You can examine historical information in archive-enabled classes by connecting to a historical moment. A historical moment is a specific moment in time that is either the current database's time (the default historical marker), a predefined historical marker, or a database date and time that you specify.
Date and time
When working with archived information, it's important to understand that the date and time recorded in the gdb_from_date and the gdb_to_date fields of the archive reflect the date and time a transaction took place—when a feature was added, edited, or removed from the feature class. This date and time is received from the server operating system where the database is running. This affects how you access and query the archive.
If you're working in a time zone different than the database, queries against a moment in time must reflect the time of the database's server, not the time on the client operating system. For example, if you perform an edit at 9:05 a.m. (PST), but the DBMS resides in New York, the transaction time recorded for this edit is 12:05 p.m. (EST). Subsequently, if you were to query the historical version for 9:05 a.m., you would no longer see the edit, because at 9:05 a.m. on the database's server, that feature had not been created. To see the newly added feature, you would need to query the geodatabase for 12:05 p.m.
Note:
When you connect to a historical moment, if you specify a date and time prior to the moment that archiving was enabled, no data will be accessible. Archived data is only accessible from the moment you enable archiving forward. For example, if you enable archiving on 2/1/10, then change to a historical moment specifying the date 1/31/10, no data will appear.
Historical markers
A historical marker is a named moment in time that you create. Creating historical markers makes it easier for you to connect to specific moments and also to navigate between moments for viewing and analysis. You can create, edit, delete, and connect to historical markers in the History pane.
These are some tips on historical markers:
- All users have privileges to create, modify, and delete historical markers.
- The default historical marker is a reserved name and cannot be deleted or renamed.
- If you delete or rename a historical marker that is currently in use in another ArcGIS AllSource session, you'll lose your data sources in the second session.
Default historical marker
Connecting to the default historical marker displays the current representation of the archive classes, which is equivalent to the class representations in the transactional default version.
Note:
Connecting through the default historical marker allows a read-only connection, which can consume fewer database resources than working with the equivalent versioned class. The archive class does not rely on the information stored in the delta tables or the geodatabase versioning system tables, meaning that querying the archive class for all records that are currently active (gdb_to_date of 12/31/9999) can often be faster than querying the default transactional version.
Connect to a historical moment in the History pane
To access the History pane, click the database icon near the top of the Contents pane to change the pane to list by data source. Next, select a data source in the list. If the data source has one or more versioned or archiving-enabled classes, the Versioning tab will become available. In the Archiving section of the tab, there is a Historical Moments button. Clicking this button will open the History pane.
The History pane has a drop-down menu containing the data sources from the current map and three options for connecting to a historical moment. You can provide a specific date and time you want to connect to, select a predefined historical moment, or return to the current time.
Note:
The Return to current time option is unavailable unless you're connected to a historical moment.
Tip:
If you check the Auto Apply check box at the bottom of the History pane, whenever you enter a specific date and time on the dialog box, or select a historical moment, the map will automatically refresh and display a read-only view of the data for the moment in time you specified.
Connect to a specific date and time
To connect to a specific moment in time, click the Specific Date and Time button in the History pane and type the date and time you want to access.
You can also click the calendar button to bring up a calendar of dates and a clock. Choose the date you want by clicking it in the calendar, and choose a specific time by either typing it in the time dialog box or using the arrows next to the dialog box to increase or decrease the time. Click outside of the calendar to return to the History pane and submit the choices you've selected from the calendar.
When you click Apply at the bottom of the History pane, the map will refresh and display a read-only view of the data for the moment in time you specified.
Connect using a historical marker
To connect to a historical moment, click the Historical Moment button in the History pane. This will enable the grid containing the default historical marker and any other historical markers you previously created. Selecting one of the markers and clicking Apply at the bottom of the History pane will refresh the map and display a read-only view of the data for the moment in time specified in the Date column for that historical marker.
You can filter the grid by a historical marker's name using the Name text box above the grid. Start typing in the text box, and the grid will display only historical markers that match the text you've typed in the Name text box so far.
You can also filter the grid by typing in the Start and End text boxes above the grid. To see all of the historical markers created after a certain date, type the date in the Start text box. To see all of the historical markers created up to a certain date, type the date in the End text box.
Return to the current time
If you're currently connected to a historical moment, you can return to the current time by clicking the Return to Current Time button near the bottom of the History pane and clicking Apply. When you're connected to a historical moment, you're in a read-only view of the data for that specific date and time. By returning to the current time, you can edit and update features in the map again.
Connect to a historical moment from the database connection
You can also use the Geodatabase Connection Properties tab in the database connection dialog box to connect to a historical moment from a database connection.
To open the Geodatabase Connection Properties, right-click a database connection in the Catalog pane or catalog view and click Geodatabase Connection Properties.
From the dialog box, you can connect to a historical moment by choosing any of the following options under the Historical Moment section:
- Historical Marker—Choosing this enables the drop-down list of available historical markers. Choose a historical marker from the list to connect to the date and time it represents.
- Specific Date and Time—You can provide the exact date and time that you want to connect to or use the calendar to browse to a specific date and time.
- Current Date and Time—Choosing this will connect you to the current date and time. Unlike connecting to the current time in the History pane, the data will be read-only and edits can't be made.
Create, modify, and delete historical markers
To create markers or make edits to existing markers, click the Historical Moment button in the History pane. This activates the grid containing the list of historical markers. At the bottom of the grid is an Edit Markers button. Clicking this will put the grid in an edit mode allowing you to create, delete, or modify the properties of historical markers.
After you're done creating, updating, and deleting historical markers, click the Save button to save the edits you've made. If you're not interested in saving the edits, click Discard to discard them.
Create a historical marker
To create a marker, put the Historical Moment grid in edit mode by clicking the Edit Markers button. At the bottom of the grid there is a row that says Click here to add a new marker. Clicking in that row will add a new marker and set the date and time to the current date and time. Click in the Name column and enter a new name for the historical marker. To specify a different date, click in the Date column and enter one. Clicking the down arrow will bring up a calendar and clock that you can also use to enter a specific date for the historical marker.
Edit properties of a historical marker
To edit the properties of an existing historical marker, put the Historical Moment grid in edit mode by clicking the Edit Markers button. You can change the name of a historical marker by double-clicking its name and typing a new one. Similarly, you can change the date and time for any given historical marker by double-clicking its date and entering a new one. Clicking the down arrow will bring up a calendar and clock that you can also use to choose a specific date for the historical marker.
Delete a historical marker
To delete a historical marker, put the Historical Moment grid in edit mode by clicking the Edit Markers button. Then select the historical marker you want to delete and either press the Delete key on the keyboard, or right-click and click Delete.