Global Unique Identifiers

[Daniel Kiss]

Hi All,

I'm designing a database where it is required for each row in a table to 
have a unique identifier accross a bunch of running MySQL servers on a 
network.


I'm considering two options:

1. Have a two-column primary key, where the first column is a normal 
auto incremented ID field, the second identifies the database and 
contains a constant ID per server. Something like this:
CREATE TABLE MyTable (
    ROWID int unsigned not null auto_increment,
    DBID int unsigned not null,
    AnyData varchar(10) not null,
    PRIMARY KEY (ROWID, DBID)
);

INSERT INTO MyTable (DBID, AnyData) VALUES (8, 'Any text');

2. I would use a traditional one-column binary primary key populated by 
the built-in uuid() fuction of MySQL. Like this:
CREATE TABLE MyTable (
    ID binary(36) not null,
    AnyData varchar(10) not null,
    PRIMARY KEY (ID)
);

INSERT INTO MyTable (ID, AnyData) VALUES (uuid(), 'Any text');


In my view both solutions have their adventages and disadvantages. The 
first is more optimal in storage space and speed, the second is easier 
to maintain, administer and query.
And there is another aspect, which is needed to be tested, I guess... 
How fast is the second solution when I execute complex queries based on 
primary key relations? Does it pay to use the ease of the second 
solution? Anyone has any experience in similar problems?
What is your opinion?

Thanks,
    Daniel