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I have been looking at data integration methods Global as view and Local as view, but I can not find any examples of how queries would be formed for these, could anyone give me examples of how these methods of data integration can be queried using GAV and LAV please

I am specifically asking about GAV and LAV here

I know that GAV (Global as view) is described over data sources and that LAV (local as view) is described over the mediated schema. However I am not totally sure what those terms mean, nor how they affect the query produced.

There is a wikipedia page for GAV, with no example of a query, and there isn't a wikipedia page for LAV sadly

AlanFoster
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    Could you give more information? What do you mean "data integration"? That's a very generic term, though it sounds like you mean them in a specific way. – John Saunders Jan 01 '12 at 23:58
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    @JohnSaunders I am specifically enquiring about global as view and local as view query structure, and query reformulation – AlanFoster Jan 02 '12 at 00:14
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    try puting more specific tags, I don't get the question. What kind of data, what is your tech stack, what is a query, which language? – oleksii Jan 02 '12 at 00:23
  • You seem to think other people know what "global as view" means. I've been doing this for over 35 years and have never heard of it. Please say what technologies you are using, where you heard these terms, etc. – John Saunders Jan 02 '12 at 07:58
  • If you intend the academic meaning as @Concerned: says below, then realize that most of us aren't in school right now, and that these terms mean nothing even to most people using technologies based on them. – John Saunders Jan 02 '12 at 08:00

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I think these terms are not widely used in industry - the only references I can see for them appear to arise from academic work. They apply to Enterprise Information Integration - a genre of technology where a client-side reporting or integration layer is placed over existing databases without actually persisting the data into a separate reporting database.

Essentially, 'Global As View' describes where data is transformed into a unified representation before reporting queries are issued. In a data warehouse (where the data is transformed and persisted into a separate database) this view would be the data warehouse tables. An EII tool can do this by issuing queries to the underlying data sources and merging it into the centralised schema. EII is not a widely used technology, though.

'Local as view' techniques query all the sources individually and then merge the result sets together. Conceptually, this is an act of making up several queries to the different sources that produce result sets in the same format, but source the data from wherever it is found in the underlying systems. The data integration is then done in the reporting layer.

ConcernedOfTunbridgeWells
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