[GENERAL] Foreign keys and indexes

2007-06-05 Thread Marc Compte

Dear list,

This might be too basic for a question but I just couldn't find the 
answer so far.


Does PostgreSQL create an implicit index also for foreign keys? or must 
I create it explicitly?


Thank you,

Marc Compte

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Re: [GENERAL] Foreign keys and indexes

2007-06-05 Thread Marc Compte

Thanks to everyone for the prompt reply :)

Good thing about answers is when they raise up new questiosn, so you can 
keep on learning all the time.


This one answer, for instance, brings me another question. Does having a 
composite primary mean the system will create an individual index on 
each of the fields? or is the index created on the composition only?


For instance, in the implementation of a N:M relationship, declaring the 
primary as (foreign1, foreign2) will create two indexes? or just one?


Thanks again

Marc Compte

En/na Richard Broersma Jr ha escrit:
Does PostgreSQL create an implicit index also for foreign keys? or must 
I create it explicitly?



No, you foreign keys are not automatically indexed.  They only way they would 
be is if the FK is
part of a composite unique or primary key.  So you will probably have to create 
your one indexes
on FKs.

Regards,
Richard Broersma Jr.


  



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