Multi-User Features Available in All Cloudscape Products
The basic Cloudscape product contains some features that are useful for developing multi-user applications. These features include:
RmiJdbc
Cloudscape includes RmiJdbc, a simple connectivity framework, as well as a few Cloudscape customizations of RmiJdbc. RmiJdbc is freeware suitable for prototyping simple server scenarios. RmiJdbc provides JDBC connectivity, but not the many additional features of Cloudconnector.
Row-Level Locking
To support multiple users, Cloudscape provides the option of row-level or table-level locking. Table-level locking is preferable if there are few or no writes to the server, while row-level locking is essential for good performance if many clients write to the server concurrently. Cloudscapes optimizer tunes lock choice for queries automatically, or it can be controlled by the application.
Multiple Concurrency Levels
Cloudscape supports both SERIALIZABLE and READ COMMITTED isolation levels. READ COMMITTED provides greater concurrency for multiple users, and SERIALIZABLE provides greater consistency. See the Cloudscape Developers Guide for more information.
Multi-Connection and Multi-Threading
Cloudscape allows multiple simultaneous connections to a database, even in embedded mode. Cloudscape is also fully multi-threaded, and you can have multiple threads active at the same time. However, JDBC semantics impose some limitations on multi-threading. See the Cloudscape Developers Guide for more information.
Administrative Tools
Cloudscape provides some tools and features to assist database administrators. These tools are:
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Lock debugging VTI classes and deadlock monitoring
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Consistency checker
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On-line backup
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The ability to put a databases log on a separate device
These tools and features are discussed in part two of this book. See the chapters in that section for more information.
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