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Comparison to PD to Teradata Tables

Former Member
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We are migrating data models, logical and physical from ERwin to PowerDesigner and looking for the best approach. Our thoughts are

1. Use ERwin to migrate to PD.
2. Perform a "Complete Compare" between newly created PD Physical table and the current Teradata Table to validate the content of the columns. Our ERwin DM may not be current view of the physical tables due to bad processes where developer add columns and Data architecture team was not in the loop of the development process.

Accepted Solutions (1)

Accepted Solutions (1)

Former Member
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I just realized that I did not copy in the specific question....I just provided the why I am am needing the answer.  So here is what I need answered.  The question is ....Is there a way to compare a PowerDesigner physical data model table with a Teradata data base table?...in ERwin this would be called a "complete compare"

GeorgeMcGeachie
Active Contributor
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Becky, you have a couple of choices here:

  1. reverse-engineer your Teradata database into a PD PDM, and compare that model with the PDM imported from ERwin
  2. compare any PDM to the database via these options on the Database menu:
    • Apply Model Changes to Database
    • Update Model from Database

I would go for option 1, for several reasons:

  • no risk of updating the model or database accidentally
  • you will need a reverse-engineered PDM of the current state anyway
  • later on, model-to-model comparisons avoid the differences you might get when comparing the metadata in a model with the metadata extracted from a database, just because the model can hold extra metadata

If I were you, I'd also run Complete Compare against the database in ERwin, and compare the differences reported by ERwin and PD as part of your model migration checks.

Former Member
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OK. we are getting closer but since I am a new user to this...I am missing some information.  ERwin has a Complete Compare.  Does PD have a comparable tool built in?  If yes, how do I access that tool?  We definitely want to migrate our current ERwin model to PD.  We do not want to start with the creation of PD from the teradata tables. We just want to do the final checks between TD and PD after creation.  We can do this before PD creation from ERwin but want to know if PD has this same kind of tool.  Does it?

Former Member
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I am working with a client version now....I do not see a Database Menu. Could that be my issue?

GeorgeMcGeachie
Active Contributor
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If you don't see a Database menu, your active model (based on the diagram you're looking at) isn't a PDM

GeorgeMcGeachie
Active Contributor
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or you don't have the PDM diagram open - necessary for the Database menu to appear

GeorgeMcGeachie
Active Contributor
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You access the model comparison via the Database menu options I mentioned, the Tools menu (Merge or Compare models, model generation), and via repository check in/out.

By the way, I think ERwin's 'Complete Compare' is bi-directional, the PD one isn't - stuff only moves from the left model to the right one.

If you don't create an 'as-is' PD model of the Teradata database, how are you going to be able to see a complete history of the changes you make? I suggest that the reverse-engineered model becomes your new master, which you freeze in the repository as version 1, before making any changes to it. Then merge in the required changes from model you imported from ERwin to form version 2.

Former Member
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OK. I was thinking that we were going to ODBC connect directly to our Teradata DB and specifically our indivual table to perform a comparison.  ....rather than creating a PD "image" of our Teradata DB table in PowerDesigner.  Hmmm.  Does PD ODBC connect directly table by table?  After we answer this then lets address our history of changes.  If left to right then shouldnt the right retain the historical changes?

Former Member
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We are not updating our Teradata DB tables.  Only the missing columns to our PD tables. It would be one direction left to right.

former_member192453
Active Participant
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Hi Becky,

George has been guiding you in the right direction.

Here are the basic steps you can try to obtain the results that you have described:

1) import your Erwin model into PowerDesigner

2) in the PDM, select the Database->Update model from Database menu

3) connect to your Teradata database via ODBC

4) select the objects that you ant to reverse engineer and click OK

5) you will be presented with a Merge model window (the left side is from the database and the right side the local PDM)

6) decide which actions you want to apply to the local PDM and click OK.


Essentially, when you reverse engineer (update from database), PowerDesigner is creating a PDM in memory. This PDM is then compared with the local PDM and then you can select the actions that you want applied to the local PDM.

-Anthony

Former Member
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Thank you George and Anthony!  We will be testing this out soon.

Answers (1)

Answers (1)

marc_ledier
Active Participant
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Hi

Depending on the ERwin version you may want to try the import from PowerDesigner.

It allows to create separate but linked CDM/LDM/PDM from one ERwin xml export.

I suggest you try both direction on a small ERwin model and choose your prefered one.

Marc