From: | Sim Zacks <sim(at)compulab(dot)co(dot)il> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: primary key index |
Date: | 2007-05-14 09:32:36 |
Message-ID: | f296td$22jl$1@news.hub.org |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-general |
It is mixture of looking and knowing where to look. I read the section on indexes where it says that
PostGreSQL creates a unique index, but I didn't see an index on the table so I didn't know if it was
implicit or if for some reason my primary keys weren't becoming indexes. I didn't see the create
table documentation which states that it is not necessary to explicitly create them.
Thank you for your help.
> PostgreSQL automatically creates a unique index when a unique constraint
> or a primary key is defined for a table. The index covers the columns that
> make up the primary key or unique columns (a multicolumn index, if appropriate),
> and is the mechanism that enforces the constraint.
Ron Johnson wrote:
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> On 05/14/07 03:27, Sim Zacks wrote:
>> Is a primary key an implicit index, or if I want to join on that field
>> is it also worthwhile to make an explicit index?
>
> On-line documentation is such a wonderful resource...
>
> http://www.postgresql.org/docs/7.3/interactive/sql-createtable.html
>
> PostgreSQL automatically creates an index for each unique
> constraint and primary key constraint to enforce the uniqueness.
> Thus, it is not necessary to create an explicit index for
> primary key columns.
>
> (Yes, I purposefully used the doc set of an ancient version.)
>
> - --
> Ron Johnson, Jr.
> Jefferson LA USA
>
> Give a man a fish, and he eats for a day.
> Hit him with a fish, and he goes away for good!
>
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