Did you ever wonder why VACUUM does not make your PostgreSQL tables smaller? Did you ever wonder why VACUUM does not shrink data files? Well, maybe this is the article you have been looking for. The point is: usually, space is not returned to the operating system after a cleanup and it is important to […]

© Laurenz Albe 2020 Many people consider recursive queries a difficult topic. Still, they enable you to do things that would otherwise be impossible in SQL. This articles gives a simple introduction with examples and shows the differences to Oracle’s implementation of recursive queries. Common table expressions (WITH clauses) A common table expression (CTE) can […]

Did you know that your temporary tables are not cleaned up by autovacuum? Autovacuum cleans tables automatically Since the days of PostgreSQL 8.0, the database has provided the miraculous autovacuum daemon which is in charge of cleaning tables and indexes. In many cases, the default configuration is absolutely ok and people don’t have to worry […]