PostgreSQL query optimization with CREATE STATISTICS is an important topic. Usually, the PostgreSQL optimizer (query planner) does an excellent job. This is not only true for OLTP but also for data warehousing. However, in some cases the optimizer simply lacks the information to do its job properly. One of these situations has to do with […]

So, you’re building the next unicorn startup and are thinking feverishly about a future-proof PostgreSQL architecture to house your bytes? My advice here, having seen dozens of hopelessly over-engineered / oversized solutions as a database consultant over the last 5 years, is short and blunt: Don’t overthink, and keep it simple on the database side! […]

I decided to start out this year by looking into my notes from last year and extracting from them a small set of Postgres tips for you. This might not be, strictly speaking, fresh news… but I guess the average RAM of tech workers is about 64KB or so nowadays, so some repetition might not […]

A few years ago, I wrote a short post on a similar topic; since then, I’ve often seen that the whole concept of suggesting to do more INSERT-s in critical parts of the code seems pretty strange to most customers. It’s even alien to those who are not new to databases in general. So I […]

If you read this blog post the new PostgreSQL version will be probably already officially released to the public for wider usage…but seems some eager DBA already installed the last week’s Release Candidate 1 and took it for a spin 😉 The “spin” though takes 3 days to run for my scripts, so that’s the […]

© Laurenz Albe 2020 HOT updates are not a new feature. They were introduced by commit 282d2a03dd in 2007 and first appeared in PostgreSQL 8.3. But since HOT is not covered by the PostgreSQL documentation (although there is a README.HOT in the source tree), it is not as widely known as it should be: Hence […]

© Laurenz Albe 2020 There are three join strategies in PostgreSQL that work quite differently. If PostgreSQL chooses the wrong strategy, query performance can suffer a lot. This article explains the join strategies, how you can support them with indexes, what can go wrong with them and how you can tune your joins for better […]

© Laurenz Albe 2020 A while ago, I wrote about B-tree improvements in v12. PostgreSQL v13, which will come out later this year, will feature index entry deduplication as an even more impressive improvement. So I thought it was time for a follow-up. Deduplication for B-tree indexes If the indexed keys for different table rows […]

© Laurenz Albe 2020 A frequently asked question in this big data world is whether it is better to store binary data inside or outside of a PostgreSQL database. Also, since PostgreSQL has two ways of storing binary data, which one is better? I decided to benchmark the available options to have some data points […]

© 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 2020 In my daily work, I see many databases with a bad setting for max_connections. There is little advice out there for setting this parameter correctly, even though it is vital for the health of a database. So I decided to write up something. What is max_connections? According to the documentation, max_connections […]

© Laurenz Albe 2020   Recently, while troubleshooting PostgreSQL performance problems, I ran into problems with subtransactions twice. So I thought this was a nice topic for another blog post. What are subtransactions? Everybody knows database transactions. In PostgreSQL, which is operating in autocommit mode, you have to start a transaction that spans multiple statements […]