Data Model

Database vs Data Model

You query the data model, not the database tables. There is no security when you query the database, a database user that has access to the tables can always see all objects. Furthermore, the table names, column names, and data types will change without prior notice. Some table and column names have inconsistent names, this is known.

The data model consists of a number of tables that can be accessed using SQL'92 queries; a subset of the standard is supported. The API has several methods on SchedulerSession, for example, to query the data model. For example, to select all jobs in status Queued, you specify the following query in the executeObjectQuery method of SchedulerSession:

select Job.* from Job where Job.Status = 'Q'

All SQL queries use a subset of the ANSI '92 SQL language.

Note: Depending on the underlying database, these functions may not always return the expected value. Please see the documentation of your database vendor for implementation specifications.

Warning: Querying the database tables directly is not supported. Table names, column names, and data types will change without prior notice. You query the data model layer instead.

Storing Strings in the Database

Due to restrictions in supported databases, strings cannot end with a whitespace character such as a space or tab. When you attempt to set a description of an object, for example a Queue, to a String which has a trailing whitespace character, the persist will fail; this is by design.

Classes