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RE: Index advisor advising index on primary key



fixed

No, a primary key is by definition UNIQUE (and NOT NULL) and the access path already exists.

The question is, is the implicitly created index needed for primary key and/or unique constraints
different from the index created using CREATE INDEX.

I didn't think so, but the fact that you're being advised to create one would refute that.

Even so, I would think that the "access path" itself _HAS_ to be the same; no matter if it was in an
implicit index or an explicit one. So the only difference would be statistics kept by an implicit
index vs. an explicit index.



Charles Wilt
Software Engineer
CINTAS Corporation - IT 92B
513.701.1307

wiltc@xxxxxxxxxx


-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-
bounces@xxxxxxxxxxxx] On Behalf Of Jeff Crosby
Sent: Friday, April 11, 2008 9:33 AM
To: Midrange Systems Technical Discussion
Subject: Re: Index advisor advising index on primary key

Oooh. So if I did an ALTER TABLE and added a UNIQUE constraint on this
file, that might do it?

Mark S. Waterbury wrote:
Hi, Jeff:

You said "primary key" but did not indicate whether this column has a
"unique" constraint?

(I know that when you add a unique constraint to a table or file it
creates an index (access path) under the covers.)

Mark

> Jeff Crosby wrote:

...(snip)...
On our item master file, it is advising that I create an index on field
ITNBR. This file is an SQL table created via DDL (not DDS) and ITNBR
is
the primary key. Does this advice make sense? Why would it advise an
index on the primary key?



--
Jeff Crosby
UniPro Foodservice/Dilgard
260-422-7531
Opinions expressed are my own and not necessarily those of my company.
Unless I say so.


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