© 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 […]

Reserve connections for the pg_use_reserved_connections group in PostgreSQL 16 Nathan Bossart implemented a brand-new patch that provides a way to reserve connection slots for non-superusers. The patch was reviewed by Tushar Ahuja and Robert Haas. Committed by Robert Haas. The commit message is: Let’s try reserve connections in our work! Let’s edit the postgresql.conf file […]

© 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 […]

usql? But why? usql is a universal command-line interface for many database. But why are we still using CLI (command line utilities) in the 21st century? And what is wrong with psql? Despite the widespread availability and ease of use of GUI-based tools, many people still prefer to use command line utilities for a number […]

SQL and integer notations NEW in PostgreSQL 16 – support for non-decimal notation of integer constants! PostgreSQL already has powerful support for string constants, with E’\t’, E’\011′, E’\u0009′ and U&’\0009′ all meaning the same thing (a “horizontal tab” character). However, PostgreSQL’s support for numerical constants has – up until now – been rather limited; it […]

What is pg_dump compression? pg_dump is a PostgreSQL utility for backing up a local or remote PostgreSQL database. It creates a logical backup file that contains either plain SQL commands for recreating the database, or a binary file that can be restored with the pg_restore utility. The binary backup file can be used to restore […]

What is GRANT VACUUM, ANALYZE? PostgreSQL uses table VACUUM and ANALYZE commands to optimize the database. The VACUUM command reclaims storage space and makes it available for re-use. It also updates the visibility map, which helps the query planner to quickly identify which parts of the table have live rows. The ANALYZE command collects statistics […]

In PostgreSQL 15, a fundamental change took place which is relevant to every user who happens to work with permissions: The default permissions of the public schema have been modified. This is relevant because it might hurt you during application deployment. You need to be aware of how it may affect you. Creating users Many […]

Rewriting OR is not always the best solution © Laurenz Albe 2022 In my article that reviles OR, I showed how in certain cases, it is possible to rewrite OR in a WHERE condition to a longer query with UNION that can perform much better (the “ugly” OR). Now people have asked me repeatedly why […]

It’s been many years since the first ideas to implement the MERGE command surfaced on the PostgreSQL mailing list. Now this important feature has finally made it into PostgreSQL core, in PostgreSQL 15. To show people how this vital command works, I have decided to come up with a technical preview to introduce my readers […]

Understanding Multiranges Range types have been around in PostgreSQL for quite some time and are successfully used by developers to store various kinds of intervals with upper and lower bounds. However, in PostgreSQL 14 a major new feature has been added to the database which makes this feature even more powerful: multiranges. To help you […]

We want to announce that the beta release of pgwatch2 v1.9 is now available for download. This release contains previews of all features that will be available in the final release of pgwatch2 v1.9, though some details of the release could change before then. You can find information about all of the new features and […]