Tagged Questions

In relational database design, a primary key can uniquely identify each row in a table. A primary key comprises a single column or a set of columns.

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13
votes
5answers
910 views

Why do primary keys have names of their own?

From a mathematical view, granted that a table has at most one primary key, it seems to be a shortsighted design decision to refer to primary keys by some arbitrary name instead of a simple table ...
2
votes
1answer
583 views

Question on Design for User + User Groups + User Types + Subscriptions Model

I am redeveloping an existing web application with both weak source code and a weak underlying database design. I'm trying to develop things in a way that future expansion will be much easier, ...
2
votes
4answers
448 views

Why would i get a duplicate write error of auto-generated primary key?

Hi I'm not a DBA so forgive my ignorance. I don't have access to administrator tools etc. However, I do know that we have a live server which is approaching capacity ie 80%-90% full perhaps. What is ...
7
votes
2answers
2k views

What's a good way to add a PRIMARY KEY to a large InnoDB table?

I have a table with around 30 million rows in MySQL 5.5 using the InnoDB storage engine. This table has a foreign key that links to another table with around 3 million rows. I want to add a primary ...
12
votes
2answers
1k views

Is there any tangible difference between a unique clustered index and a clustered primary key?

I understand that there may be a difference in meaning or intent between the two, but are there any behavioral or performance differences between a clustered primary key and a clustered unique index?
10
votes
4answers
3k views

Is there any benefit of a primary key that comprises all columns of the table?

I have a table with four columns that are all non-nullable, and the data is such that all four are needed to distinguish a unique record. This means that if I were to make a primary key, it would need ...
5
votes
3answers
1k views

Remove field from composite key and collate duplicate data

I'm looking for the best way to go about changing the primary key on a table in my DB without having to completely reinsert data from files again. The modification I'm going to make is going to ...
23
votes
3answers
13k views

What are the drawbacks with using UUID or GUID as a primary key?

I would like to build a distributed system. I need to store data in databases and it would be helpful to use an UUID or a GUID as a primary key on some tables. I assume it's a drawbacks with this ...
40
votes
3answers
9k views

Guid vs INT - Which is better as a primary key?

I've being reading around reasons to use or not Guid and int. int is smaller, faster, easy to remember, keeps a chronological sequence. And as for Guid, the only advantage I found is that it is ...
20
votes
3answers
4k views

Character vs Integer primary keys

I'm designing a database with multiple lookup tables containing possible attributes of the main entities. I'm thinking of using a 4 or 5-character key to identify these lookup values rather than an ...