[
https://issues.apache.org/jira/browse/OAK-7109?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16309376#comment-16309376
]
Dirk Rudolph commented on OAK-7109:
-----------------------------------
Hi [~catholicon] somehow the mail agent doesn't accept my mailings to oak-dev
(I'm subscribed and receiving mail but sending doesn't work ... anyway).
I checked the implementation of the optimisation and its not in dnf, as the
optimisation is not done on the negation normal form of the query (so not(a or
b) are not properly expanded to not(a) and not(b). For example (based on
org.apache.jackrabbit.oak.query.SQL2OptimiseQueryTest#optimiseAndOrAnd()):
{code}
given ([a]=1 or [b]=2 or ([c]=3 and not([d]=4 or [e]=5))) and [x]=6 <=> ([a]=1
or [b]=2 or ([c]=3 and [d]<>4 and [e]<>5))) and [x]=6
expected ([a]=1 and [x]=6), ([b]=2 and [x]=6), ([c]=3 and [d]<>4 and [e]<>5 and
[x]=6)
actual ((c = 3) and (not ((d = 4) or (e = 5)))) and (x = 6), (b = 2) and (x =
6), (a = 1) and (x = 6)
{code}
And even, assuming we would have the alternative being a DNF and facet counting
across unions would be supported merging the results from each of the queries
given to lucene, the result will still be wrong as each of the disjunctive
statements will not be mutually exclusive (as it would be with xor). So from my
perspective there is not way to get proper facet counts in that case from
consumer side and only the option of
b) filtering the documents based on the filter
c) passing all constraints to lucene
would work.
Regarding b) as from what I can see in the code base the nodes are not actually
read but only the permissions on their path are checked in
[FilteredSortedSetDocValuesFacetCounts.java#L91|https://github.com/apache/jackrabbit-oak/blob/trunk/oak-lucene/src/main/java/org/apache/jackrabbit/oak/plugins/index/lucene/util/FilteredSortedSetDocValuesFacetCounts.java#L91]
I will check further why our specific query doesn't get entirely passed to
lucene (or better which constraints are not taken into account beside the path
constraints). Anyway as a user of the jcr api I would expect a
RepositoryException (or any other) when I try to run a query with facet
extraction that no index can provide - similar to the exception I get when the
field I extract facets on is not stored.
> rep:facet returns wrong results for complex queries
> ---------------------------------------------------
>
> Key: OAK-7109
> URL: https://issues.apache.org/jira/browse/OAK-7109
> Project: Jackrabbit Oak
> Issue Type: Bug
> Components: lucene
> Affects Versions: 1.6.7
> Reporter: Dirk Rudolph
> Labels: facet
> Attachments: facetsInMultipleRoots.patch
>
>
> eComplex queries in that case are queries, which are passed to lucene not
> containing all original constraints. For example queries with multiple path
> restrictions like:
> {code}
> select [rep:facet(simple/tags)] from [nt:base] as a where contains(a.[*],
> 'ipsum') and (isdescendantnode(a,'/content1') or
> isdescendantnode(a,'/content2'))
> {code}
> In that particular case the index planer gives ":fulltext:ipsum" to lucene
> even though the index supports evaluating path constraints.
> As counting the facets happens on the raw result of lucene, the returned
> facets are incorrect. For example having the following content
> {code}
> /content1/test/foo
> + text = lorem ipsum
> - simple/
> + tags = tag1, tag2
> /content2/test/bar
> + text = lorem ipsum
> - simple/
> + tags = tag1, tag2
> /content3/test/bar
> + text = lorem ipsum
> - simple/
> + tags = tag1, tag2
> {code}
> the expected result for the dimensions of simple/tags and the query above is
> - tag1: 2
> - tag2: 2
> as the result set is 2 results long and all documents are equal. The actual
> result set is
> - tag1: 3
> - tag2: 3
> as the path constraint is not handled by lucene.
> To workaround that the only solution that came to my mind is building the
> [disjunctive normal
> form|https://en.wikipedia.org/wiki/Disjunctive_normal_form] of my complex
> query and executing a query for each of the disjunctive statements. As this
> is expanding exponentially its only a theoretical solution, nothing for
> production.
--
This message was sent by Atlassian JIRA
(v6.4.14#64029)
