From: | salah jubeh <s_jubeh(at)yahoo(dot)com> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: variant column type |
Date: | 2011-07-27 09:49:30 |
Message-ID: | 1311760170.49000.YahooMailRC@web161503.mail.bf1.yahoo.com |
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Lists: | pgsql-general |
Thanks for the help, and for different design options it really helped me. I had
a look on vertical design and horizontal design and this is some cons and pros
in general for vertical design
Advantages:
• Avoid null values and utilize storage
• Avoid constant schema changes due to adding columns
• Avoid performance issues which may encountered when a the table is very
wide for specific queries
Disadvantages
• Queries written against the vertical design became cumbersome.
• Multiple joins to pull back each attribute.
• Data needs to be converted to the horizontal design in many cases so you
need the contribution modules such as table funcs
• Data domains are problematic and hacks here can be used such as fix your
attributes, or using many tables....
------------------------
the car speed is 240
the car has an airbag
Here the first value is integer and the second value is boolean. Consider that I
have this table structure
feature (feature id feature name)
car (car id, .... )
car_feature (car id, feature id, value). the value attribute might have
different domains. How can I model this using postgres and using ANSI compliant
design ?
Regards
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