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From: Martijn v Groningen <martijn.v.groningen@gmail.com>
Date: Fri, 14 Dec 2012 15:40:30 +0100
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Subject: Re: Re: Group by on multi fields
To: java-user@lucene.apache.org, dizh <dizh@neusoft.com>
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Not that I know of. The easiest way to functionally group across
multiple fields is to concatenate multiple field values into
a special group field. This isn't a flexible solution, but it doesn't
require modifying the Lucene code.

The other solution you can try is to group by ValueSource (is like a
function) instead by field. At the moment there isn't a concatenate
field values function implementation, but you can easily create that
yourself. This solution would be flexible (you can change the fields
you want to group by during runtime), but the grouping itself will be
more expensive (execution wise).

I hope this gives you some pointers to start with.

Martijn

On 11 December 2012 02:55, dizh <dizh@neusoft.com> wrote:
> Thanks to Martijn v Groningen.
>
> but , Is there anyone who has implemented this feature? just like SQL : s=
elect a1,a2,sum(a3) group by a1,a2;
>
> BTW: show me how to do is well too, Thank you=E3=80=82
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--=20
Met vriendelijke groet,

Martijn van Groningen

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