Forum Post: RE: Null fields not getting compared using using data compare option of Toad for Oracle

When you get to the step "specify columns to uniquely identify each row", which columns are you including? If the table has a primary key, the primary key columns should show up automatically and you should not change them. If the table does NOT have a primary key, but there is a column (or two) that could be used as such, you may specify that. Do not specify a column with nulls as a key column. I think maybe that is what's happening. When you manually select key columns, Toad does a check to make sure that rows are uniquely identified, but Toad does not check to make sure that the columns to do not contains nulls. I'll fix that. If you don't have any key columns that do not contain nulls, then leave that step blank. It is better to leave it blank than to specify all columns. Finally, if the comparison is too slow, you can speed things up by changing the "Matching rows" option to "Ignore". Also, you might want to try the 12.12 beta. I have made some improvements queries that data compare uses in 12.12 (especially if no key columns are used).