Comparing Remote Data Access and Merge Replication

Deciding between using Remote Data Access (RDA) or using replication in your Microsoft SQL Server 2005 Compact Edition (SQL Server Compact Edition) application depends on the purpose, function, scale, and requirements of your smart device application. Each connectivity data solution has different advantages and disadvantages.

Both RDA and replication are good for wireless transports. Compression is used to reduce the size of transmitted data. You can use encryption to safeguard sensitive user data during transmission.

Feature Comparison

Feature	Replication	RDA
Exchange of tracked data changes	Replicates changes to and from server and client Column-level Tracking – reduces the amount of data transferred, by only transferring changed column data Row-level Tracking – whole row is transferred	Pushes changes from client to server only. Complete update of client data required to receive server changes. Row-level Tracking – whole row is transferred.
Number of tables from which data can be propagated	Multiple tables – as many as defined in the publication	One table per RDA method.
Types of tables that can be propagated	Different types of tables to control data flow Addition or removal of a table in the publication (server) is replicated automatically without reinitializing the subscription on the client	N/A Addition or removal of a table at the server is not automatically replicated to the client.
Constraints and indexes	Referential integrity constraints and indexes are replicated from server automatically.	Referential integrity constraints are not replicated, indexes are optionally replicated. Additional schema definition must be defined at the client.
Conflicts	Conflicts include data changed by different users and rows which did not apply because of an error. Resolution and management of conflicts on server Built-in and custom conflict resolvers supported.	Conflicts only include rows which did not apply because of an error. RDA does not detect if data was changed by a different user. Conflicts not managed, but are optionally reported in an error table on the client. No conflict resolvers.
Schema changes	Schema changes (such as add/drop columns, add/drop constraints, or changing column definition) can replicate.	Schema changes are not allowed. If the schema is changed, the client must drop the table at the client and pull all the data from server again. Depending on the schema change, a push can fail.
Identity columns	Manual and auto identity range handling. BigInt and Int columns supported.	Manual identity range handling. BigInt and Int columns supported.
Data/schema definition	Occurs at the server when the publication is configured and is automatically defined at the client when the subscription is created.	Data and schema definition occurs at the client when data is pulled from server to client.
Tools (UI)	Extensive tools to create and manage subscriptions, and monitoring tools to manage multiple subscriptions, watch performance, and sync times	No tools supported.
Server invasiveness	Tables and columns added to server database to manage replication.	No changes made to database on server.