PK vs. Unique clustered indexes

Are there any differences, performance related or other wise, between having
a clustered primary key vs. a clustered unique key?
I'm am trying to ready a SQL2K server for replication. Some of the tables
in database A don't have a primary key but they do have a cluster unique
index. The index is named pk_table_A. I guess what I'd like to do, is drop
this index and recreated it as a primary key with the same columns and name.
Would this pose any type of possible problem ?
TIA,
BillyThat should be fine (assuming you don't already have a PK on the table). The PK carries with it a
unique index (you have control over whether it is to be a clustered index or not).
--
Tibor Karaszi, SQL Server MVP
http://www.karaszi.com/sqlserver/default.asp
http://www.solidqualitylearning.com/
"BillyDees" <BillyDees@.discussions.microsoft.com> wrote in message
news:1F6AAF9E-5E99-4776-ACF4-54B7FDB0EF89@.microsoft.com...
> Are there any differences, performance related or other wise, between having
> a clustered primary key vs. a clustered unique key?
> I'm am trying to ready a SQL2K server for replication. Some of the tables
> in database A don't have a primary key but they do have a cluster unique
> index. The index is named pk_table_A. I guess what I'd like to do, is drop
> this index and recreated it as a primary key with the same columns and name.
> Would this pose any type of possible problem ?
> TIA,
> Billy|||There is one thing to look out for and that is that unique indexes can be on
nullable columns (although they only allow one NULL value), but primary keys
can't. But if the columns in the unique index are non-nullable, it can be
replaced with a primary key, provided, as you say, that there isn't one
already on the table.
--
Jacco Schalkwijk
SQL Server MVP
"Tibor Karaszi" <tibor_please.no.email_karaszi@.hotmail.nomail.com> wrote in
message news:e$YRdIcRFHA.904@.tk2msftngp13.phx.gbl...
> That should be fine (assuming you don't already have a PK on the table).
> The PK carries with it a unique index (you have control over whether it is
> to be a clustered index or not).
> --
> Tibor Karaszi, SQL Server MVP
> http://www.karaszi.com/sqlserver/default.asp
> http://www.solidqualitylearning.com/
>
> "BillyDees" <BillyDees@.discussions.microsoft.com> wrote in message
> news:1F6AAF9E-5E99-4776-ACF4-54B7FDB0EF89@.microsoft.com...
>> Are there any differences, performance related or other wise, between
>> having
>> a clustered primary key vs. a clustered unique key?
>> I'm am trying to ready a SQL2K server for replication. Some of the
>> tables
>> in database A don't have a primary key but they do have a cluster unique
>> index. The index is named pk_table_A. I guess what I'd like to do, is
>> drop
>> this index and recreated it as a primary key with the same columns and
>> name.
>> Would this pose any type of possible problem ?
>> TIA,
>> Billy
>|||Good catch, Jacco!
--
Tibor Karaszi, SQL Server MVP
http://www.karaszi.com/sqlserver/default.asp
http://www.solidqualitylearning.com/
"Jacco Schalkwijk" <jacco.please.reply@.to.newsgroups.mvps.org.invalid> wrote in message
news:ueX1vNcRFHA.996@.TK2MSFTNGP09.phx.gbl...
> There is one thing to look out for and that is that unique indexes can be on nullable columns
> (although they only allow one NULL value), but primary keys can't. But if the columns in the
> unique index are non-nullable, it can be replaced with a primary key, provided, as you say, that
> there isn't one already on the table.
> --
> Jacco Schalkwijk
> SQL Server MVP
>
> "Tibor Karaszi" <tibor_please.no.email_karaszi@.hotmail.nomail.com> wrote in message
> news:e$YRdIcRFHA.904@.tk2msftngp13.phx.gbl...
>> That should be fine (assuming you don't already have a PK on the table). The PK carries with it a
>> unique index (you have control over whether it is to be a clustered index or not).
>> --
>> Tibor Karaszi, SQL Server MVP
>> http://www.karaszi.com/sqlserver/default.asp
>> http://www.solidqualitylearning.com/
>>
>> "BillyDees" <BillyDees@.discussions.microsoft.com> wrote in message
>> news:1F6AAF9E-5E99-4776-ACF4-54B7FDB0EF89@.microsoft.com...
>> Are there any differences, performance related or other wise, between having
>> a clustered primary key vs. a clustered unique key?
>> I'm am trying to ready a SQL2K server for replication. Some of the tables
>> in database A don't have a primary key but they do have a cluster unique
>> index. The index is named pk_table_A. I guess what I'd like to do, is drop
>> this index and recreated it as a primary key with the same columns and name.
>> Would this pose any type of possible problem ?
>> TIA,
>> Billy
>>
>|||Thanks to all of you for your replies. You confirmed what I thought but I
needed to be sure.
Billy
"Tibor Karaszi" wrote:
> Good catch, Jacco!
> --
> Tibor Karaszi, SQL Server MVP
> http://www.karaszi.com/sqlserver/default.asp
> http://www.solidqualitylearning.com/
>
> "Jacco Schalkwijk" <jacco.please.reply@.to.newsgroups.mvps.org.invalid> wrote in message
> news:ueX1vNcRFHA.996@.TK2MSFTNGP09.phx.gbl...
> > There is one thing to look out for and that is that unique indexes can be on nullable columns
> > (although they only allow one NULL value), but primary keys can't. But if the columns in the
> > unique index are non-nullable, it can be replaced with a primary key, provided, as you say, that
> > there isn't one already on the table.
> >
> > --
> > Jacco Schalkwijk
> > SQL Server MVP
> >
> >
> > "Tibor Karaszi" <tibor_please.no.email_karaszi@.hotmail.nomail.com> wrote in message
> > news:e$YRdIcRFHA.904@.tk2msftngp13.phx.gbl...
> >> That should be fine (assuming you don't already have a PK on the table). The PK carries with it a
> >> unique index (you have control over whether it is to be a clustered index or not).
> >>
> >> --
> >> Tibor Karaszi, SQL Server MVP
> >> http://www.karaszi.com/sqlserver/default.asp
> >> http://www.solidqualitylearning.com/
> >>
> >>
> >> "BillyDees" <BillyDees@.discussions.microsoft.com> wrote in message
> >> news:1F6AAF9E-5E99-4776-ACF4-54B7FDB0EF89@.microsoft.com...
> >> Are there any differences, performance related or other wise, between having
> >> a clustered primary key vs. a clustered unique key?
> >>
> >> I'm am trying to ready a SQL2K server for replication. Some of the tables
> >> in database A don't have a primary key but they do have a cluster unique
> >> index. The index is named pk_table_A. I guess what I'd like to do, is drop
> >> this index and recreated it as a primary key with the same columns and name.
> >> Would this pose any type of possible problem ?
> >>
> >> TIA,
> >> Billy
> >>
> >>
> >
> >
>
>