Whenever you delete any record(s), your RDBMS keeps them in Rollback segment, so in case if you issue a rollback command old data can be restored. In case you delete huge amount of record, you need to make sure that size of those records should not exceed what rollback segment can take care of.
If you need to delete all records you can truncate the table. on the other side write a small PL/SQL procedure and delete the inside loop based on row number and commit.
Alternatively you can run the same query from you SQL console multiple times. For example If you are working on oracle
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You can also use PreparedStatement#addBatch() in a loop to add every record to a batch and execute it only once afterwards. Costs only one DB hit instead of a hit for every row which would be far more expensive and slow.
Just to add, truncate isn't part of SQL92 and thus not supported by all database(version)s. Although it is less or more adopted by many DB's and likely to be part of the upcoming SQL92 successor. Since a certain version Informix supports Truncate as well, so this should be the way to go.