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help / color / mirror / Atom feedFrom: David Johnston <polobo@yahoo.com>
To: pgsql-sql@postgresql.org
Subject: Re: Question about index/constraint definition in a table
Date: Wed, 9 Oct 2013 18:11:42 -0700 (PDT)
Message-ID: <1381367502833-5773942.post@n5.nabble.com> (raw)
In-Reply-To: <1381357909835-5773925.post@n5.nabble.com>
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<1381357909835-5773925.post@n5.nabble.com>
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David Johnston wrote
>
> JORGE MALDONADO wrote
>> I have a table as follows:
>> ------------------------------------------------
>> Table Artist Colaborations
>> ------------------------------------------------
>> * car_id (integer field, primary key)
>> * car_song (integer field, foreign key, foreign table is a catalog of
>> songs)
>> * car_artist (integer field, foreign key, foreign table is a catalog of
>> artists)
>>
>> So, I added 2 indexes to improve JOIN in queries:
>> 1. An index for car_song which accepts duplicates.
>> 2. An index for car_artist which accepts duplicates.
>>
>> Now, the combination of "car_song + car_artist" cannot be duplicated so I
>> think that adding a constraint on these 2 fields is the solution.
>>
>> My question: Is this the correct way to go?
>>
>> Respectfully,
>> Jorge Maldonado
> Yes. Why is it this is a question for you?
>
> Also, the car_id field becomes pointless since your new constraint is the
> true and natural PK.
>
> David J.
with index only scans it seems that defining a pair of unique indexes (and
no single column indexes) would have value. How much value I do not know.
Would still want to drop the artificial id field.
David J.
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To: pgsql-sql@postgresql.org
Cc: polobo@yahoo.com
Subject: Re: Question about index/constraint definition in a table
In-Reply-To: <1381367502833-5773942.post@n5.nabble.com>
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