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From Shawn Heisey <>
Subject Re: MLT Query Parser
Date Wed, 06 Apr 2016 20:04:51 GMT
On 4/6/2016 11:07 AM, shamik wrote:
> Thanks Alessandro, that answers my doubt. in a nutshell, to make MLT Query
> parser work, you need to know the document id. I'm just curious as why this
> constraint has been added. This will not work for a bulk of use cases. For
> e.g. if we are trying to generate MLT based on a text or a keyword, how
> would I ever use this API ? My initial impression was that this was designed
> to work on a distributed mode.
> Now, this adds up a follow-up question as in which one is the right approach
> in a solr cloud mode. "mlt"request handler is off the equation since it's
> not supported. That leaves with MoreLikeThisComponent which has a known
> issue with performance. Is that the only availble solution then ?

The feature "More Like This/These" is built around the premise that you
are seeing one or more existing documents in a search result, and you
want to find more documents that are very similar to those.  This is why
you need an ID -- to tell Solr which document(s) you want to use as a
basis for the query.

If you're trying to find documents by keyword/text, that's just a
regular query; you don't need MLT.

MLT was not originally designed for distributed indexes.  Distributed
MLT is a *relatively* recent addition, and when I tried it, it was very
slow.  I do not know if the feature has changed much since it was
introduced three years ago.


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