To dig a bit deeper into zheap and PostgreSQL storage technology in general I decided to provide some more empirical information about space consumption. As stated in my previous blog post about zheap is more efficient in terms of storage consumption. The reasons are: The tuple header is much smaller Alignment has been improved The […]

In PostgreSQL table bloat has been a primary concern since the original MVCC model was conceived. Therefore we have decided to do a series of blog posts discussing this issue in more detail. What is table bloat in the first place? Table bloat means that a table and/or indexes are growing in size even if […]

© Laurenz Albe 2020 In many PostgreSQL databases, you never have to think or worry about tuning autovacuum. It runs automatically in the background and cleans up without getting in your way. But sometimes the default configuration is not good enough, and you have to tune autovacuum to make it work properly. This article presents […]

© Laurenz Albe 2020 Most people know that autovacuum is necessary to get rid of dead tuples. These dead tuples are a side effect of PostgreSQL’s MVCC implementation. So many people will be confused when they read that from PostgreSQL v13 on, commit b07642dbc adds support for autovacuuming insert-only tables (also known as “append-only tables”). […]

© Laurenz Albe 2019   Many people know that explicit table locks with LOCK TABLE are bad style and usually a consequence of bad design. The main reason is that they hamper concurrency and hence performance. Through a recent support case I learned that there are even worse effects of explicit table locks. Table locks […]

Looking at the type of PostgreSQL support requests, we have received recently, it is striking to see, how many of them are basically related to autovacuum and UPDATE in particular. Compared to other databases such as Oracle, PostgreSQL’s way of handling UPDATE and storage in general is quite different. Therefore people moving from Oracle to […]