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https://issues.apache.org/jira/browse/SOLR-6248?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14142063#comment-14142063
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Upayavira commented on SOLR-6248:
---------------------------------
I also, after a conversation with Hoss, have knocked up a MLTQuery parser.
I very much doubt your query parser will allow you to pass in a stream.body,
because the first few lines of
o.a.s.handler.component.SearchHandler.handleRequestBody() say:
{code:java}
if (req.getContentStreams() != null &&
req.getContentStreams().iterator().hasNext()) {
throw new SolrException(ErrorCode.BAD_REQUEST, "Search requests cannot
accept content streams");
}
{code}
This needs to be removed for stream.body to be available to the query parser.
I can post my patch later if anyone is interested. It doesn't have any tests
yet. My next task is to work out how to make it work across cores (recommend
docs in one core based upon docs in another).
Regarding the patch in this ticket, I'm curious why you needed a SolrCloud
specific query parser? Is it because the doc you are using might be in a
different shard?
Also, it appears from a cursory look that LWMoreLikeThis is a fork of Lucene's
MoreLikeThis class. Is there a reason that is needed, and if so, why isn't it
still in Lucene?
I expect to be working on my own version this week, and if what I produce can
be useful to others (via this ticket or otherwise), I'd be happy to contribute
it.
Thx!
> MoreLikeThis Query Parser
> -------------------------
>
> Key: SOLR-6248
> URL: https://issues.apache.org/jira/browse/SOLR-6248
> Project: Solr
> Issue Type: New Feature
> Reporter: Anshum Gupta
> Assignee: Anshum Gupta
> Attachments: SOLR-6248.patch
>
>
> 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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