lucene-solr-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Ahmet Arslan <iori...@yahoo.com>
Subject Re: solr joins
Date Sat, 01 Feb 2014 16:50:11 GMT
Hi Anand,

Mikhail writes about different join solutions and compares them. Here is couple of his write-ups.

http://blog.griddynamics.com/2012/08/block-join-query-performs.html

http://blog.griddynamics.com/2013/09/solr-block-join-support.html






On Saturday, February 1, 2014 9:18 AM, anand chandak <anand.chandak@oracle.com> wrote:
Folks, have a basic question regarding solr join, the wiki, 
<http://wiki.apache.org/solr/Join>  states : -

"Fields or other properties of the documents being joined "from" are not 
available for use in processing of the resulting set of "to" documents 
(ie: you can not return fields in the "from" documents as if they were a 
multivalued field on the "to" documents)".

I am finding it hard to understand the above limitation of solr 
join,does it means that unlike the traditional RDMS joins that can have 
columns from both the TO and FROM field, solr joins will only have 
fields from the TO  documents ? Is my understanding correct ?

Also, there's some difference with respect to scoring and towards that 
the wiki says :

"The Join query produces constant scores for all documents that match -- 
scores computed by the nested query for the "from" documents are not 
available to use in scoring the "to" documents" Does it mean the 
subquery's score is not available the main query? Is this behaviour true 
for the lucene join too ?

Basically, i am trying to understand where and how solr joins differ 
from lucene joins. Any pointers, much appreciated ?

I have posted same question on the stackoverflow 
<http://stackoverflow.com/questions/21480628/solr-join-vs-lucene-join>

Thanks,

Anand

Mime
View raw message