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From "Vadim Kirilchuk (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-4768) Child Traversable To Parent Block Join Query
Date Mon, 11 Feb 2013 10:33:13 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-4768?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13575719#comment-13575719
] 

Vadim Kirilchuk commented on LUCENE-4768:
-----------------------------------------

Because when i have more fields and values - query becomes a real huge mess tree which is
slow and has duplicate leafs. Also i have cases like (f1: AB or f1:A or f1:B or f2: AB or
f2:A or f2:B), where AB is compound. So, i need to have 'clever' post constraint instead of
playing around with the query itself.

Anyway, let's come back to what i am trying to achieve by attached patch. If i use ToParentBJQ
i have no chance to traverse childs manually and i have to go through all childs in nextDoc,
but if i have many-many childs for single parent and first child is enough for my post condition
i can get a speedup. And as i said this query is more low level and current TPBJQ behavior
can easily be implemented with it. I already said in description that i want to know if anyone
needs this too...
                
> Child Traversable To Parent Block Join Query
> --------------------------------------------
>
>                 Key: LUCENE-4768
>                 URL: https://issues.apache.org/jira/browse/LUCENE-4768
>             Project: Lucene - Core
>          Issue Type: Improvement
>          Components: core/query/scoring
>         Environment: trunk
> git rev-parse HEAD
> 5cc88eaa41eb66236a0d4203cc81f1eed97c9a41
>            Reporter: Vadim Kirilchuk
>         Attachments: LUCENE-4768-draft.patch
>
>
> Hi everyone!
> Let me describe what i am trying to do:
> I have hierarchical documents ('car model' as parent, 'trim' as child) and use block
join queries to retrieve them. However, i am not happy with current behavior of ToParentBlockJoinQuery
which goes through all parent childs during nextDoc call (accumulating scores and freqs).
> Consider the following example, you have a query with a custom post condition on top
of such bjq: and during post condition you traverse scorers tree (doc-at-time) and want to
manually push child scorers of bjq one by one until condition passes or current parent have
no more childs.
> I am attaching the patch with query(and some tests) similar to ToParentBlockJoin but
with an ability to traverse childs. (i have to do weird instance of check and cast inside
my code) This is a draft only and i will be glad to hear if someone need it or to hear how
we can improve it. 
> P.s i believe that proposed query is more generic (low level) than ToParentBJQ and ToParentBJQ
can be extended from it and call nextChild() internally during nextDoc().
> Also, i think that the problem of traversing hierarchical documents is more complex as
lucene have only nextDoc API. What do you think about making api more hierarchy aware? One
level document is a special case of multi level document but not vice versa. WDYT?
> Thanks in advance.

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