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Difference between synchronisation and join
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palmukesh
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PostPosted: Tue Jan 31, 2006 5:15 am 
Post subject: Difference between synchronisation and join

Can anybody tell me what is the difference between synchronisation and join when generating sql in webiXI.
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Dwayne Hoffpauir
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PostPosted: Tue Jan 31, 2006 3:58 pm 
Post subject: Re: Difference between synchronisation and join

Welcome to Bicon_mrgreen.gifB!

Join is preferred, and happens when all dimension objects are shared across contexts. If you have a dimension object that is not shared (belongs to say, only one context) you will see synchronization. There are limitations on which objects can be displayed together when contexts are synchronized (like unshared dimension from ONLY one context). It may be that this causes no problem at all. The advice is to confirm the results VERY carefully when you see synchronization. If you see join, you likely won't have those limitations or concerns.

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palmukesh
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PostPosted: Tue Jan 31, 2006 11:52 pm 
Post subject: Re: Difference between synchronisation and join

Thanks Dwayne,
Could you please explain the statement, "There are limitations on which objects can be displayed together when contexts are synchronized (like unshared dimension from ONLY one context)" in detail .
I am not getting what are you trying to say by this statement
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Dave Rathbun
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PostPosted: Wed Feb 01, 2006 12:13 am 
Post subject: Re: Difference between synchronisation and join

A join means that the two (or more) queries have the same number of dimension objects. A synchronization means they don't. Suppose you have a database with two fact tables and 6 dimension tables. Four of the dimension tables are shared, two are not. Suppose that A, B, C, and D are all shared dimension tables, E and F are only good for the second fact table.

If a query references A, B, C, and D along with F1 and F2 then (assuming proper universe design) Webi will generate two sql statements and return the results from F1 and F2 and join based on the selected dimensions. Now if you use table E or F along with A and B and F1 and F2 then you will still get shared dimensions from A and B but the extra dimensions from E and F can only appear in one of the two queries. The result is that you have two queries with different grain, and Webi will attempt to put together what it can (join common elements) and synchronize (cartesian) the rest.

It's late, I'm getting tired, and I have no idea if that will make sense tomorrow morning. icon_smile.gif

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Dwayne Hoffpauir
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PostPosted: Wed Feb 01, 2006 2:15 pm 
Post subject: Re: Difference between synchronisation and join

palmukesh wrote:
Could you please explain the statement, "There are limitations on which objects can be displayed together when contexts are synchronized (like unshared dimension from ONLY one context)" in detail.

In detail? Probably not, but I'll try with an example. Let's say you have a query that crosses two contexts. The SQL is split as follows:
Code:
Context1 -->> Dim1, Dim2, Fact1
Context2 -->> Dim1, Dim3, Fact2

Because the dimensions are not the same, this will result in a synchronization, not join. This may or may not cause a problem, but you will NOT be able to use Dim2 and Dim3 together in the same report block. You can use one or the other, but not both together.

Does that help at all?

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chris_c
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PostPosted: Tue Jun 27, 2006 2:27 pm 
Post subject: Re: Difference between synchronisation and join

Where does the Join occur?
Synchronization?

At the momment I have to assume that Synchronization occurs in the report since this behaves most like a linked data provider.

It seems logical to me for JOIN to occur at the database since the queries are largely identical BO could use the power of the database to process the join in a single select.

The reason I ask is because I am having chronic problems with a report, The query produces a Join between 5 contexts when I am in the edit mode I never have a problem, I get data back in a little over a minute. When I am in infoview I am getting about a 70% failure rate where the document will hang and never finish the refresh. In cases where it does finish the response time is normal.

The database is on Oracle 9
BO XI R2
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Sanjit
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PostPosted: Fri Nov 24, 2006 7:22 am 
Post subject: Re: Difference between synchronisation and join

Hi All

We are facing an issue in Business Objects XI release 2 webi on data synchronisation.

We have a report with 2 data providers. We have synchronised the two data providers on one object ONLY (i.e. Job No . ) . We have some variables in the report. These varaibles have an Assocaited Dimension (Edit Variable --> Associated dimension) with the synchronised object i.e. Job No . The report pulls in Varaibles we have created in the report and the Synchronised object 'job no' only.


The document property for the webi report (Edit Report --> Right Click on Report-- > Document properties) is set NOT to use "Auto Merge dimension" in Data Synchronisation Options (i.e. Automerged dimension option is unchecked). The reson to do this is we do not want all the objects in both the data providers to be synchronised.

The report refreshs perfect everytime. But when we export the Universe we get a Data synchronisation error (#Sync). We have to recheck the associated dimensions everytime to get the report working.

Did anyone face the same thing in any of thrie reports or am i missing something. I will really appretiate if someoone can let me know how to rectify this defect.

Cheers
Sanjit
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