Posts

Sequential UUID Generators on SSD

After I shared the sequential UUID benchmarks a couple of weeks ago, one of the points raised in feedback was the choice of the storage space. I’ve intentionally used a fairly weak storage system (RAID10 on three 7.2k SATA drives) because I wanted to demonstrate the benefits. But a couple of readers suggested using SSDs might significantly reduce […]

On Rocks and Sand

When working with database capacity planning, there are a lot of variables to consider, and Postgres is no different in this regard. One of the elements which requires management is storage. However, there’s an aspect of storage that escapes inspection almost without exception, and it’s hiding in the shadows between the columns themselves. Alignment Basics […]

PostgreSQL Meltdown Benchmarks

Two serious security vulnerabilities (code named Meltdown and Spectre) were revealed a couple of weeks ago. Initial tests suggested the performance impact of mitigations (added in the kernel) might be up to ~30% for some workloads, depending on the syscall rate. Those early estimates had to be done quickly, and so were based on limited […]

PostgreSQL Meltdown

Spectre and Meltdown have caused severe alarm in recent days. You may have read about up to 30% impact on PostgreSQL databases, which I believe to be overstated because of misunderstandings in the media. Let’s dig into this in more detail. TL;DR Summary: no PostgreSQL patch required, -7% performance hit In response to these new […]

Benchmark on a Parallel Processing Monster!

Last year I wrote about a benchmark which I performed on the Parallel Aggregate feature that I worked on for PostgreSQL 9.6.  I was pretty excited to see this code finally ship in September last year, however something stood out on the release announcement that I didn’t quite understand: Scale Up with Parallel Query Version 9.6 […]

Basics of Tuning Checkpoints

On systems doing non-trivial number of writes, tuning checkpoints is crucial for getting good performance. Yet checkpoints are one of the areas where we often identify confusion and configuration issues, both on the community mailing lists and during performance tuning reviews for our customers. (The other one being autovacuum, discussed a few days ago by […]

Postgres-XL Scalability for Loading Data

In my last blog, we looked at the benchmark results from bulk load test for a Postgres-XL database cluster. Using a 16-datanode, 2-coordinator cluster, running on EC2 instances, we could easily clock 9M rows/sec or 3TB/hr of ingestion rate. That’s a significant number in itself. In this blog, we’ll see if the ingestion rate is […]

Load data in Postgres-XL at over 9M rows/sec

We are faced with this question: “What’s the ingestion rate of Postgres-XL?”, and I realised I don’t have a very good answer to that. Since recently we made some good improvements in this area, I was curious to know too. Well, I decided to benchmark. Hardware and Software For the tests, I used a Postgres-XL cluster running […]

Evolution of Fault Tolerance in PostgreSQL: Synchronous Commit

PostgreSQL is an awesome project and it evolves at an amazing rate. We’ll focus on evolution of fault tolerance capabilities in PostgreSQL throughout its versions with a series of blog posts. This is the fourth post of the series and we’ll talk about synchronous commit and its effects on fault tolerance and dependability of PostgreSQL. […]

PostgreSQL vs. Linux kernel versions

I’ve published multiple benchmarks comparing different PostgreSQL versions, as for example the performance archaeology talk (evaluating PostgreSQL 7.4 up to 9.4), and all those benchmark assumed fixed environment (hardware, kernel, …). Which is fine in many cases (e.g. when evaluating performance impact of a patch), but on production those things do change over time – […]