[jira] [Commented] (JCR-3493) OUTER JOIN tests expect incorrect results, which means that Jackrabbit excludes some valid results for OUTER JOINS

["Randall Hauch (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JCR-3493?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13556366#comment-13556366 ] 

Randall Hauch commented on JCR-3493:
------------------------------------

Thomas was kind enough to verify my assertions. Here's his response to original email inquiry (see [this thread|http://jackrabbit.510166.n4.nabble.com/Outer-join-behavior-in-the-TCK-tests-tt4657345.html]): 



To be sure, I converted the queries in this test to SQL statements that can be run against PostgreSQL. You can run them online using http://sqlfiddle.com/ (see below). I can fix the bug in Oak, but I'm not very familiar with this area in Jackrabbit 2.x. I guess the reason why Jackrabbit 2.x is broken is the same as for Oak: a "property is not null" restriction is pushed to the inner side of the outer join, which is wrong.

Test case:

-- schema
create table test(name varchar(255), prop1 int, prop2 int);
insert into test values('testroot/node1', 1, null);
insert into test values('testroot/node2', 1, 1);
insert into test values('testroot', null, null);

-- testRightOuterJoin1:
select l.name l, r.name r
from test as l 
right outer join test as r 
on l.prop1 = r.prop2
where r.name like 'testroot/%';

-- testRightOuterJoin2:
select l.name l, r.name r
from test as l 
right outer join test as r 
on l.prop2 = r.prop1
where r.name like 'testroot/%';

-- testLeftOuterJoin1:
select l.name l, r.name r
from test as l 
left outer join test as r 
on l.prop1 = r.prop2
where l.name like 'testroot/%';

-- testLeftOuterJoin2:
select l.name l, r.name r
from test as l 
left outer join test as r 
on l.prop2 = r.prop1
where l.name like 'testroot/%';
                
> OUTER JOIN tests expect incorrect results, which means that Jackrabbit excludes some valid results for OUTER JOINS
> ------------------------------------------------------------------------------------------------------------------
>
>                 Key: JCR-3493
>                 URL: https://issues.apache.org/jira/browse/JCR-3493
>             Project: Jackrabbit Content Repository
>          Issue Type: Bug
>          Components: jackrabbit-jcr-tests
>    Affects Versions: 2.5.2
>            Reporter: Randall Hauch
>
> Two of the OUTER JOIN tests appears to expect incorrect results:
> - org.apache.jackrabbit.test.api.query.qom.EquiJoinConditionTest#testRightOuterJoin1
> - org.apache.jackrabbit.test.api.query.qom.EquiJoinConditionTest#testLeftOuterJoin2
> Both tests are set up the same way: two nodes are created:
>   /testroot/workarea/node1 {jcr:primaryType=nt:unstructured, prop1=yikqysrwur}
>   /testroot/workarea/node1/node2 {jcr:primaryType=nt:unstructured, prop1=yikqysrwur, prop2=yikqysrwur, jcr:mixinTypes=[mix:referenceable], jcr:uuid=c9118bb2-922e-4612-acd7-7152105f5684}
> A single string is randomly generated and used for the values for "prop1" and "prop2", and only the second node is made to be "mix:referenceable". 
> The "testRightOuterJoin1" test runs this query:
>   SELECT * FROM [nt:unstructured] AS left 
>   RIGHT OUTER JOIN [nt:unstructured] AS right 
>   ON left.prop1 = right.prop2 
>   WHERE ISDESCENDANTNODE(right,'/testroot/workarea')
> The left side of the join has at least two tuples (one for "node1", one for "node2", and other nodes which do not have a 'prop1' value), and column of interest is the "prop1" column. Thus the left side tuples (or the parts we care about for the join) look like:
> 	[ node1, yikqysrwur ]
> 	[ node2, yikqysrwur ]
> 	[ …, <null> ]
> The right side of the join has only two tuples ("node1" and "node2") because of the "ISDESCENDANTNODE" criteria, and the only column of interest is the "prop2" column. Thus, the right side tuples (or the parts we care about for the join) look like:
> 	[ node1, <null> ]
> 	[ node2, yikqysrwur ]
> When we perform a RIGHT OUTER JOIN, we have to **include all the tuples on the right** even if they don't match a value on the left tuples. Thus, "node1" must be included in the results, and because it has a null value for the "prop2" column will not match any of the tuples on the left (since a null value is not equal to another null value in the case of join criteria). So the result set should contain these combinations of nodes:
> 	[ null, node1 ]
> 	[ node1, node2 ]
> 	[ node2, node2 ]
> However, the test expects the following result:
> 	[ node1, node2 ]
> 	[ node2, node2 ]
> This is incorrect to me, because it is missing the [node1, null] tuple that was on the right side of the join.

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