SQL Diff ?

Hi List;

I have a very large table (52million rows) - I'm creating a copy of it to rid
it of 35G worth of dead space, then I'll do a sync, drop the original table
and rename table2.

Once I have the table2 as a copy of table1 what's the best way to select all
rows that have been changed, modified in table1 since the initial laod from
table1 into table2?

Also I'll need to delete any rows in table2 that no longer remain in table1.

There is no change date column
I could do something like select * from table1 where col1 || col2 || col3 etc
not in (select col1 || col2 || col3 etc from table2)

but this would be ineffecient & slow.

Anyone have a suggestion to do this in an efficient manner?

Thanks in advance

/Kevin