Re: primary key index - Mailing list pgsql-general

From Sim Zacks
Subject Re: primary key index
Date
Msg-id f296td$22jl$1@news.hub.org
Whole thread Raw
In response to Re: primary key index  (Ron Johnson <ron.l.johnson@cox.net>)
Responses Re: primary key index
Re: primary key index
List 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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