I think a database with all natural keys is unrealistic. For example if you
have a table that refers to people, are you going to use their name as a
primary key? Names change all the time due to things like marriage,
divorce, or trouble with the law. We have tables with 20 million rows which
reference back to a table of people, and if I used the person's name as key,
it would be a major pain when somebody's name changes. Even if there is
referential integrity, one person might be referred to by 25% of the 20
million rows, so the update would take quite a long time. Also the table
will be filled with dead rows and the indexes will likely be bloated. If I
want to clean that up, it will take a vacuum full or a cluster which will
lock the whole table and run for hours. If I use a surrogate key, I can
change their name in one row and be done with it.
Just my 2 cents.
Dave
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
