Re: Null query result from oak queryimpl

[Thomas Mueller <mu...@adobe.com>]

Hi,

This is a bug, I created a new issue: OAK-1933 (with a simpler test case).

It's actually two bugs, the first is trying to remove an entries from an
unmodifiable set, the second problem is that jcr:createdBy could be a
multi-value property, such that it contains both "bar" and "baz". In that
case, the condition "jcr:content/@jcr:createdBy = 'bar') and
(jcr:content/@jcr:createdBy = 'baz'" would actually match the node.
Meaning the condition can't be ignored. With single valued-properties, a
property can't be both "bar" and "baz" at the same time, so it would never
match a node. But the query engine doesn't know whether a property can be
possibly multi-valued or not, so it has to be conservative and keep the
condition.

Regards,
Thomas



On 30/06/14 07:31, "Zsolt Grigore" <gr...@gmail.com> wrote:

>Dear all,
>
>During the process of migrating our codebase to the new jackrabbit
>implementation, I found an issue with a relatively complex Xpath
>query. I simplified it as much as I can so It should be easy to
>reproduce. Unfortunately i can't post the original query but i
>replaced the custom namespaces and properties with JCR ones so the
>example query looks pretty useless.
>
>//*[(((@jcr:primaryType = 'nt:file') and (jcr:content/@jcr:createdBy =
>'bar') and (jcr:content/@jcr:createdBy = 'baz')) or
>(jcr:content/@jcr:uuid = '81f5-33deafef08b6'))] order by
>jcr:content/@jcr:lastModified descending
>
>In the original query we filter on two types of resources, I replaced
>the primarytype with nt:file and for the other type of  resources we
>filter on a custom property (replaced with jcr:uuid). We add
>additional criterias to each of them but to reproduce the issue it is
>enough to add some to the first one so I added two createdBy
>constraint (as i found it is important two have the same key here with
>an AND otherwise I were not able to repoduce the Null result).
>
>I know that that Xpath has already deprecated but our codebase is
>already in production and it contains some really complex generated
>queries so before we start the refactoring we would like to know if
>this issue is related to our code or is this an issue with the new
>Jacrabbit implementation.
>
>During the investigation I found that the problem comes from the SQL2
>query which has been generated from XPath. In preparing the execution
>of the SQL2 query the underlying logic goes into this
>SelectorImpl.pushDown function to examine each and/or branches and
>possibly optimize the query but unfortunately my knowledge is not
>enough to determine what exactly happens at this point. From the JDocs
>i see that it tries to involve some logic to determine if it is
>possible to use indexes or not.
>As an additional information i can say that this query runs smoothly
>on the previous implementation. I tried searching around to get more
>information and possibly a fix but no luck so far. What could we do to
>fix this?
>
>
>Caused by: java.lang.UnsupportedOperationException: null
>at 
>com.google.common.collect.UnmodifiableIterator.remove(UnmodifiableIterator
>.java:43)
>at java.util.AbstractCollection.retainAll(AbstractCollection.java:406)
>at org.apache.jackrabbit.oak.query.ast.AndImpl.getInMap(AndImpl.java:113)
>at org.apache.jackrabbit.oak.query.ast.AndImpl.getInMap(AndImpl.java:101)
>at org.apache.jackrabbit.oak.query.ast.OrImpl.getInMap(OrImpl.java:108)
>at 
>org.apache.jackrabbit.oak.query.ast.OrImpl.restrictPushDownInList(OrImpl.j
>ava:166)
>at 
>org.apache.jackrabbit.oak.query.ast.OrImpl.restrictPushDown(OrImpl.java:15
>5)
>at 
>org.apache.jackrabbit.oak.query.ast.SelectorImpl.pushDown(SelectorImpl.jav
>a:263)
>at 
>org.apache.jackrabbit.oak.query.ast.SelectorImpl.prepare(SelectorImpl.java
>:277)
>at org.apache.jackrabbit.oak.query.QueryImpl.prepare(QueryImpl.java:531)
>//simple case no join
>at 
>org.apache.jackrabbit.oak.query.QueryEngineImpl.executeQuery(QueryEngineIm
>pl.java:167)
>at 
>org.apache.jackrabbit.oak.jcr.query.QueryManagerImpl.executeQuery(QueryMan
>agerImpl.java:132)
>at 
>org.apache.jackrabbit.oak.jcr.query.QueryImpl$2.perform(QueryImpl.java:101
>)
>at 
>org.apache.jackrabbit.oak.jcr.query.QueryImpl$2.perform(QueryImpl.java:98)
>at 
>org.apache.jackrabbit.oak.jcr.delegate.SessionDelegate.perform(SessionDele
>gate.java:308)
>at 
>org.apache.jackrabbit.oak.jcr.query.QueryImpl.execute(QueryImpl.java:97)
>
>Thanks, Zsolt