runtime view for merging two databases

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scala solist

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Nov 22, 2015, 1:22:47 PM11/22/15
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I have two databases with identical scheme, that belongs to different users. I'd like to create view where this two databases are efficiently merged without actually creating third databases that holds contents of both. The view should seek both databases for objects in predefined order. That order is used to resolve possible conflicts.

Can that be done with the orientdb engine? I understand that I always could rewrite queries to take into consideration not single but two databases, but this look tiresome and I would not like to reinvent the wheel.

Luigi Dell'Aquila

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Nov 23, 2015, 6:02:56 AM11/23/15
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Hi,

Unfortunately in current architecture you cannot execute queries that involve multiple databases, so I'm afraid you have to do it at application level

Thanks

Luigi

2015-11-22 19:22 GMT+01:00 scala solist <scala...@gmail.com>:
I have two databases with identical scheme, that belongs to different users. I'd like to create view where this two databases are efficiently merged without actually creating third databases that holds contents of both. The view should seek both databases for objects in predefined order. That order is used to resolve possible conflicts.

Can that be done with the orientdb engine? I understand that I always could rewrite queries to take into consideration not single but two databases, but this look tiresome and I would not like to reinvent the wheel.

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Luca Garulli

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Nov 23, 2015, 10:22:52 AM11/23/15
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We have the ODatabaseCompare class to compare 2 databases, but it provides you the diff. You could hack it as good starting point.

Best Regards,

Luca Garulli
Founder & CEO

scala solist

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Nov 23, 2015, 5:58:20 PM11/23/15
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I'd like to try another approach. The OrientDB client does not support multiple database connection. But what about thrid-party wrappers?

OrientDB is compatible with blueprints. Blueprints has the Sail module that provides SPARQL. SPARQL provide http://www.w3.org/TR/2013/REC-sparql11-federated-query-20130321/ federated query feature. That feature is reported as working here http://stackoverflow.com/questions/4841770/join-semantic-endpoints-in-sparql-query . And I found sail module that provides federation: http://mvnrepository.com/artifact/org.openrdf.sesame/sesame-sail-federation

I wonder if I could combine all that software to get federation in OrientDB. Is mentioned components compatible with each other? Is that large stack is ever sane?
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