Crunchy Blog

Managing PostgreSQL

Upgrading PostgreSQL from 9.4 to 10.3 with pglogical

April 22, 2018

I recently helped a customer upgrade a PostgreSQL instance from 9.4 on RHEL to 10.x on Ubuntu. While it initially sounded daunting, the use of pglogical and some planning actually made it rather straightforward. While there’s nothing new or original in this post, I still felt compelled to write it up for anyone else that might find the info useful as an example in their own endeavors.

pglogical is a logical replication system implemented entirely as a PostgreSQL extension. Fully integrated, it requires no triggers or external programs. This makes it faster than Slony, Londiste, et al. It is also (roughly) the basis upon which logical replication in PostgreSQL 10 core is built.

PostgreSQL, Kubernetes, Containers

How to Perform Failover with the PostgreSQL Kubernetes Operator

April 10, 2018

Crunchy Data recently released version 2.6 of the PostgreSQL Kubernetes Operator, a powerful controller that follows the Kubernetes Operator pattern that enables users to provision and manage thousands of PostgreSQL databases at scale. We thought that we would demonstrate some of the features in this latest version over the next few weeks, which includes support for manual database failover, storage selection, node (or server) selection preference, and many goodies that make it easier to manage a large PostgreSQL cluster.


Fast CSV and JSON Ingestion in PostgreSQL with COPY

April 03, 2018

If you have been asked to provide a CSV that someone can open up in their favorite spreadsheet editor, chances are you have used the PostgreSQL COPY command. COPY has been around since the early open source releases of PostgreSQL back in the late 1990s and was designed to quickly get data in and out of PostgreSQL.

COPY is also incredibly helpful for ingesting data into a table, especially if you have a lot of it to ingest, and will generally outperform INSERT. Let’s explore a few ways to use COPY to load some data into a table.


PostgreSQL Containers, PostgreSQL, Docker, Containers

An Easy Recipe for Creating a PostgreSQL Cluster with Docker Swarm

March 27, 2018

One of the biggest benefits of running PostgreSQL is running your cluster in primary-replica setup for the purposes of high-availability or load balancing your read-only queries.  It is not necessarily simple to deploy a primary-replica setup out of the box, but by using modern containerization technology, we can greatly simplify the process.

In this article, I will demonstrate how to easily setup and deploy a PostgreSQL primary-replica cluster using Docker and Docker Swarm.

PostgreSQL, security

Demystifying Schemas & search_path through Examples

March 02, 2018

On March 1, 2018, the PostgreSQL community released version 10.3 and other supported versions of PostgreSQL.  The release centered around a disclosed security vulnerability designated CVE-2018-1058, which is related to how a user can accidentally or maliciously "create like-named objects in different schemas that can change the behavior of other users' queries."

The PostgreSQL community released a guide around what exactly CVE-2018-1058 is and how to protect your databases. However, we thought it would also be helpful to look into what schemas are in PostgreSQL, how they are used under normal operations, and how to investigate your schemas to look for and eliminate suspicious functions.


Range Types & Recursion: How to Search Availability with PostgreSQL

February 22, 2018

One of the many reasons that PostgreSQL is fun to develop with is its robust collection of data types, such as the range type. Range types were introduced in PostgreSQL 9.2 with out-of-the-box support for numeric (integers, numerics) and temporal ranges (dates, timestamps), with infrastructure in place to create ranges of other data types (e.g. inet/cidr type ranges). Range data is found in many applications, from science to finance, and being able to efficiently compare ranges in PostgreSQL can take the onus off of applications workloads.

PostgreSQL, security

A PostgreSQL Row Level Security Primer + Creating Large Policies

February 12, 2018

Row Level Security, aka "RLS," allows a database administrator to define if a user should be able to view or manipulate specific rows of data within a table according to a policy. Introduced in PostgreSQL 9.5, row level security added another layer of security for PostgreSQL users who have additional security and compliance considerations for their applications.

At Crunchy Data, we care a lot about data security and supporting PostgreSQL. When we discovered an issue with creating a large row level security policy, we worked to find a workaround that provided a secure outcome but avoided creating a custom fork of PostgreSQL.  As of the publication of this post, the Crunchy Data team is working to address the issue with a patch that will be submitted for inclusion upstream.

To understand the issue and how our team found a solution, I'll first give a quick primer of how row level security works in PostgreSQL.

PostgreSQL, pgAdmin4, Docker, Containers

Easy PostgreSQL 10 and pgAdmin 4 Setup with Docker

February 05, 2018

The open source software ecosystem around PostgreSQL is as robust as the database itself, but sometimes it can be hard for people new to PostgreSQL, and even some seasoned veterans, to get all of the software dependencies for their development environment setup on their computers.

At Crunchy Data, we obsess  on making things as easy as possible for people to get software up and running, regardless of the technology. While I was trying to find things to experiment with using Docker, one of our engineers gave me a recipe to setup PostgreSQL 10 and pgAdmin 4 easily and quickly.  It was so simple, I thought it would be fun to share it!

PostgreSQL, bloat, index, pgstattuple

Checking for PostgreSQL Bloat

September 25, 2017

Crunchy Data is pleased to announce the welcome addition of Keith Fiske to our team.  Keith is a well known expert on the topic of bloat in PostgreSQL, and Crunchy Data felt there was no better way to announce his arrival that to share a post from Keith on the subject.

Analytics, PL/R, postgis

Using R Analytic Functions in PostGIS

April 25, 2017

This is the third and final post of the series intended to introduce PostgreSQL users to PL/R, a loadable procedural language that enables a user to write user-defined SQL functions in the R programming language. The information below provides sample use of R Functions against the NDVI dataset.