Creating replicas(ArcInfo and ArcEditor only)
Release 9.3 Last modified April 2, 2009	Print all topics in : "Managing Distributed Data"

About creating replicas

You can replicate data from a geodatabase using the Create Replica wizard in ArcMap. Using this application, you can define what data should be replicated and which geodatabase the data will be replicated in. The wizard supports a range of default and advanced replication options.

If more than one workspace is present in the map document, you will have to choose which workspace to create the replica from. The Create Replica wizard supports both local and remote geodatabases. Remote geodatabases are accessed through geodata services published on ArcGIS Server.

You have a choice of which type of replica to create: checkout/check-in, one-way or two-way.

Each replica name must be unique to the user creating it. User1 and user2 could each create a replica called MyReplica, but neither could create multiple replicas with that name.

In checkout/check-in replication, a new version is created with the name of the replica. The combination of user name and replica name must be unique when creating versions.

The Reuse schema option, available for checkout/check-in replication only, allows you to reuse a geodatabase that contains the schema of the data you want to replicate. This reduces the amount of time required to replicate the data.

Before creating a replica, review the Preparing data for replication topic to understand data requirements and how to specify what gets replicated.

NOTE: Metadata for the feature classes and tables you choose to replicate is copied during the replica creation process. However, changes to the metadata are not applied during replica synchronization.

Default behavior
The default behavior for each replica will be the following:

• To include all the data you have permissions to edit, visible and invisible, in the active document for the chosen geodatabase.
  
• To maintain any selections and definition queries applied to that data.
  
• To restrict the spatial extent of the replica to the current view extent of the document or the boundary of a selected graphic.
  
• To include any directly related objects.
  
• To expand the list of layers and tables to replicate to include dependent datasets. For example, all feature classes in a geometric network will be included if just one feature class in the geometric network is selected.
  
• If there are several layers representing one feature class in the document, only the top layer in the table of contents is used in the replica.
  

Advanced options
The advanced replication options allow you to customize the replica.

If you are creating a one-way replica, a panel in the advanced options offers the choice between full or simple replica models. The default is the full model where complex data types are created on the child and versioned. This data must remain versioned. If you choose the simple model, the data is created on the child as simple and is not registered as versioned if the child is hosted by ArcSDE. The data can be registered as versioned later on or left as unversioned.

The advanced options will initially reflect the current replica defaults and the expanded list of all the datasets that will be included in this replica.

The extent of the replica area may be determined by one of the following:

NOTE: If you are creating a checkout/check-in replica and schema-only was selected previously, this section is grayed out.

• The current view extent (the default)
  
• The full extent of the data
  
• The boundary of a currently selected graphic
  
• User-defined coordinates
  

The options in the grid determine how many records from each layer or table will be replicated. In addition to excluding layers and tables from the list of data to replicate, you may also override the defaults for individual layers and tables. For example, if a selection set exists for a layer, you may choose to disregard that selection for this replica. By default, all layers will be filtered by geometry, selection, definition query, or a combination of these.

The default is to replicate all features in a layer. If you are interested in replicating schema only, you can choose that option under the Check Out column.

For tables, if no other filters have been applied (for example, a selection), the default filter is Schema Only; only the schema for the table will be replicated.

If you wish to exclude a geometric network or topology from a replica, you must exclude all the participating layers; including just one layer will result in the whole network or topology being replicated.

By default, related data is replicated. If you would like to turn off relationship class processing, uncheck the Replicate related data check box.

For two-way replicas, there is an additional advanced option to select whether the initial data sender is the child replica or the parent replica. This setting is only important in systems where you plan to work in a disconnected environment.

Using the keywords panel in the wizard allows you to specify the DBMS storage configuration keywords for each object involved in the replication. By default, the defaults keyword is specified.

The final panel includes some postcreation replication options:

• No further action (the default)—The current document will not be modified and no new documents created.
  
• Change the layers and tables to point to the replicated data—The current ArcMap document will be modified to point to the data in the relative replica geodatabase, preserving all symbology.
  
• Save a copy of this map document with the layers and tables pointing at the replicated data—A new ArcMap document referencing the data in the relative replica geodatabase, again with symbology preserved, will be created.
  

By clicking the Sumary button, you can review the properties you specified for creating the replica in the Create Replica Summary dialog box.

To see an example of creating and synchronizing replicas in a connected environment, click here.

How to

Create a replica

1. To activate the Create Replica wizard in ArcMap, click the Create Replica button on the Distributed Geodatabase toolbar.
   
2. If the current ArcMap document includes data from more than one ArcSDE geodatabase, you will be prompted to choose which ArcSDE geodatabase you want to work with. The Create Replica wizard supports both local and remote geodatabases. Remote geodatabases are accessed in ArcMap through map services that have the geodata access capability enabled.
   
3. The first panel gives you a choice of which type of replica to create: checkout, one-way, or two-way.
   
4. On the next panel, you have the choice of replicating data or registering existing data only. The option to register existing data only allows you to create a replica between two geodatabases containing the same data.
   
To learn more about creating replicas with the option to register existing data, consult the section Create a replica with the option to register with existing data below.


5. If you are creating a checkout replica, the second panel of options also offers a choice of replicating Schema Only. If you require only the schema, this option can be used instead of manually setting the filters for each feature class and table to schema only. The option is grayed out for one- and two-way replicas.
   
6. You have the choice of replicating to a geodatabase or an XML workspace document. If you choose the XML option, you can later import the workspace into another geodatabase using the workspace importer. Replicating data in a disconnected environment is only possible if you replicate your data to an XML workspace document. To learn more about creating replicas in a disconnected system, read the How to section below these steps.
   
7. Enter the name of, or click the Browse button to navigate to, a personal geodatabase, XML document, or ArcSDE connection to which you want to replicate data. If the XML file does not already exist, it will be created. For two-way replicas, the geodatabase that you replicate the data to must be an ArcSDE geodatabase. For checkout/check-in and one-way replicas, this can be either an ArcSDE, personal, or file geodatabase. You can browse for local and remote geodatabases.
   
8. If you want to reuse schema in an existing geodatabase, check Re-use schema. This option is also only available for checkout/check-in replicas. To learn more about reusing schema to create replicas, read the How to section below these steps.
   
9. A default name for the new replica is provided. The name of each replica must be unique to the user creating the replica.
   
10. If you want to override the replication defaults, check Show advanced options.
    
11. Click Next to proceed. If you are not making any changes to the default options, skip to step 18.
    
12. For one-way replication, the first panel in the Advanced Create Replica Options offers the choice between a full or simple model. The default is the full model where complex data types are created on the child that is versioned and must remain versioned. If you choose the simple model, the data is created on the child as simple and is not versioned. Click Next.
    
13. To modify the spatial extent of the replica, click the appropriate extent option.
    
14. To exclude individual layers or tables from the replica, uncheck the check box associated with that layer or table.
    
15. Each entry in the Check Out column is a combo box of options. The options always include All Features and Schema Only. If a particular layer or table has a selection set or definition query defined, the options may also include Selected Features Only, All Features in Def. Query, and Selected Features in Def. Query. Select All Features and uncheck the Use Spatial Extent box if you don't want to apply any data filters.
    
16. Uncheck the Related Data check box if you do not want to replicate any related data. Click Next.
    
17. If you choose to include related data and are replicating relationship classes, a panel is displayed that allows you to set how relationship classes are processed. This includes the direction or processing, which is forward by default, and the ability to turn off processing for individual relationship classes. Click Next.
    
18. For two-way replication, there is an additional panel in the Advanced Create Replica Options dialog box that lets you choose whether the parent or child will be the initial data sender. This option is only important in disconnected systems.
    
19. The next dialog box allows you to specify creation keywords for the replica. You have the option to choose the defaults or specify an appropriate configuration keyword for each object involved in the replica.
    
20. The Post Create Replica Options dialog box gives you three options for what you want to do once the replication has been completed.
    


• Take no further action—The default option where the replica will be created with the ArcMap document showing the original data.
  
• Change the layers and tables to point to the replicated data—The current ArcMap document will be modified to point to the data in the replica geodatabase, preserving all symbology.
  
• Save a copy of this map document with the layers and tables pointing at the replicated data—A new ArcMap document referencing the data in the replica geodatabase, again with symbology preserved, will be created.
  



21. Click Summary to review the parameters for the current replica.
    
22. Click Finish to start replicating the data. The status of the replication operation will be monitored in a progress dialog box.
    

Learn more about creating replicas.

Create a replica with the option to register with existing data

This option is available for users with large datasets or those that have identical data in two different geodatabases. The replica creation process of copying data to another geodatabase and registering it can be time consuming on large datasets. If you have a fast method of transferring data between databases, such as a database dump, it may be easier to copy data from one database to another and then go through the Create Replica wizard with the option to register with existing data. This will create the replica versions needed to synchronize changes between the geodatabases, but will not go through the lengthy process of copying data since it already exists in both locations.

Some tips on using this method follow:

• You must make sure to add global IDs to the data before you copy it to the other geodatabase. If using functionality within ArcGIS to copy the data, make sure to use either copy and paste, data extraction, or XML workspace export and import.
  
• You must be connected as the owner of the data on the target geodatabase when creating the replica.
  
• Whatever filters are applied during the replica creation process also get applied to the data in the relative geodatabase.
  
• This option also works in disconnected environments.
  

Create a replica in a disconnected environment

Creating replicas in a disconnected environment is slightly more involved than in a connected environment.
There are several things to remember when creating replicas in a disconnected environment:

• You must choose to create the replica to an XML document in the Create Replica wizard.
  
• After the replica is created, it needs to be sent to the relative geodatabase by some transfer medium such as CD or DVD.
  
• The relative geodatabase then needs to import the XML document to finalize the create replica process. This can be done using the Import XML workspace command with a connection relative geodatabase.
  

Create a replica by re-using schema

This option is available for checkout/check-in replicas only and can only be performed when replicating to file or personal geodatabases. The purpose is to create a replica by browsing to a schema and using it as a template.

The most efficient way to utilize this method is to use the Extract Data wizard on the dataset whose schema you want to reuse before going through the Create Replica wizard. In the Extract Data wizard, choose to extract schema only in order to create a template to use. This will create a copy of the dataset's schema but will contain none of its content. When creating the replica in the Create Replica wizard, browse to this empty schema when choosing which geodatabase/XML to check out to (step 8 of "How to create a replica"). You must then select the Re-use schema option.

The reason for doing this is that the Re-use schema option in the Create Replica wizard will first delete any datasets currently in the schema it is to reuse and then repopulate it with the data specified for replication. This will not only run the risk of deleting important data but also takes longer than browsing to an empty schema and reusing it to create the replica.

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