various configuration settings, e.g.:

• Preferences
  • name, email
  • tz, dateinfo, lc_time
  • accesskeys
  • language
  • pygments_style
• Wiki editing settings
  • wiki_sidebyside
  • wiki_editrows
  • wiki_fullwidth
• Timeline settings
  • timeline.lastvisit, timeline.nextlastvisit
  • timeline.daysback
  • timeline.authors *timeline.filter.*
• Ticket settings
  • ticket_comments_order, ticket_comments_only
• Ticket Query settings
  • query_href
  • query_tickets
  • query_time
  • query_constraints
• Diff settings
  • diff_style
  • diff_contextlines

See trac.web.session​, TracDev/TracSession

Table cache

Table	Key
cache	id

Columns	Type	Notes
id	int	Identifies a certain property to be cached
generation	int	Current generation of this cached property
key		Usually the class-qualified name of the cached property

Use the CacheManager component e.g. via the cached_value decorator to cache values (in process or thread-local memory). This table is used to manage (e.g., correctly invalidate) these caches.

See trac.cache​, TracDev/CacheManager