https://www.jackchristensen.com/ Recent content on <jack> Hugo -- gohugo.io en-us Sat, 26 Sep 2020 00:00:00 +0000 https://www.jackchristensen.com/2020/09/26/improving-sql-tests-with-doppelganger-and-canary-data.html Sat, 26 Sep 2020 00:00:00 +0000 https://www.jackchristensen.com/2020/09/26/improving-sql-tests-with-doppelganger-and-canary-data.html SQL statements can appear to work correctly in development and testing but fail catastrophically in production https://www.jackchristensen.com/2020/08/01/sharpening-the-axe.html Sat, 01 Aug 2020 00:00:00 +0000 https://www.jackchristensen.com/2020/08/01/sharpening-the-axe.html The ancients recognized the wisdom of sharpening one&rsquo;s tools. It is especially important in software development https://www.jackchristensen.com/2020/04/18/when-to-use-postgresql-enums.html Sat, 18 Apr 2020 00:00:00 +0000 https://www.jackchristensen.com/2020/04/18/when-to-use-postgresql-enums.html PostgreSQL enums should be used for values that directly impact application control flow. https://www.jackchristensen.com/2020/04/11/the-context-overridable-global-pattern-in-go.html Sat, 11 Apr 2020 00:00:00 +0000 https://www.jackchristensen.com/2020/04/11/the-context-overridable-global-pattern-in-go.html Contexts and global variables mitigate each others weakness. https://www.jackchristensen.com/2018/02/04/simple-enums-in-ruby-with-meta-enum.html Sun, 04 Feb 2018 00:00:00 +0000 https://www.jackchristensen.com/2018/02/04/simple-enums-in-ruby-with-meta-enum.html Ruby does not have a built-in enum type. The meta_enum gem can fill the gap. https://www.jackchristensen.com/2017/08/08/simple-postgresql-upgrades-in-development.html Tue, 08 Aug 2017 00:00:00 +0000 https://www.jackchristensen.com/2017/08/08/simple-postgresql-upgrades-in-development.html Upgrading a production PostgreSQL server can be a complex and delicate process. But in a development environment downtime is not an issue and database size is typically fairly small. For these cases performing the same upgrade process as production can be overkill. There is a simpler way. https://www.jackchristensen.com/2016/09/08/development-of-a-simple-command-line-websocket-client.html Thu, 08 Sep 2016 00:00:00 +0000 https://www.jackchristensen.com/2016/09/08/development-of-a-simple-command-line-websocket-client.html While working on the Websocket Shootout, I frequently needed to connect to a websocket server and interact directly. None of the existing tools I was aware of had exactly the features I was wanted. That led to the creation of ws. https://www.jackchristensen.com/2016/07/07/modeling-polymorphic-associations-in-a-relational-database.html Thu, 07 Jul 2016 00:00:00 +0000 https://www.jackchristensen.com/2016/07/07/modeling-polymorphic-associations-in-a-relational-database.html Polymorphic associations can be difficult to correctly represent in a relational database. In this post I will compare and contrast four different ways to model these challenging relationships. https://www.jackchristensen.com/2016/02/15/custom-aggregates-in-postgresql.html Mon, 15 Feb 2016 00:00:00 +0000 https://www.jackchristensen.com/2016/02/15/custom-aggregates-in-postgresql.html Given a bank account of debit and credit transactions, what is the greatest balance the account ever had? Given a hotel with arrivals and departures, what is the greatest number of guests the hotel ever had? Both of these are examples of finding the greatest running total. Finding the greatest running total is a great exercise with which to explore some of the lesser known features of PostgreSQL such as window functions, custom aggregates, and C functions. https://www.jackchristensen.com/2015/12/28/switch-vs-map-which-is-the-better-way-to-branch-in-go.html Mon, 28 Dec 2015 00:00:00 +0000 https://www.jackchristensen.com/2015/12/28/switch-vs-map-which-is-the-better-way-to-branch-in-go.html This article compares the performance of map lookup and switch statements in Go? https://www.jackchristensen.com/2015/04/23/materialized-view-strategies-using-postgresql.html Thu, 23 Apr 2015 00:00:00 +0000 https://www.jackchristensen.com/2015/04/23/materialized-view-strategies-using-postgresql.html Queries returning aggregate, summary, and computed data are frequently used in application development. Sometimes these queries are not fast enough. Caching query results using Memcached or Redis is a common approach for resolving these performance issues. However, these bring their own challenges. Before reaching for an external tool it is worth examining what techniques PostgreSQL offers for caching query results. https://www.jackchristensen.com/page/about.html Fri, 03 Apr 2015 02:13:50 +0000 https://www.jackchristensen.com/page/about.html About Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aenean nec dolor in magna lobortis egestas. Suspendisse eu erat tempor, tristique neque eu, convallis nulla. Curabitur vel bibendum lacus, at semper mauris. Suspendisse aliquet commodo ex, sed sagittis metus aliquam id. Maecenas feugiat rutrum lorem vel imperdiet. Nullam ornare lectus ut enim finibus, et porttitor mi tincidunt. Aenean lacinia, leo quis vehicula eleifend, quam libero sagittis erat, at euismod augue mauris et sapien. https://www.jackchristensen.com/page/contact.html Fri, 03 Apr 2015 02:13:50 +0000 https://www.jackchristensen.com/page/contact.html Contact Aenean ipsum justo, semper eu nisl ut, pretium tincidunt sem. Praesent et diam sit amet lacus lobortis dictum a id lacus. Quisque hendrerit sit amet turpis eu varius. Ut id lorem ac felis ultrices tincidunt. Pellentesque consequat arcu ac fringilla imperdiet. Phasellus pellentesque, sapien non pulvinar blandit, sapien ante aliquet felis, vel porttitor sapien ante in lacus. Fusce non urna aliquet, malesuada nibh vel, luctus urna. Phasellus ut lacus molestie, varius purus quis, malesuada lorem. https://www.jackchristensen.com/2014/12/18/16-tips-from-the-2014-winter-miniconf.html Thu, 18 Dec 2014 00:00:00 +0000 https://www.jackchristensen.com/2014/12/18/16-tips-from-the-2014-winter-miniconf.html Hashrocket hosts an internal conference twice a year called Miniconf where we take a day to share ideas with each other. This last Miniconf I gave a quick 20 minute talk with a grab bag of Linux, shell, PostgreSQL, and Ruby tricks. This article is that talk converted to text format. https://www.jackchristensen.com/2014/10/04/react2fs-react-to-file-system-changes.html Sat, 04 Oct 2014 00:00:00 +0000 https://www.jackchristensen.com/2014/10/04/react2fs-react-to-file-system-changes.html React to file system changes by executing a command https://www.jackchristensen.com/2014/08/07/go-performance-observations.html Thu, 07 Aug 2014 00:00:00 +0000 https://www.jackchristensen.com/2014/08/07/go-performance-observations.html In the course of optimizing the pgx PostgreSQL driver I observed a number of performance characteristics of Go that I hope you will find useful. https://www.jackchristensen.com/2014/04/19/tern-1-0-0-released.html Sat, 19 Apr 2014 00:00:00 +0000 https://www.jackchristensen.com/2014/04/19/tern-1-0-0-released.html New release of Tern rewritten in Go https://www.jackchristensen.com/2013/08/18/writable-common-table-expressions.html Sun, 18 Aug 2013 00:00:00 +0000 https://www.jackchristensen.com/2013/08/18/writable-common-table-expressions.html Writable common table expressions are a powerful feature of PostgreSQL that is rarely used when building applications with an ORM like ActiveRecord. It allows inserts, updates, and deletes to be performed in the WITH clause of an SQL statement. Here are a few techniques that I have found useful. https://www.jackchristensen.com/2013/02/22/surus-0-4-0-released.html Fri, 22 Feb 2013 00:00:00 +0000 https://www.jackchristensen.com/2013/02/22/surus-0-4-0-released.html Surus now can use PostgreSQL&rsquo;s JSON functions to build JSON much faster than Rails to_json https://www.jackchristensen.com/2013/01/29/faster-json-generation-with-postgresql.html Tue, 29 Jan 2013 00:00:00 +0000 https://www.jackchristensen.com/2013/01/29/faster-json-generation-with-postgresql.html A new feature in PostgreSQL 9.2 is JSON support. It includes a JSON data type and two JSON functions. These allow us to return JSON directly from the database server. This article covers how it is done and includes a benchmark comparing it with traditional Rails JSON generation techniques. https://www.jackchristensen.com/2012/08/25/text-tunnel-remote-text-editing.html Sat, 25 Aug 2012 00:00:00 +0000 https://www.jackchristensen.com/2012/08/25/text-tunnel-remote-text-editing.html Use your favorite GUI text editor on remote servers over SSH. https://www.jackchristensen.com/2012/02/16/surus-postgresql-extensions-for-active-record.html Thu, 16 Feb 2012 00:00:00 +0000 https://www.jackchristensen.com/2012/02/16/surus-postgresql-extensions-for-active-record.html Accelerate ActiveRecord with PostgreSQL specific support https://www.jackchristensen.com/2011/02/07/tern-the-sql-fans-migrator.html Mon, 07 Feb 2011 00:00:00 +0000 https://www.jackchristensen.com/2011/02/07/tern-the-sql-fans-migrator.html New gem to simplify complex database schema migrations https://www.jackchristensen.com/2010/11/29/tod-time-of-day-for-ruby.html Mon, 29 Nov 2010 00:00:00 +0000 https://www.jackchristensen.com/2010/11/29/tod-time-of-day-for-ruby.html New gem to simplify time of day handling https://www.jackchristensen.com/2009/11/14/assert-db-rejects-new-rails-test-plugin.html Sat, 14 Nov 2009 00:00:00 +0000 https://www.jackchristensen.com/2009/11/14/assert-db-rejects-new-rails-test-plugin.html A simple gem plugin for testing database constraints. https://www.jackchristensen.com/2009/08/08/solving-a-math-puzzle-with-ruby.html Sat, 08 Aug 2009 00:00:00 +0000 https://www.jackchristensen.com/2009/08/08/solving-a-math-puzzle-with-ruby.html A math puzzle from The Art of Game Design by Jesse Schell is solved with Ruby. https://www.jackchristensen.com/2009/07/11/linksys-wrt54g2-connection-problems-solved-by-dd-wrt.html Sat, 11 Jul 2009 00:00:00 +0000 https://www.jackchristensen.com/2009/07/11/linksys-wrt54g2-connection-problems-solved-by-dd-wrt.html Random internet connection loss was solved by installing DD-WRT. https://www.jackchristensen.com/2009/06/22/selenium-broken-by-firefox-upgrade-on-ubuntu.html Mon, 22 Jun 2009 00:00:00 +0000 https://www.jackchristensen.com/2009/06/22/selenium-broken-by-firefox-upgrade-on-ubuntu.html The path to the Firefox binary changes on upgrade. This can break Selenium. https://www.jackchristensen.com/2009/06/20/ruby-19-on-windows-7-virtualbox-and-ubuntu.html Sat, 20 Jun 2009 00:00:00 +0000 https://www.jackchristensen.com/2009/06/20/ruby-19-on-windows-7-virtualbox-and-ubuntu.html Ruby is more at home on *nix than on Windows. This tutorial covers setting up a Windows machine as a VM host, installing an Ubuntu VM, building Ruby 1.9, and setting up file sharing between Windows and the VM.