Managing connections in Postgres is a topic that seems to come up several times a week in conversations. I’ve written some about scaling your connections and the right approach when you truly need a high level of connections, which is to use a connection pooler like pgBouncer. But what do you do before that point and how can you better track what is going on with your connections in Postgres?
As your database grows and scales there are some operations that you need to take more care of than you did when you were just starting. When working with your application in your dev environment you may not be fully aware of the cost of some operations until you run them against production. And at some point most of us have been guilty of it, running some migration that starts at 5 minutes, then 15 minutes in it’s still running, and suddenly production traffic is impacted.
There are two operations that tend to happen quite frequently, each with some straightforward approaches to mitigate having any noticable amount of downtime. Let’s look at each of the operations, how they work and then how you can approach them in a safer way.
It’s not a very disputed topic that you should backup your database, and further test your backups. What is a little less discussed, at least for Postgres, is the types of backups that exist. Within Postgres there are two forms of backups and understanding them is a useful foundation for anyone working with Postgres. The two backup types are
Let’s dig into each a bit more so you can better assess which makes sense for you.
A massive amount of reporting queries, whether really intensive data analysis, or just basic insights into your business involving looking at data over a certain time period. Postgres has really rich support for dealing with time out of the box, something that’s often very underweighted when dealing with a database. Sure, if you have a time-series database it’s implied, but even then how flexible and friendly is it from a query perspective? With Postgres there’s a lot of key items available to you, let’s dig in at the things that make your life easier when querying.
JSONB is an awesome datatype in Postgres. I find myself using it on a weekly basis these days. Often in using some API (such as clearbit) I’ll get a JSON response back, instead of parsing that out into a table structure it’s really easy to throw it into a JSONB then query for various parts of it.
If you’re not familiar with JSONB, it’s a binary representation of JSON in your database. You can read a bit more about it vs. JSON here.
In working with JSONB here’s a few quick tips to get up and running with it even faster:
It seems each week when I’m reviewing data with someone a feature comes up that they had no idea existed within Postgres. In an effort to continue documenting many of the features and functionality that are useful, here’s a list of just a few that you may find handy the next time your working with your data.
This one I’ve covered before, but it’s worth restating. Psql is a great editor that already comes with Postgres. If you’re comfortable on the CLI you should consider giving it a try. You can even setup you’re own .psqlrc for it so that it’s well customized to your liking. In particular turning \timing on is especially useful. But even with all sorts of customization if you’re not aware that you can use your preferred editor by using \e then you’re missing out. This will allow you to open up the last run query, edit it, save–and then it’ll run for you. Vim, Emacs, even Sublime text works just take your pick by setting your $EDITOR variable.
For the second time now I’ve had to implement a system that syncs from my system of record into Salesforce.com, the first at Heroku and now at Citus Data. The case here is pretty simple, I have a software-as-a-service, B2B product. It’s a homegrown application in these cases in Ruby, but could be Python, .Net, any language of your choosing. The problem is I don’t want to have to be rebuilding my own CRM, reporting, etc. on top of all of my internal database. And as soon as you’re at some reasonable size (sales guy of 1 or more) you need to be able to provide insights on what’s in that system of record database to others.
While my tooling isn’t a full fledged product by any means, here’s a bit of how I’ve developed this process a few times over and some of the annoying bits of code to help get you started. In this post I’ll walk through some of the basic datatypes, then we’ll follow-up with the overall architecture and tweaks you need to make to Salesforce, and finally we’ll provide some example code to help you create this setup yourself.
SQL can be a powerful language for reporting. Whether you’re just exploring some data, or generating reports that show month over month revenue growth it’s the lingua franca for data analysis. But, your data isn’t always in a SQL database, even then if you’re using Postgres you can still likely use SQL to analyze, query, even joing with that data. Foreign data wrappers have been around for years in Postgres, but are continuing to mature and be a great option for joining disparate systems.
If you’re unfamiliar, foreign data wrappers, or FDW, allow you to connect from within Postgres to a remote system. Then you can query them from directly within Postgres. While there is an official Postgres FDW that ships with Postgres itself, that allows you to connect from one Postgres DB to another, there’s also a broad community of others.
At the core of it Postgres provides certain APIs under the covers which each FDW extension can implement. This can include the ability to map SQL to whatever makes sense for a given system, push down various operators like where clauses, and as of Postgres 9.3 can even write data.
When you start out as a developer there’s an overwhelming amount of things to grasp. First there’s the language itself, then all the quirks of the specific framework you’re using,and after that (or maybe before) we’ll throw front-end development into the mix, and somewhere along the line you have to decide to store your data somewhere.
Early on, with so many things to quickly master, the database tends to be an after-though in application design (perhaps because it doesn’t make an impact to end user experience). As a result there’s a number of bad practices that tend to get picked up when working with databases, here’s a rundown of just a few.