Introduction to distributed data—ArcGIS AllSource

The distribution of data involves creating copies of data for dissemination between two or more geodatabases or services.

Data distribution improves data availability and alleviates issues such as server contention and slow network access to a central server. This can help an organization balance the load placed on a geodatabase between users who perform edits and those who require access for read-only operations.

Distributed data is also useful when you need to perform edits in the field, disconnecting from the network entirely for an indefinite amount of time.

There are several ways to distribute data in your organization.

Copy and paste

Some organizations achieve a level of data distribution by saving copies of their geodatabases and sending them to other offices. These offices can then work on the data, make edits, and send a copy of their updated geodatabase back to the main office. Here, edits are compared and coordinated to ensure that the data at the two offices remains in sync. This solution can work with careful communication; however, there are many opportunities for updates to be lost, and it can be difficult to keep the two geodatabases in sync.

Geodatabase replication

Geodatabase replication is a data distribution method in which data is distributed across two or more geodatabases by creating a replica of only a part of or an entire dataset.

When a dataset is replicated, a replica pair is created; one replica resides in the source geodatabase, and a related replica is distributed to a different geodatabase. Any changes made to these replicas in their respective geodatabases can then be synchronized so that the data in one replica matches the data in the relative replica. The term relative replica refers to the other replica in a replica pair. Each replicated geodatabase can work independently, and all changes can still be synchronized.

Geodatabase replication is built on top of traditional versioning and uses versioning functionality to synchronize data in most scenarios.

Geodatabase replication provides multiple options to meet your requirements, including the following:

Use local geodatabase connections, which allows you to access a geodatabase through a local area network (LAN).
Use a geodata service, which allows you to access the geodatabase through the internet.
Because it is implemented at the geodatabase level, the respective database used by each relative replica can differ. For example, one replica geodatabase can be in a SQL Server database, while the other is in an Oracle database.
There are different types of replication available to implement different distributed data workflows. See Geodatabase replication types for a list and description of each supported replication type.
You can use geodatabase replication when connected to your network and in disconnected environments. See Connected and disconnected replication for more information.

For a list of supported datasets and limitations of geodatabase replication in ArcGIS AllSource, see Replication and geodatabase compatibility.

To get started with geodatabase replication, see how to prepare data for replication.

Take a map offline with feature service sync capability

The sync capability available for ArcGIS Server feature services and hosted feature layers allows you to take feature layers offline in a web map that is configured for offline use. When the data is taken offline, the layers reference a local copy of the data. This allows you to make edits and complete your work without the requirement to be connected to the network. Once network availability is restored, you can upload your local edits.

When you enable sync on a feature service (feature layer), you can also use it in a distributed collaboration.

Before you publish an ArcGIS Server feature service to be used offline, you must configure the data to meet offline requirements.

Feature service replicas

Feature service replicas provide the mechanism that allows you to synchronize offline feature layers with the source data. The feature service replica receives edits made offline that are subsequently synchronized to the source feature layer. During synchronization, the feature service replica also receives the edits made in the source feature layer and makes them available to the feature layer that was taken offline.

When you take ArcGIS Server feature service data offline, a feature service replica is always created.

Tip:

Depending on the data present in the feature service and the options used when you publish the service, a replica version may also be created and associated with the feature service replica. To learn more about scenarios when a replica version is created, see Prepare data for use in offline feature services.

Feature service sync vs. geodatabase replication

Taking a map offline using the feature service sync capability copies data from a web service (feature service) to a local mobile geodatabase, whereas geodatabase replication uses enterprise and file geodatabases. The key benefit of taking a map offline using feature service sync capabilities is the ability to synchronize data multiple times versus the checkout geodatabase replica type, where changes can be synchronized only once.

DBMS replication

Database management systems have their own replication mechanisms, which can be used to make copies of, and synchronize geodatabase data.

DBMS replication refers to the built-in replication mechanisms provided by the DBMS in which the geodatabase is stored. DBMS replication is not geodatabase aware. This means that geodatabase constructs, such as relationship classes and utility networks, are not known by the DBMS. However, DBMS replication can still be configured to work in a limited way with geodatabase data.

DBMS replication vs. geodatabase replication

The following facts compare geodatabase replication and DBMS replication:

Geodatabase replication synchronizes changes from specific enterprise geodatabase versions. DBMS replication, when used with an enterprise geodatabase, applies changes across all versions in the geodatabase.
Geodatabase replication supports some advanced geodatabase objects such as topologies, relationships, and feature-linked annotation. DBMS replication does not properly replicate advanced geodatabase objects.
Geodatabase replication allows you to replicate portions of your geodatabase. DBMS replication used with a geodatabase requires that you replicate the entire database.
Geodatabase replication allows two-way replication. DBMS two-way replication is not supported against a geodatabase.

Distributed collaboration

Distributed collaboration extends the reach of your GIS content by seamlessly sharing maps, apps, layers, and more with other organizations. Distributed collaboration (or simply collaboration) is based on a foundation of trust between participating organizations and is motivated by common goals and initiatives that support data access and sharing. Collaborations can be useful for many workflows, including exposing ArcGIS Enterprise content to the public through ArcGIS Online, making data visible across different departments in an organization, and managing field data collections. There is no single pattern for collaboration, so you can implement it in the way that best suits your needs.

Distributed collaboration supports referencing or copying feature services (feature layers). If you choose to copy feature services, you will first need to enable sync. Learn more about preparing data for collaboration in Prepare feature services for offline use and About sharing feature layer and view data as copies.

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