Javadogs,For the purpose of clarifying this in the spec, I propose to add this to 14.6.9:
<proposed>Result expressions begin with either an instance of the candidate class (with an explicit or implicit "this") or an instance of a variable (using the variable name). The candidate tuples are the cartesian product of the candidate class and all variables used in the result. The result tuples are the tuples of the candidate class and all variables used in the result that satisfy the filter. The result is the collection of result expressions projected from the result tuples.
</proposed> Craig On Feb 6, 2006, at 12:34 PM, Craig Russell (JIRA) wrote:
[ http://issues.apache.org/jira/browse/JDO-246? page=comments#action_12365343 ]Craig Russell commented on JDO-246: ----------------------------------- The relevant parts of the specification are these:14.6.5 A variable that is not constrained with an explicit contains clause is constrained by the extent of the persistence capable class (including subclasses)....The semantics of contains is "exists", where the contains clause is used to filter instances. The meaning of the expression "emps.contains(e) && e.salary < param" is "there exists an e in the emps collection such that e.salary is less than param". This is the natural meaning of contains in the Java language, except where the expression is negated. If the variable is used in the result, then it need not be constrained....A portable query will constrain all variables with a contains clause in each side of an "OR" expression of the filter where the variable is used. Further, each variable must either be used in the query result or its contains clause must be the left expression of an "AND" expression where the variable is used in the right expression. That is, for each occurrence of an expression in the filter using the variable, there is a contains clause "ANDed" with the expression that constrains the possible values by the elements of a collection.14.6.9 If a variable or a field of a variable is included in the result, either directly or via navigation through the variable, then the semantics of the "contains" clause that include the variable change. In this case, all values of the variable that satisfy the filter are included in the result....If any result is a navigational expression, and a non-terminal field or variable has a null value for a particular set of conditions (the result calculation would throw NullPointerException), then the result is null for that result expression.Using the sample query data provided in the TCK in companyForQueryTests.xml and applying these to the cases at hand:SELECT this.name from org.apache.jdo.tck.pc.company.Department WHERE name.matches(".*e.*")The candidate tuples are {dept1, dept2}. Both satisfy the condition. The projection results in:{"Development"}, {Human Resources"}SELECT this.name, e.lastname from org.apache.jdo.tck.pc.company.Department WHERE name.matches (".*e.*") VARIABLES Employee eThis query is not portable because the variable employee is not constrained. This is not so useful because the relationship between department and employee is not constrained. Therefore the extent of department and the extent of employee are used.The candidate tuples are the cartesian product of {this, e}. There are two departments and five employees, so the cartesian product contains 10 tuples. The projection then is {{"Development", "emp1Last"}, {"Development", "emp2Last"}, {"Development", "emp3Last"}, {"Development", "emp4Last"}, {"Development", "emp5Last"}, {"Human Resouces", "emp1Last"}, {"Human Resouces", "emp2Last"}, {"Human Resouces", "emp3Last"}, {"Human Resouces", "emp4Last"}, {"Human Resouces", "emp5Last"}}.SELECT this.name, e.lastname from org.apache.jdo.tck.pc.company.Department WHERE name.matches (".*e.*") && this.employees.contains(Employee e)The candidate tuples are the cartesian product of {this, e}. There are two departments and five employees, so the cartesian product contains 10 tuples. Of these 10, only 5 satisfy the filter because of the emps.contains clause. These are {{dept1, emp1}, {dept1, emp2}, {dept1, emp3}, {dept2, emp4}, {dept2, emp5}}. The projection then is {{"Development", "emp1Last"}, {"Development", "emp2Last"}, {"Development", "emp3Last"}, {"Human Resouces", "emp4Last"}, {"Human Resouces", "emp5Last"}}SELECT employee.id, employee.manager.lastname FROM org.apache.jdo.tck.pc.company.Department WHERE employees.contains (employee) VARIABLES Employee employeeThe candidate tuples are this.employee. These are {{emp1}, {emp2}, {emp3}, {emp4}, {emp5}}. The projection then is {{1", "emp2Last"}, {2, "emp2Last"}, {3, "emp2Last"}, {4, null}, {5, null}}SELECT employee.manager.lastname FROM org.apache.jdo.tck.pc.company.Department WHERE employees.contains (employee) VARIABLES Employee employeeThe candidate tuples are this.employee. These are {{emp1}, {emp2}, {emp3}, {emp4}, {emp5}}. The projection then is {{"emp2Last"}, {"emp2Last"}, {"emp2Last"}, {null}, {null}}SELECT employee.lastname, project.name FROM org.apache.jdo.tck.pc.company.Department VARIABLES Employee employee; Project projectThis query is not portable because the variable employee is not constrained. The candidate tuples are the cartesian product of department, employee, and project. Two departments, five employees, and three projects result in 30 tuples. The result will contain 30 projections with each combination of employee.lastname and project.name repeated twice (one for each department).SELECT employee.lastname, project.name FROM org.apache.jdo.tck.pc.company.Department WHERE employees.contains (Employee employee)VARIABLES Employee employee; Project project;This query is not portable because the variable project is not constrained. The candidate tuples are the cartesian product of department, employee, and project. Two departments, five employees, and three projects result in 30 tuples. The filter reduces the results to 15 (the cartesian product of the {department, employee- who-works-in-the-department} and {project}. The result will contain 15 projections with each combination of employee.lastname and project.name.SELECT employee.lastname, project.name FROM org.apache.jdo.tck.pc.company.Department WHERE employees.contains (Employee employee) && employees.projects.contains(project) VARIABLES Employee employee; Project projectThis query is portable because all variables are constrained. The candidate tuples are the cartesian product of department, employee, and project. Two departments, five employees, and three projects result in 30 tuples. The filter reduces the result tuples to 7 {{dept1, emp1, proj3}, {dept1, emp2, proj1}, {dept1, emp2, proj2}, {dept1, emp3, proj1}, {dept1, emp3, proj2}, {dept2, emp4, proj3}, {dept2, emp5, proj3}, }. The result will contain 7 projections {{"emp1Last", "green"}, {"emp2Last", "orange"}, {"emp2Last", "blue"}, {"emp3Last", "orange"}, {"emp3Last", "blue"}, {"emp4Last", "green"}, {"emp5Last", "green"}}JPOX eliminates duplicates in the query result although DISTINCT is not specified. --------------------------------------------------------------------- -------------Key: JDO-246 URL: http://issues.apache.org/jira/browse/JDO-246 Project: JDO Type: Bug Components: tck20 Versions: JDO 2 beta Reporter: Michael Watzek Assignee: Erik Bengtson Fix For: JDO 2 rc1Test case NPEInResultExpr fails because the result of the query below is expected to contain duplicates. JPOX eliminates the duplicates. 14:22:55,046 (main) DEBUG [org.apache.jdo.tck] - Executing API query: SELECT employee.manager.lastname FROM org.apache.jdo.tck.pc.company.Department WHERE employees.contains (employee) VARIABLES Employee employee 14:22:55,078 (main) DEBUG [org.apache.jdo.tck] - Query result: [emp2Last, null]14:22:55,078 (main) DEBUG [org.apache.jdo.tck] - Wrong query result: expected: [emp2Last, null, emp2Last, emp2Last, emp2Last] got: [emp2Last, null]14:22:55,078 (main) INFO [org.apache.jdo.tck] - Exception during setUp or runtest: junit.framework.AssertionFailedError: Assertion A14.6.9-4 (NPEInResultExpr) failed:Wrong query result: expected: [emp2Last, null, emp2Last, emp2Last, emp2Last] got: [emp2Last, null] at junit.framework.Assert.fail(Assert.java:47) at org.apache.jdo.tck.JDO_Test.fail(JDO_Test.java:546)at org.apache.jdo.tck.query.QueryTest.queryFailed(QueryTest.java: 500) at org.apache.jdo.tck.query.QueryTest.checkQueryResultWithoutOrder (QueryTest.java:485)at org.apache.jdo.tck.query.QueryTest.execute(QueryTest.java:1189) at org.apache.jdo.tck.query.QueryTest.execute(QueryTest.java:1029)at org.apache.jdo.tck.query.QueryTest.executeAPIQuery (QueryTest.java:966) at org.apache.jdo.tck.query.QueryTest.executeAPIQuery (QueryTest.java:946) at org.apache.jdo.tck.query.result.NPEInResultExpr.testPositive (NPEInResultExpr.java:106)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:25)at java.lang.reflect.Method.invoke(Method.java:324) at junit.framework.TestCase.runTest(TestCase.java:154) at org.apache.jdo.tck.JDO_Test.runBare(JDO_Test.java:204) at junit.framework.TestResult$1.protect(TestResult.java:106) at junit.framework.TestResult.runProtected(TestResult.java:124) at junit.framework.TestResult.run(TestResult.java:109) at junit.framework.TestCase.run(TestCase.java:118) at junit.framework.TestSuite.runTest(TestSuite.java:208) at junit.framework.TestSuite.run(TestSuite.java:203) at junit.framework.TestSuite.runTest(TestSuite.java:208) at junit.framework.TestSuite.run(TestSuite.java:203) at junit.textui.TestRunner.doRun(TestRunner.java:116) at junit.textui.TestRunner.doRun(TestRunner.java:109)at org.apache.jdo.tck.util.BatchTestRunner.start (BatchTestRunner.java:120) at org.apache.jdo.tck.util.BatchTestRunner.main (BatchTestRunner.java:95)-- This message is automatically generated by JIRA. -If you think it was sent incorrectly contact one of the administrators:http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
Craig Russell Architect, Sun Java Enterprise System http://java.sun.com/products/jdo 408 276-5638 mailto:[EMAIL PROTECTED] P.S. A good JDO? O, Gasp!
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