Ora-01555 Snapshot Too Old

[ixion]

If you are deleting more than 60 % of the rows and the table is very big, then consider the following option.
Create temp table from the original table in which you want to retain the rows.
Truncate original table.
Insert into original table from the temp table.

Tamil

CTAS
Then, Instead of insert, drop the original and rename the newly created table with less data! He'll also need to recreate triggers, indexes and FK's etc...