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Re: [geomesa-users] Geotools Join queries
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When you've got time, definitely try out the Spark SQL support. It's efficient and quite flexible. And we need more people kicking the tires to make it robust.
> On Apr 11, 2017, at 6:20 PM, David Boyd <dboyd@xxxxxxxxxxxxxxxxx> wrote:
>
> Emilio:
>
> Thanks. That is what I thought. Yeah, such joins are very expensive.
>
> The plan was to eventually go to spark, but I don't think
> we have the schedule time. Well, brute force and ignorance to the rescue.
>
>
>> On 4/11/17 10:15 PM, Emilio Lahr-Vivaz wrote:
>> Hi Dave,
>>
>> We don't support joins through the query like that - joins against a no-sql database tend to be very expensive. But we do have a few options. If available, probably the best approach is to use our spark support and do an in-memory join. If not, we also have a join WPS (web process service) that you can use, but it limits the features from the first set to 128: https://github.com/locationtech/geomesa/blob/master/geomesa-accumulo/geomesa-accumulo-datastore/src/main/scala/org/locationtech/geomesa/accumulo/process/JoinProcess.scala
>>
>> If you want to use spark, I can try to find some examples for you.
>>
>> Thanks,
>>
>> Emilio
>>
>>
>>> On 04/11/2017 06:05 PM, David Boyd wrote:
>>> I have a feeling this is not supported but I would ask.
>>>
>>> I have two featuretypes, with a common foreign_key between them.
>>> I want to join on that foreign_key and retrieve columns/properties from
>>> both featuretypes.
>>>
>>> I found an example of this in the geotools documentation, but I can't get it to work.
>>> I simply can't find the name of the join column to retrieve.
>>>
>>> Below is my code:
>>>
>>>> String propertynames[] = { "\"GDELTArtifactRecordset.SourceFileName\"","\"GDELTArtifactRecordset.GlobalEventID\"","b.EventCode\""};
>>>> FilterFactory2 ff = CommonFactoryFinder.getFilterFactory2();
>>>> Filter jfilter = ff.equals(ff.property("GDELTArtifactREcordset.GlobalEventID"), ff.property("b.GlobalEventID"));
>>>> Query query = new Query("GDELTArtifactRecordset");
>>>> query.setPropertyNames(propertynames);
>>>>
>>>> Join join = new Join("EventRecordset", jfilter);
>>>> join.setAlias("b");
>>>> query.getJoins().add(join);
>>>>
>>>> query.setFilter(ff.greaterOrEqual(ff.property("GDELTArtifactRecordset.GlobalEventID"), ff.literal(545650000)));
>>>> query.setStartIndex(0);
>>>> CachedRowSet rowset = searchPersistor.search(query).getResults();
>>> I have tried numerous various of the returned join column, but it will no accept any column not in my GDELTArtifactRecordset.
>>>
>>>
>>
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>
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> David W. Boyd
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