Re: Advice on index and constraint definition

JORGE MALDONADO wrote
> Hi,
>
> I have a table like the one below where all of the fields are foreign keys
> except "prv_id" which is the primary key:
>
> prv_id                      serial
> prv_user_id             inetger
> prv_client_id            integer
> prv_customs_id       integer
> prv_patent_id          integer
> prv_doctype_id        integer
>
>
> a) I read that it is a good idea to add an index for every foreign key in
> order to improve record management when selecting data for example.
>
> b) I need to avoid duplicates in the combination of fields "prv_user_id,
> prv_client_id, prv_customs_id, prv_patent_id, prv_doctype_id" so this
> drives me to set a constraint with such a field combination.
>
> Are statements (a) and (b) correct?
>
> Respectfully,
> Jorge Maldonado

Both pieces of advice are valid though I'd generally question a design that
uses 5 foreign keys on a matching table.  Most matching tables match two
items.  Now if, say,  user-client is already foreign key then that pair is
only a single constraint and you wouldn't need individual constraints on
each field.

David J.




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