Question

I have 50GB mysql database (80 tables) that I need to delete some contents from it.
I have a reference table that contains list if product ids that needs to be deleted from the the other tables.

Now, the other tables can be 2 GB each, contains the items that needs to be deleted.

1. My question is: since it is not a small database, what is the safest way to delete
   the data in one shot in order to avoid problems?

2. What is the best method to verify the the entire data was deleted?

Answer 1

I am agree with Thirler that using of foreign keys is preferrable. It guarantees referential integrity and consisitency of the whole database.
I can believe that life sometimes requires more tricky logic.
So you could use manual queries like

delete from a where id in (select id from keys)  

You could delete all records at once or by range of keys or using LIMIT in DELETE. Proper index is a must.
To verify consistency you need function or query. For example:

create function check_consistency() returns boolean
begin
   return not exists(select * from child where id not in (select id from parent) ) 
       and not exists(select * from child2 where id not in (select id from parent) );
   -- and so on  
end