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ER and Normalization
- Thread starter OOzy
- Start date
Hello.
PowerDesigner checks some aspects of the model when moving from the CDM to PDM but just in the case of flagging up redundancies, incomplete data etc. It's not normalization however.
When you generate from the PDM to the database it will check the script for inconsitsancies and incorrect syntaz but again won't do any normalization. Normalization is often conceptual and symantically based as opposed to syntax checking so would be hard to automate (although perhaps some wizards could be introduced).
Using a tool like PowerDesigner you can create your E/R model (Conceptual Data Model/CDM) and generate to the PDM (Physical Data Model). you can decide which items to generate and can rapidly round-trip between the two to speed up the process or nomalization.
In PD 9.5 (Atlas Edition) there is now the option to denormalize - that is to remodel the schema for faster quering/transactional capabilites etc, usually by splitting tables apart,introducing data redundancy, better 'postioning' of the data so data that is commonly used together is perhaps in the same table or across fewer tables etc.
Regards Jay
(See details below)
Denormalization may be accomplished in several ways:
· Horizontal partitioning is used to divide a table into multiple tables containing the same columns but fewer rows
· Vertical partitioning is used to divide a table into multiple tables containing the same number of rows but fewer columns
· Table collapsing is used to merge tables in order to eliminate the join between them
· Column denormalization is used to repeat a column in tables in order to avoid creating a join between tables
PowerDesigner checks some aspects of the model when moving from the CDM to PDM but just in the case of flagging up redundancies, incomplete data etc. It's not normalization however.
When you generate from the PDM to the database it will check the script for inconsitsancies and incorrect syntaz but again won't do any normalization. Normalization is often conceptual and symantically based as opposed to syntax checking so would be hard to automate (although perhaps some wizards could be introduced).
Using a tool like PowerDesigner you can create your E/R model (Conceptual Data Model/CDM) and generate to the PDM (Physical Data Model). you can decide which items to generate and can rapidly round-trip between the two to speed up the process or nomalization.
In PD 9.5 (Atlas Edition) there is now the option to denormalize - that is to remodel the schema for faster quering/transactional capabilites etc, usually by splitting tables apart,introducing data redundancy, better 'postioning' of the data so data that is commonly used together is perhaps in the same table or across fewer tables etc.
Regards Jay
(See details below)
Denormalization may be accomplished in several ways:
· Horizontal partitioning is used to divide a table into multiple tables containing the same columns but fewer rows
· Vertical partitioning is used to divide a table into multiple tables containing the same number of rows but fewer columns
· Table collapsing is used to merge tables in order to eliminate the join between them
· Column denormalization is used to repeat a column in tables in order to avoid creating a join between tables
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