This is a post about Datalevin, an open-source database system that I have been building since 2020. Although JOB here is really an acronym for Join Order Benchmark, a benchmark for complex database queries, I intend to build up Datalevin to compete for the same kind of jobs usually held …

Someone asked on Reddit: Why Clojure is not widely adopted like mainstream languages?

Here's my answer:

You probably should have flipped the question, because the vast majority of programming languages are not mainstream.

The more insightful question is: "Why and how did a language X become mainstream?"

From the answers …

Here is the story. I am adding full-text search capability to Datalevin, a Datalog database that we open sourced last year. For this task, I have decided to write a search engine from scratch instead of using an existing search library. Here are some rationales for this decision. Today I …

Recently, I upgraded the FreeIPA server for my network to the latest version (4.8.10). Some strange things related to authentication started to happen with some services on my network.

For our Web site, netlify gotrue is used to enable users to login using SAML Single Sign-On. This started …

Someone asked on Reddit this question, for he's wondering if it is worth the time to learn Clojure well. He has dabbled in Clojure for half a year, but was not convinced of its benefits. He has not used REPL much, and was wondering if he was doing something wrong …

One of the latest fashions in the Java world is GraalVM. For someone who has been around, I still remember the "Write once, run anywhere" slogan of Java virtual machine. Apparently, the wheel has spun back, now people want to write native code in Java, which has to be compiled …

For a public facing Web interface of FreeIPA server, it is desirable to use a 3rd party SSL certificate issued by a commonly accepted certificate authority, rather than using the server's own. Let's Encrypt provides free SSL certificate for this purpose.

To use Letsencrypt certificate with FreeIPA, this script does …

The main product of my startup is written in Clojure, a language that puts enormous pressure on the memory garbage collector due to the pervasive use of immutable data structures. The new Z garbage collector on JVM has been a blessing for us, as it has largely solved our memory …

With newer versions of on-premise Sentry (I am using Sentry 20.10.1), the LDAP authentication does not seem to work any more. The code still compiles but the LDAP login UI does not show up. Fortunately, newer versions of Sentry provide built-in support for SAML2 authentication, so we can …

To control access to various internal Web sites of a company, a simple method is to enable LDAP authentication on the Web server, so that the company directory can be brought to bear and there is no need to create individual accounts for employees on different systems.

Nginx is one …

If you are using a self-hosted Netlify CMS as the online editor for your SSG powered Website and you are using the editorial workflow (you have publish_mode: editorial_workflow in your config.yml), a pain point is that you do not see a preview of the live page when the page …

Static Site Generator (SSG) is in vogue for building Web sites. Compared with traditional content management system (CMS), SSG is more performant, flexible and easier to maintain for people comfortable with coding . However, for the non-technical crowd, a WYSIWYG online editor is still the way to go. Netlify CMS fills …

This blog has undergone a few migrations over its 15 years life span.

It started out as a Blogger account in 2005. The purpose was to record some system administration details when I was an assistant professor at university, setting up my laboratry for students.

Then Yunyao joined in after …

DokuWiki is one of the most easy-to-use open source Wiki software. It is a very good internal documentation tool for small or medium sized organizations.

Comparing with using Google Docs for the same purpose, one advantage of using a Wiki is that it is more searchable and navigable. In addition …

Discourse is a modern forum software that is quite popular in the technology circle. One can install a Discourse server easily with the recommended method of using docker. All the services needed by the Discourse server, e.g. Postgresql and Redis, will be running inside a docker container, which is …

Sentry is a fairly popular service for tracking exceptions and errors in production softwares. They also provides a docker recipe for people who want to self host their own sentry server. This post shows how to enable LDAP authentication for such a self hosted sentry server, using freeIPA as the …

The point of setting up freeIPA for an intranet is to enable single-sign-on (SSO) for all the internal services that requires authentication and authorization. LDAP, originated from my alma mater University of Michigan, is one of the most widely accepted solutions to the problem. freeIPA can serve as a LDAP …

FreeIPA is the open source version of RedHat's identity management solution, which nicely integrates several open sources services that are important for managing an intranet: 389 LDAP Directory Server, MIT Kerboros, NTP, DNS, SSSD and others. 

Most of my servers are virtual machines in AWS EC2. To manage such a …

As part of our house modernization process, we bought an Ecobee3 Wifi enabled smart thermostat. We hope that this small device will help reduce the size of our utility bill.  The product looks very simple, but it comes with three additional sensors that can be placed in different rooms, and …

Since Drupal 6 is no longer supported, I upgraded this site to the lasted version of Drupal 8.4.2 by following the guide. As you can see, the upgrade mostly worked. However, there are a few points of caution as well as some unresolved problems.

As before, I setup …