Update dimension table and pre-join projection

Moderator: NorbertKrupa

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peleroy
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Update dimension table and pre-join projection

Post by peleroy » Sat Dec 20, 2014 6:01 pm

hello,

I have a pre-join projection for a Fact table, with a Dimension table.
I notice that when I update my Dimension table through a Merge statement, the pre-join projection is updated too.
I saw this in the Result of'the Explain on the merge query and also by the fact that dimension update takes a lot of time.
I am not interested in the update of the pre-join projection: the fact inserted before the update can have the old dimension value, important is that the newly inserted fact after the dim update have the new dim values.
Is there a way to prevent the dim update from updating the pre-join projection?

Thanks in advance for any hint,
Br

NorbertKrupa
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Re: Update dimension table and pre-join projection

Post by NorbertKrupa » Sun Dec 21, 2014 1:29 am

Are you updating on the join key?
Checkout vertica.tips for more Vertica resources.

id10t
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Re: Update dimension table and pre-join projection

Post by id10t » Sun Dec 21, 2014 9:52 am

Hi!

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Last edited by id10t on Mon May 04, 2015 9:12 pm, edited 1 time in total.

peleroy
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Re: Update dimension table and pre-join projection

Post by peleroy » Sun Dec 21, 2014 4:23 pm

For Norbertk: no, the join key is my dim primary key.
I possibly update other dim columns if dim key already exists or I insert a new dim record if dim key does not exist.

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