OK, this is not vitally important. Trying to relate some stuff I read in a theory book to Oracle. Per my theory book, databases can use two similiar nested loop type algorithms. 1. Use an index on the inner table and join for each row 2. When not using an index, can do 'block' level nested loop joins. I'm fairly certain that Oracle uses row level nested loop joins when tables are indexes. However, does it do 'block' level nested loop joins to improve performance when tables are not indexed. I do not know how to test for this. This is seperate from hash joins and sort merges. Anyone know? ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx put 'unsubscribe' in the subject line. -- Archives are at //www.freelists.org/archives/oracle-l/ FAQ is at //www.freelists.org/help/fom-serve/cache/1.html -----------------------------------------------------------------