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https://issues.apache.org/jira/browse/SOLR-6248?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14071645#comment-14071645
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Steve Molloy commented on SOLR-6248:
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I meant passing in text as parameter as opposed to finding it in the index.
With current MLT handler (not component), you can pass it in as body or
stream.body to get documents similar to the text you pass in. In our case, we
use it to find documents in one collection similar to a document found in
another, or to some text directly provided by user. So, I know that at some
point the SearchHandler started rejecting search requests with stream body,
which would prevent this unless it could be achieved in another way. That's why
I'm asking. :)
> MoreLikeThis Query Parser
> -------------------------
>
> Key: SOLR-6248
> URL: https://issues.apache.org/jira/browse/SOLR-6248
> Project: Solr
> Issue Type: New Feature
> Reporter: Anshum Gupta
>
> MLT Component doesn't let people highlight/paginate and the handler comes
> with an cost of maintaining another piece in the config. Also, any changes to
> the default (number of results to be fetched etc.) /select handler need to be
> copied/synced with this handler too.
> Having an MLT QParser would let users get back docs based on a query for them
> to paginate, highlight etc. It would also give them the flexibility to use
> this anywhere i.e. q,fq,bq etc.
> A bit of history about MLT (thanks to Hoss)
> MLT Handler pre-dates the existence of QParsers and was meant to take an
> arbitrary query as input, find docs that match that
> query, club them together to find interesting terms, and then use those
> terms as if they were my main query to generate a main result set.
> This result would then be used as the set to facet, highlight etc.
> The flow: Query -> DocList(m) -> Bag (terms) -> Query -> DocList\(y)
> The MLT component on the other hand solved a very different purpose of
> augmenting the main result set. It is used to get similar docs for each of
> the doc in the main result set.
> DocSet\(n) -> n * Bag (terms) -> n * (Query) -> n * DocList(m)
> The new approach:
> All of this can be done better and cleaner (and makes more sense too) using
> an MLT QParser.
> An important thing to handle here is the case where the user doesn't have
> TermVectors, in which case, it does what happens right now i.e. parsing
> stored fields.
> Also, in case the user doesn't have a field (to be used for MLT) indexed, the
> field would need to be a TextField with an index analyzer defined. This
> analyzer will then be used to extract terms for MLT.
> In case of SolrCloud mode, '/get-termvectors' can be used after looking at
> the schema (if TermVectors are enabled for the field). If not, a /get call
> can be used to fetch the field and parse it.
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