cardinality for self join

[system]

-It is recomended “Always define cardinality, even for self-joins to avoid any cardinality warning messages.”
I have defined cardinality for self join (clasue used in self join is where grade=’A’) as 1:1( one to one)
While doing integrity check, it start giving me error.

If I remove cardinality universe does not show me any error.

Any thought -

why this is the case ???

Any implication of not setting cardinality for Self JOIN ???

thanks in advance

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GBS74 (BOB member since 2007-01-23)

[system]

Any implication of not setting cardinality for Self JOIN ???

No. I have never defined one for a self join.

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Mak 1 (BOB member since 2005-01-06)

[system]

Hi,

@GBS74

-It is recomended “Always define cardinality, even for self-joins to avoid any cardinality warning messages.”

Where do you have this from?

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Marek Chladny (BOB member since 2003-11-27)

[system]

Look at following post

120×120 10.4 KB

[Moderator Edit: Excessive carriage-returns removed, to allow this to format to each person’s screen size, rather than being a long, narrow, newspaper-column-wide entry. AMC] If you are not following the below standards for Universes, then you are creating a universe that most liklely can not be used by a user. 0.0 You must have a context for each FACT in the universe. If the the Report fires two queries and both queries take a great deal of time to run, the turn multisql off in designer. 4…

person has post this as one of standard used in universe

regards

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GBS74 (BOB member since 2007-01-23)

[system]

That part about setting cardinalities for self-restricting joins is wrong, IMHO.

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Marek Chladny (BOB member since 2003-11-27)

[system]

@Marek Chladny

That part about setting cardinalities for self-restricting joins is wrong, IMHO.

Marek,

I have to disagree; I always set cardinalities to 1:1 for self-joins to avoid getting the warning message.

GBS74, what error message are you getting when you have the cardinality set?

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anorak (BOB member since 2002-09-13)

[system]

I have to disagree; I always set cardinalities to 1:1 for self-joins to avoid getting the warning message.

Maybe its a certain patch level. I cannot remember ever doing this, but I have not used self joins for quite a while…

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Mak 1 (BOB member since 2005-01-06)

[system]

Hi Anorak,

@anorak

I always set cardinalities to 1:1 for self-joins to avoid getting the warning message.

Which BOBJ version do you use? I use self-restricting joins quite often and I do not set their cardinalities. The integrity check does not complain at all.

I use BO XI 3.1.

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Marek Chladny (BOB member since 2003-11-27)

[system]

@Marek Chladny

Hi Anorak,

@anorak

I always set cardinalities to 1:1 for self-joins to avoid getting the warning message.

Which BOBJ version do you use? I use self-restricting joins quite often and I do not set their cardinalities. The integrity check does not complain at all.

I use BO XI 3.1.

What about when you detect Contexts?

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anorak (BOB member since 2002-09-13)

[system]

@anorak

What about when you detect Contexts?

Ups, I don’t remember when I used it last time. I always set contexts manually. That gives me better control of what I am doing and why.

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Marek Chladny (BOB member since 2003-11-27)

[system]

@Marek Chladny

@anorak

What about when you detect Contexts?

Ups, I don’t remember when I used it last time. I always set contexts manually. That gives me better control of what I am doing and why.

Funny how different people work in different ways. I always auto-detect Contexts, and have never had any issues.

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anorak (BOB member since 2002-09-13)

[system]

@anorak

@Marek Chladny

@anorak

What about when you detect Contexts?

Ups, I don’t remember when I used it last time. I always set contexts manually. That gives me better control of what I am doing and why.

Funny how different people work in different ways. I always auto-detect Contexts, and have never had any issues.

Indeed, I always set these manually myself. Usually auto detect is fine for a dimensional model. The only exception to this is, if you are working with test data there is a chance that autodetect may not work correctly, as it depends on row counts.

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Mak 1 (BOB member since 2005-01-06)

[MarkP]

@Mak 1

@anorak

@Marek Chladny

@anorak

What about when you detect Contexts?

Ups, I don’t remember when I used it last time. I always set contexts manually. That gives me better control of what I am doing and why.

Funny how different people work in different ways. I always auto-detect Contexts, and have never had any issues.

Indeed, I always set these manually myself. Usually auto detect is fine for a dimensional model. The only exception to this is, if you are working with test data there is a chance that autodetect may not work correctly, as it depends on row counts.

I think you’ll find you’re thinking of cardinalities. #Derek

I’m with Anorak, set cardinalities manually and detect contexts using the button. The algorithm hasn’t really changed since they got it right years ago.

[system]

@Mark P

The algorithm hasn’t really changed since they got it right years ago.

Just beware of one-to-one joins at the end of a ‘path’ (or has this also now been covered by the detection algorithm?)

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anorak (BOB member since 2002-09-13)

[MarkP]

@anorak

@Mark P

The algorithm hasn’t really changed since they got it right years ago.

Just beware of one-to-one joins at the end of a ‘path’ (or has this also now been covered by the detection algorithm?)

1-1s are now detected. I think that’s the only change that’s been made since it was first introduced.