In SQL, the concept of foreign keys is an important one that can be found in all professional databases used in the industry. The core idea is to prevent your PostgreSQL database from storing inconsistent data by enforcing constraints ensuring the correctness of your tables (at least as far as relations between objects are concerned). […]

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 […]

The PostgreSQL caching system has always been a bit of a miracle to many people and many have asked me during consulting or training sessions: How can I figure out what the PostgreSQL I/O cache really contains? What is in shared buffers and how can one figure out? This post will answer this kind of […]

A lot has been written about configuring postgresql.conf, postgresql.auto.conf and so on. However, sometimes it requires to take a second look in order to understand, how PostgreSQL really handles configuration parameters. You will notice that PostgreSQL configuration offers more than meets the eye at first glance. So let us dive into PostgreSQL GUCs and configuration […]

When digging into PostgreSQL performance it is always good to know, which option one has to spot performance problems and to figure out, what is really going on on a server. Finding slow queries and performance weak spots is therefore exactly what this post is all about. There are many ways to approach performance problems. […]

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 […]

When running PostgreSQL on a production system, it might happen that you are facing table bloat. As you might know PostgreSQL has to copy a row on UPDATE to ensure that concurrent transactions can still see the data. At some point VACUUM can clean out dead rows but if transactions are too long, this cleanup […]

SQL is a must, if you want to be a Data Analyst or a Data Scientist. However, every once in a while people are wondering, why a result is the way it is. While on the road in Berlin (Germany) the other day, I have found a fairly interesting scenario, which is pretty counterintuitive to […]

As a professional PostgreSQL support company, we see a lot of SQL performance stuff, which is often worth sharing. One of those noteworthy things, which might be interesting to you, the reader, happened this week when I was out on a business trip to Berlin, Germany. This (excellent) customer was making extensive use of windowing […]

What does PostgreSQL Full-Text-Search have to do with VACUUM? Many readers might actually be surprised that there might be a relevant connection worth talking about at all. However, those two topics are more closely related, than people might actually think. The reason is buried deep inside the code and many people might not be aware […]

The COPY command in PostgreSQL is a simple way to copy data between a file and a table. COPY can either copy the content of a table to or from a table. Traditionally data was copied between PostgreSQL and a file. However, recently a pretty cool feature was added to PostgreSQL: It is now possible […]