An item's metadata can be updated to include the current properties of the item. When you view an item's metadata in the details panel in the catalog view, metadata is retrieved from the item.
- If the item already has metadata, it is retrieved as is. Its content is not updated automatically for performance reasons.
- If the item does not have metadata, it is created for the item. During this process, the intrinsic properties of the item are recorded in its metadata.
The process of updating the properties recorded in the item's metadata with current information derived from the item's properties is known as synchronization. For example, when a feature class's metadata is synchronized, the current extent of the data, the number of features it contains, its spatial reference, and the fields in its attribute table are all recorded. The character ⇔ appears next to metadata elements that have been updated by the synchronization process to indicate the element's content represents a property of the item.
As you manage the item and its content, its properties change. If you later view or work with an item's metadata and find the properties recorded are out of date, you can synchronize its content. You must have permission to edit the item's metadata for synchronization to be successful.
- Open the catalog view.
- If the details panel is not open, on the View tab on the ribbon, in the Options group, click the Details Panel button
.The details panel appears.
- Browse to and select the item in the catalog view.
- On the Catalog tab on the ribbon, in the Metadata group, click Synchronize
.The metadata content is synchronized. The metadata display is updated to show the item's updated metadata content.
Some items support metadata but do not have any properties that can be synchronized, such as a geodatabase. For these items, only the date when the metadata was last updated will change to represent the current date and time when synchronization was attempted.
Editing synchronized metadata
When you edit an item's metadata, it is not recommended that you modify properties of the item that were added or updated by the synchronization process. In particular, this applies to the item's spatial reference, the names of fields in the attribute table, and so on.
Other aspects of the item are recorded in its metadata to provide a default value and are meant to be changed at a later time. For example, the item's name is recorded as the title. However, it is expected that a proper descriptive title will be provided for the item when it is ready to be published. When the item is available to the public, a descriptive title is important to distinguish this item from other similar works, especially when metadata is exported and published independent of the item itself.
The ArcGIS metadata editor works together with the synchronization process to keep the content of the item's metadata current. When a metadata element is added by the synchronization process it has an attribute indicating its content has been synchronized. Suppose a feature class is named parks. Each time synchronization occurs, the process only updates the element to contain the current property of the item if the synchronization attribute is present. If the item's title has not been modified in the editor and you rename the feature class city_parks, the item's title will be updated automatically the next time the metadata is synchronized to reflect this change.
When you edit an item's metadata, if you change the value of an element that was previously synchronized, the synchronization attribute is removed. This ensures that the next time the item's metadata content is updated, the information that was typed into the editor will not be lost. When your work on this feature class is finished and you edit the item's metadata, if you type a title such as Redlands Parks and save your changes, the synchronization attribute is removed. Any time in the future when the item's metadata is synchronized, the title will not be updated, even if the feature class is renamed.
Geoprocessing history and metadata
You can optionally choose to log geoprocessing operations in the item's metadata. When this option is enabled, each time you run a tool that modifies the item, an entry is added to the item's metadata. For example, when you create a feature class, this is accomplished by running a geoprocessing tool. Metadata will be created for the feature class by the process, and it will be updated to include the first entry in the geoprocessing history to indicate how the item was created.
You can choose to include geoprocessing operations in the item's official lineage in the ArcGIS metadata editor on the Geoprocessing History page. Each additional operation that defines the feature class's projection or adds and deletes fields in the attribute table will be similarly recorded in the item's metadata.
An organization may require an item's geoprocessing history to be maintained within its metadata, for example, to support legal questions where the provenance and processing history of the data are required to provide a response. An administrator can lock the setting and prevent you from changing it on the Geoprocessing tab on the Options dialog box.
There is also an option on the Metadata tab on the Options dialog box that determines whether an item's existing geoprocessing history can be deleted from its metadata. Administrators who require geoprocessing history to be recorded should also lock this setting to ensure the information remains available.
When datasets are created, used, and maintained over a long period of time, the recorded geoprocessing history can become very large. Metadata documents have been known to grow to 2 GB in size when years of an item's geoprocessing history are recorded; at this size, the performance of operations that analyze and maintain an item's data can be impacted. This is especially true for utility networks and parcel datasets that rely heavily on geoprocessing tools to evaluate and maintain their spatial data. For GIS professionals working with these datasets, administrators can override both of the above settings to prevent geoprocessing history from being recorded and to allow deleting this content.
When an item's geoprocessing history negatively impacts the performance of the geodatabase as a whole, it is advisable to delete this content. An option is available for the deleteContent method in the arcpy.metadata Python module that allows you to delete an item's geoprocessing history. This method will not succeed if the Allow geoprocessing history to be deleted from metadata option is unchecked on the Options dialog box. The option to delete geoprocessing history from an item's metadata is not yet available in the ArcGIS metadata editor.
Other operations that update metadata
In addition to metadata editing, metadata synchronization, and the recording of geoprocessing history, other ArcGIS software operations may update an item's metadata. For example, a few items record properties of the data directly within their metadata, and are updated as the data is modified.