TIL

Today I learned that postgres allows you to use a subselect in an update statement using a special syntax. This allows you to update a record from other data in the system easily (without remembering the weird update-with-join syntax) or to have an update syntax that more closely resembles an insert statement. For example:

UPDATE table
SET (foo, bar) =
(SELECT 'foo', 'bar')
WHERE id = 1;

The subselect can be any query, just return your columns in the same order as the column list you provide. Here is the relevant documentation if you want to read further: https://www.postgresql.org/docs/current/static/sql-update.html

There are few things I have learned in my programming career that have paid off like higher order functions. Map, Reduce and Filter with their cousins, along with the concept of passing functions as data in general make code easier to reason about, easier to write, easier to test. I find myself evangelizing these concepts often, so I thought I would try to do my best to give an introduction of them, along with some real world examples of how they can improve your everyday programming life. These examples are in JavaScript, but the concepts are universal.

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At MotorsportReg we have customers all over the world so there is never a good time for maintenance or downtime. Historically, we used multiple application servers with sticky CFML sessions on the load balancer. Deploying code often meant interrupting users to deploy changes which is unacceptable. We needed more flexibility.

Sidecar is our solution, an external session management plugin for ColdFusion. Inspired by sessions in expressjs, we separated the persistence from the session management itself so you can plug in your favorite tech to fill that need - we wrote redis_session_store.cfc for our own needs, but all you have to do is implement the simple API for your preferred backend (memcached, couchdb, database, etc). If you implement your own storage adapter, please get in touch!

Once you have the potential for multiple servers to access session data at the same time, you’ll realize that <cflock> no longer offers the expected protection. We also wrote a separate distributed locking library, cfml-redlock, to make concurrent access safer, click here for some more info on that project).

This software is used in production. We wanted to open source it so that others can benefit but, also, selfishly in the hope that other companies will test it, file issues, or contribute. Implementation is simple - take a look at the tests and you should be able to get around pretty quickly. We plan to support Adobe ColdFusion 10+ and Lucee 4.5+ with this library.

If you have a passion for speed or love cars, motorcycles or karts, check out MotorsportReg. We have more than 5,000 track days, autocross, races and tours you can get involved with - chances are there is something happening near you!

During the development of Sidecar, an external session management plugin for ColdFusion, we selected Redis as our storage backend to support sessions in a cluster. Without relying on sticky sessions, we quickly realized that we needed a way to ensure that we wouldn’t step on our own toes as multiple servers potentially tried to access and modify session data concurrently.

After some research we decided on redlock for a distributed lock. This project is a port of node-redlock to CFML. It is useful outside of session management for any scenario where multiple servers need to run a process with transaction semantics so we have released it as its own library. About the time we finished development, Ben Nadel released his version of redlock. They’re similar but have a different API so check it out as well.

The goal is to support Adobe ColdFusion 10+ and Lucee 4.5+ with this library - like sidecar we are using these libraries in production, so we hope you find them useful and if welcome any contributions, including code, documentation or just reporting issues.

Want to build your own URL shortener? Have a bunch of sequential ID’s but don’t want it to be obvious what the next or previous in the sequence is? Base62 might be a good fit. Instead of 10 possible characters per digit you have 62, compressing the size of your identifier. Plus with a custom alphabet order, the next number in the sequence isn’t easily apparent. I have open sourced a CFML library that allows you to convert between base 10 and 62 here: https://github.com/ryanguill/cfmlBase62 - it supports custom alphabets (will also help generate one for you) and supports integers between 0 and 2⁶³-1 (9,223,372,036,854,775,807) so it can probably handle all of the nine quintillion identifiers in your database.

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