= Trac Database Schema =

The database schema is defined in [source:/trunk/trac/db_default.py trac.db_default], along with the initial contents of the database, and default configuration values. The schema includes the tables listed below.

|| '''Table Name''' || '''Purpose''' ||
|| {{{attachment}}} || Descriptions of attachments (files themselves are stored on disk). ||
|| {{{auth_cookie}}} || User login cookies. ||
|| {{{component}}} || Values that can be used in a ticket's "component" field.  The {{{owner}}} column is used as the default assignee for new tickets, if not overridden at the time of ticket submission. ||
|| {{{enum}}} || Maps integer IDs for issues' priorities, severities, etc. to human-readable names. ||
|| {{{milestone}}} || Project milestones. ||
|| {{{node_change}}} || For every changeset (as identified by the revision number), this table contains the nodes (i.e. files or directories) that have been added/modified/deleted. ||
|| {{{permission}}} || Username/action pairs describing who's allowed to do what. This table's contents also hold permission groups. ||
|| {{{report}}} || Stores the SQL to generate canned database reports. ||
|| {{{revision}}} || Changesets, containing the revision number, author, time, and log message.  The list of files and directories modified by a changeset can be found by joining with {{{node_change}}} on the {{{rev}}} column. ||
|| {{{session}}} || Information about user settings, including name, email, and diff options. ||
|| {{{system}}} || System information such as the database version. ||
|| {{{ticket}}} || Tickets. ||
|| {{{ticket_change}}} || Changes to tickets, on a field-by-field basis.  The field value {{{comment}}} is special: it associates a comment with a set of field changes. ||
|| {{{ticket_custom}}} || The values of custom ticket fields. ||
|| {{{version}}} || As in {{{component}}} and {{{milestone}}}, this holds the options of the drop-down {{{version}}} list on the ticket form. Every version can have a {{{time}}} set, although that is not presently used other than for ordering the list of versions in the UI. ||
|| {{{wiki}}} || Wiki pages (including old revisions). ||

----
See also: TracDev, TracDev/DatabaseUpgrades