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
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
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
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
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
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
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
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
2013/7/27 Alvaro Herrera alvhe...@2ndquadrant.com
PostgreSQL implements unique constraints by way of unique indexes (and
it's likely that all RDBMSs do likewise). Also, the syntax to declare
unique indexes allows for more features than the unique constraints
syntax. For example, you can
I try to explain my point of view, also in my not so good English:
A primary key is defined by dr. Codd in relational model.
The key is used to identify a record. In good practice, you must always
define a primary key. Always.
The unique constraint will simply say: this value (or combination)
JORGE MALDONADO escribió:
I guess I am understanding that it is possible to set a unique index or a
unique constraint in a table, but I cannot fully understand the difference,
even though I have Google some articles about it. I will very much
appreciate any guidance.
The SQL standard does not
On Fri, Jul 26, 2013 at 3:19 PM, Alvaro Herrera
alvhe...@2ndquadrant.com wrote:
JORGE MALDONADO escribió:
I guess I am understanding that it is possible to set a unique index or a
unique constraint in a table, but I cannot fully understand the difference,
even though I have Google some
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