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Working with Cloudscape Properties
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Reference Manual |
Properties OverviewCloudscape lets you configure behavior or attributes of a system, a specific database, or a specific conglomerate (a table or index) through the use of properties. Examples of behavior or attributes that you can configure are:
In addition, you may sometimes be able to use properties to affect something as specific as the access path for the execution of a single query. See Overriding the Optimizer for a discussion of how these properties are used. This chapter does not discuss that type of property, which you set in a different way. For reference information about specific properties, see Chapter 5, "Cloudscape Properties". Scope of PropertiesYou use properties to configure a Cloudscape system, database, or conglomerate.
Persistence of PropertiesA database-wide property always has persistence. That is, its value is stored in the database. Typically, it is in effect until you explicitly change the property or until you set a system-wide property with precedence over database-wide properties (see Precedence of Properties). A system-wide property may or may not have persistence, depending on how you set it. If you set it programmatically, it persists only for the duration of the JVM of the application that set it. If you set it in the cloudscape.properties file, a property persists until:
Precedence of PropertiesThe search order for properties is:
This means, for example, that storage properties set for a specific conglomerate override all system-wide and database-wide storage properties; that system-wide properties set programmatically override database-wide properties and system-wide properties set in the cloudscape.properties file, and that database-wide properties override system-wide properties set in the cloudscape.properties file. Protection of Database-Wide PropertiesThere is one important exception to the search order for properties described above: When you set the cloudscape.database.propertiesOnly property to true, database-wide properties cannot be overridden by system-wide properties. This property ensures that a database's environment cannot be modified by the environment in which it is booted. Typically, most databases that are distributed or synchronization targets require this property to be set to true. Many applications running in an embedded environment may set this property to true for security reasons. Dynamic vs. Static PropertiesMost properties are dynamic; that means you can set them while Cloudscape is running, and their values change without requiring a reboot of Cloudscape. In some cases, this change takes place immediately; in some cases, it takes place at the next connection. Some properties are static, which means you cannot change their values while Cloudscape is running. You must restart or set them before (or while) starting Cloudscape. For more information, see Dynamic or Static Changes to Properties. |
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