I read this blog-post by Connor McDonald the other day about the Advanced Network Compression and network transfer savings. It reminded me of a feature not many know of and comes without an extra cost option. In fact, it’s on by default.
Large joins may use full scans and hash joins. If your tables are large enough, this will fill up your process working memory and start spilling to your temp-tablespace. At that time a few important effects come into play:
Lately I’ve been working a lot with large bulk-loads of data between Oracle databases. The loading is done over db-links and we needed to speed up some of the loads since parallel DML is not supported in distributed transactions.