By Kirk Wolak Continuous Improvement is an important part of reducing technical debt. Over 30 years our active database has collected some technical debt. We wanted to rename all of our views to be consistently named. Besides that, we had a lack of code reviews for what is happening in the database. The latter situation […]
PostgreSQL uses shared memory for data shared between processes. With the exception of the dynamic shared memory segments used for exchanging data between parallel workers, the server allocates shared memory with a fixed size when it starts. But each PostgreSQL backend process also has to manage private memory to process SQL statements. In this […]
CLUSTER is sometimes the last resort to squeeze performance out of an index scan. Normally, you have to repeat CLUSTER regularly to maintain good performance. In this article, I will show you how you can get away without re-CLUSTERing even in the face of concurrent UPDATEs. Thanks to Steven Hulshof for the idea! Why […]
One way to organize data in PostgreSQL is to make use of schemas. What is a schema in PostgreSQL? And more importantly: What is the purpose of a schema and how can schemas be used to make your life easier? Let’s dive in and find out. The purpose of a schema Before you figure out […]
(Inscription seen on a T-shirt) It’s annoying to get error messages caused by encoding problems. But it is more annoying not to get error messages and end up with bad data in the database. I’ll show you how to fix bad encoding. Some basic facts about encoding in PostgreSQL Each PostgreSQL database has a server […]
Many people have heard that ALTER DEFAULT PRIVILEGES makes it easy to allow other users access to tables. But then, many people don’t understand the command in depth, and I hear frequent complaints that ALTER DEFAULT PRIVILEGES does not work as expected. Read on if you want to know better! Default privileges You cannot […]
Different from many other database systems, PostgreSQL does not support query hints. That makes it difficult to force the hand of the query planner when it comes to a certain join order that you know to be good. This article explains how you can influence execution plans in PostgreSQL. Why no query hints? The […]
This is a short war story from a customer problem. It serves as a warning that there are special considerations when running software in a Docker container. The problem description The customer is running PostgreSQL in Docker containers. They are not using the “official” image, but their own. Sometimes, under conditions of high load, […]
A while ago, I wrote about how difficult it is to get an execution plan for a parameterized query. The method suggested in that article works, but is still somewhat complicated. So I wrote a patch to support an EXPLAIN option GENERIC_PLAN, which provides native support for that. My patch got committed by Tom […]
The PostgreSQL documentation has some information about row locks. But typically, you cannot see them in pg_locks, and not everybody knows how they work and how to track and debug row locks. This article intends to give some insight into how PostgreSQL row locks work “under the hood”. Why are there four kinds of […]
I am on a spree! After writing about breaking your database and transaction ID wraparound, here I am writing about damage caused by CHECK constraints! Trust me, I don’t want to destroy PostgreSQL databases. It’s just that this Twitter message was brought to my attention and triggered memories of other reports about CHECK constraints […]
Stored procedures are a core concept which can be found in most relational database systems. They have proven to be useful in many areas and have been widely adopted by developers and DBA’s alike. Stored procedures basics In PostgreSQL stored procedures have been around for a number of years. The syntax of this important command […]
