In previous post in the series I wrote about how to interpret single line in explain analyze output, it's structure, and later on described all basic data-getting operations (nodes in explain tree). Today, we'll move towards more complicated operations.

If you worked with certain other (than PostgreSQL) open source database, you might wonder why PostgreSQL doesn't have MERGE, and why UPSERT example in documentation is so complicated. Well, let's try to answer the question, and look into some alternatives.