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From: Zheng Lin Edwin Yeo <edwinyeozl@gmail.com>
Date: Wed, 3 May 2017 13:20:05 +0800
Message-ID: <CAF2DzVUHqnAMiPYePZo6KSLj6HPbMZqVf=4U_Y=LFBEsG27ZMg@mail.gmail.com>
Subject: Re: Joining more than 2 collections
To: solr-user@lucene.apache.org
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archived-at: Wed, 03 May 2017 05:20:12 -0000

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Hi Joel,

Thanks for the info.

Regards,
Edwin


On 3 May 2017 at 02:04, Joel Bernstein <joelsolr@gmail.com> wrote:

> Also take a look at the documentation for the "fetch" streaming expression.
>
> Joel Bernstein
> http://joelsolr.blogspot.com/
>
> On Tue, May 2, 2017 at 2:03 PM, Joel Bernstein <joelsolr@gmail.com> wrote:
>
> > Yes you join more then one collection with Streaming Expressions. Here
> are
> > a few things to keep in mind.
> >
> > * You'll likely want to use the parallel function around the largest
> join.
> > You'll need to use the join keys as the partitionKeys.
> > * innerJoin: requires that the streams be sorted on the join keys.
> > * innerHashJoin: has no sorting requirement.
> >
> > So a strategy for a three collection join might look like this:
> >
> > innerHashJoin(parallel(innerJoin(bigStream, bigStream)), smallerStream)
> >
> > The largest join can be done in parallel using an innerJoin. You can then
> > wrap the stream coming out of the parallel function in an innerHashJoin
> to
> > join it to another stream.
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Joel Bernstein
> > http://joelsolr.blogspot.com/
> >
> > On Mon, May 1, 2017 at 9:42 PM, Zheng Lin Edwin Yeo <
> edwinyeozl@gmail.com>
> > wrote:
> >
> >> Hi,
> >>
> >> Is it possible to join more than 2 collections using one of the
> streaming
> >> expressions (Eg: innerJoin)? If not, is there other ways we can do it?
> >>
> >> Currently, I may need to join 3 or 4 collections together, and to output
> >> selected fields from all these collections together.
> >>
> >> I'm using Solr 6.4.2.
> >>
> >> Regards,
> >> Edwin
> >>
> >
> >
>

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