Re: [SQL] Unique index VS unique constraint

2013-10-05 Thread JORGE MALDONADO
So, let´s say that I have the following simple example table: 1. cus_id 2. cus_name 3. Other fields . . . Where cus_id is the primary key. And let´s also say that I want cus_name to be unique. I have the option to create a unique constraint or a unique index. What would be the best decision and

Re: [SQL] Unique index VS unique constraint

2013-10-05 Thread Sergey Konoplev
On Sat, Oct 5, 2013 at 3:24 PM, JORGE MALDONADO jorgemal1...@gmail.com wrote: So, let´s say that I have the following simple example table: 1. cus_id 2. cus_name 3. Other fields . . . Where cus_id is the primary key. And let´s also say that I want cus_name to be unique. I have the option

[SQL] Unique index VS unique constraint

2013-10-04 Thread JORGE MALDONADO
I have search for information about the difference between unique index and unique constraint in PostgreSQL without getting to a specific answer, so I kindly ask for an explanation that helps me clarify such concept. Respectfully, Jorge Maldonado

Re: [SQL] Unique index VS unique constraint

2013-10-04 Thread luca...@gmail.com
Il 04/10/2013 18:48, JORGE MALDONADO ha scritto: I have search for information about the difference between unique index and unique constraint in PostgreSQL without getting to a specific answer, so I kindly ask for an explanation that helps me clarify such concept. 2 main differences. First

Re: [SQL] Unique index VS unique constraint

2013-10-04 Thread Adrian Klaver
On 10/04/2013 09:48 AM, JORGE MALDONADO wrote: I have search for information about the difference between unique index and unique constraint in PostgreSQL without getting to a specific answer, so I kindly ask for an explanation that helps me clarify such concept. The way I think of it is, that

Re: [SQL] Unique index VS unique constraint

2013-10-04 Thread Adrian Klaver
On 10/04/2013 10:41 AM, luca...@gmail.com wrote: Il 04/10/2013 18:48, JORGE MALDONADO ha scritto: I have search for information about the difference between unique index and unique constraint in PostgreSQL without getting to a specific answer, so I kindly ask for an explanation that helps me

Re: [SQL] Unique index VS unique constraint

2013-10-04 Thread David Johnston
JORGE MALDONADO wrote I have search for information about the difference between unique index and unique constraint in PostgreSQL without getting to a specific answer, so I kindly ask for an explanation that helps me clarify such concept. A constraint says what valid data looks like. An

Re: [SQL] Unique index VS unique constraint

2013-10-04 Thread Steve Grey
Unique indexes can be partial, i.e. defined with a where clause (that must be included in a query so that PostgreSQL knows to use that index) whereas unique constraints cannot. JORGE MALDONADO wrote I have search for information about the difference between unique index and unique constraint in

Re: [SQL] Unique index VS unique constraint

2013-10-04 Thread David Johnston
Steve Grey-2 wrote Unique indexes can be partial, i.e. defined with a where clause (that must be included in a query so that PostgreSQL knows to use that index) whereas unique constraints cannot. This implies there can be data in the table but not in the index and thus said index is not part