[jira] [Created] (OAK-5980) Bad Join Query Plan Used

["Thomas Mueller (JIRA)" <ji...@apache.org>]

Thomas Mueller created OAK-5980:
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             Summary: Bad Join Query Plan Used
                 Key: OAK-5980
                 URL: https://issues.apache.org/jira/browse/OAK-5980
             Project: Jackrabbit Oak
          Issue Type: Bug
          Components: query
            Reporter: Thomas Mueller
            Assignee: Thomas Mueller
             Fix For: 1.8


For a join query, where selectors are joined over ischildnode but also can use an index,
the selectors sometimes use the index instead of the much less
expensive parent join. Example:

{noformat}
select [a].* from [nt:unstructured] as [a]
inner join [nt:unstructured] as [b] on ischildnode([b], [a]) 
inner join [nt:unstructured] as [c] on ischildnode([c], [b]) 
inner join [nt:unstructured] as [d] on ischildnode([d], [c]) 
inner join [nt:unstructured] as [e] on ischildnode([e], [d]) 
where [a].[classname] = 'letter' 
and isdescendantnode([a], '/content') 
and [c].[classname] = 'chapter'         
and localname([b]) = 'chapters' 
and [e].[classname] = 'list' 
and localname([d]) = 'lists' 
and [e].[path] = cast('/content/abc' as path)
{noformat}

The order of selectors is sometimes wrong (not e, d, c, b, a), but
more importantly, selectors c and a use the index on className.




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