(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 […]
© Laurenz Albe 2023 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 […]
© Laurenz Albe 2023 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 […]
© Laurenz Albe 2023 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 […]
© Laurenz Albe 2023 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 […]
© Laurenz Albe 2023 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 […]
© Laurenz Albe 2023 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 […]
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 […]
PostgreSQL provides all kinds of time-related functions. But time is not as easy as it seems. One question many people keep asking: How can I find the current timestamp? What time is it? While this seems like an easy question the answer isn’t as clear-cut as you might expect. Basically, there are three functions we […]
© Laurenz Albe 2022 Most people are aware of transaction ID wraparound. The concept has been well explained in Hans’ article, so I won’t repeat all that here. But for most people it is an abstract concept, a bogeyman lurking in the dark around the corner. Many people know horror stories about anti-wraparound autovacuum tanking […]
© Laurenz Albe 2022 I have been faced with a request for an unusual unique constraint that puzzled me for a while. Since the solution I came up with is a nice show-case for range data types, I’ll share it with you. Also, it allows me to rant some about NULL, which is a temptation […]
© Laurenz Albe 2022 When processing a big result set in an interactive application, you want to paginate the result set, that is, show it page by page. Everybody is familiar with that from the first web search on. You also get a button to scroll to the next page, and you get a total […]
