I agree with Jerry. Take a look at the UUID() function.
http://dev.mysql.com/doc/refman/5.1/en/miscellaneous-functions.html#function_uuid
Second Life (http://secondlife.com) uses UUIDs to track millions and millions
of unique items every day.
Cheers....Fish
-----Original Message-----
>From: Jerry Schwartz <[EMAIL PROTECTED]>
>Sent: Aug 12, 2008 9:46 AM
>To: [EMAIL PROTECTED], mysql@lists.mysql.com
>Subject: RE: Unique Id generation
>
>>I try to generate a unique id for each row in a Mysql-InnoDB Table.
>>Because of many deletes I can't use an auto_increment column.
>>After a Mysql restart, the next value for an auto_increment-column is
>>max(auto_increment-column)+1, and I need a really unique id.
>>
>[JS] See if the UUID() function will suit you.
>>
>>My first solution looks like this:
>>I use a second table with an auto-increment-column, and add an insert
>>trigger to the first table.
>>The insert trigger adds a row in the second table and uses the
>>last_insert_id() to get the unique value.
>>The (last) row in the second table will never be deleted.
>>Does anybody confirm with this solution?
>>
>>###################################
>>drop table unique_id_messages_1;
>>create table unique_id_messages_1 (id bigint not null unique, subject
>>text);
>>
>>drop table id_sequences_1;
>>create table id_sequences_1 (id bigint not null primary key
>>auto_increment);
>>
>>drop trigger trg_unique_id_messages_1;
>>
>>DELIMITER |
>>
>>create trigger trg_unique_id_messages_1 BEFORE INSERT ON
>>unique_id_messages_1
>>FOR EACH ROW BEGIN
>> insert into id_sequences_1 values ();
>> set NEW.id = (select last_insert_id());
>>END;
>>|
>>DELIMITER ;
>>
>>insert into unique_id_messages_1 (subject) values ("x1");
>>insert into unique_id_messages_1 (subject) values ("x2");
>>insert into unique_id_messages_1 (subject) values ("x3");
>>insert into unique_id_messages_1 (subject) values ("x4");
>>select * from unique_id_messages_1;
>>###################################
>>
>>
>>Thanks in advance
>>
>>Rudi
>>
>>
>>
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