In PostgreSQL version 10 or less, if you add a new column to a table without specifying a default value then no change is made to the actual values stored. Any existing row will just fill in a NULL for that column. But if you specify a default value, the entire table gets rewritten with the default value filled in on every row. That rewriting behavior changes in PostgreSQL 11.
In a new feature I worked on and committed, the default value is just stored in the catalog and used where needed in rows existing at the time the change was made. New rows, and new versions of existing rows, are written with the default value in place, as happens now. Any row that doesn't have that column must have existed before the table change was made, and uses this value stored in the catalog when the row is (more…)
PostgreSQL 11, the next major release of the world’s most advanced open source database, is just around the corner. The new release of PostgreSQL will include enhancements in partitioning, parallelism, SQL stored procedures and much more.
To give PostgreSQL enthusiasts a deeper look into the upcoming release, 2ndQuadrant hosted a Webinar discussing the new features in PostgreSQL 11. The webinar was presented by Peter Eisentraut, Core Team Member and Major PostgreSQL Contributor.
If you weren’t able to make it to the live session, you can now view the recording here.
Questions that Peter couldn’t respond to during the live webinar have been answered below.
Q: Could you use a custom hash function for partitioning? (or is this in future plans)
A: This is currently not (more…)
We seldom credit patch reviewers. I decided to pay a little homage to those silent heroes for a few of them: here's the list of people who were credited as having reviewed the patches mentioned in my previous article for PostgreSQL 11. The number in front is the number of times they were credited as reviewers.
Amit Langote, Robert Haas
Dilip Kumar, Jesper Pedersen, Rajkumar Raghuwanshi
Amul Sul, David Rowley, Rafia Sabih, Simon Riggs, Thomas Munro
Antonin Houska, Ashutosh Bapat, Kyotaro Horiguchi
Álvaro Herrera, Amit Kapila, Amit Khandekar, Etsuro Fujita, Jaime Casanova, Keith Fiske, Konstantin Knizhnik, Pascal Legrand, Pavan Deolasee, Rajkumar Raghuanshi, Rushabh Lathia, Sven Kunze, Thom Brown, Yugo Nagata (more…)
A partitioning system in PostgreSQL was first added in PostgreSQL 8.1 by 2ndQuadrant founder Simon Riggs. It was based on relation inheritance and used a novel technique to exclude tables from being scanned by a query, called “constraint exclusion”. While it was a huge step forward at the time, it is nowadays seen as cumbersome to use as well as slow, and thus needing replacement.
In version 10, it was replaced thanks to heroic efforts by Amit Langote with modern-style “declarative partitioning”. This new tech meant you no longer needed to write code manually to route tuples to their correct partitions, and no longer needed to manually declare correct constraints for each partition: the system did those things automatically for you.
Sadly, in PostgreSQL 10 that's pretty much (more…)
About a year ago, we published PostgreSQL 10 with support for native logical replication. One of the uses of logical replication is to allow low- or no-downtime upgrading between PostgreSQL major versions. Until now, PostgreSQL 10 was the only PostgreSQL release with native logical replication, so there weren't many opportunities for upgrading in this way. (Logical replication can also be used for moving data between instances on different operating systems or CPU architectures or with different low-level configuration settings such as block size or locale -- sidegrading if you will.) Now that PostgreSQL 11 is near, there will be more reasons to make use of this functionality.
Let's first compare the three main ways to upgrade a PostgreSQL installation:
pg_dump and (more…)
Fans of Rapid Application Development (RAD!) are probably already familiar with Docker, but what does that have to do with Postgres? Database-driven applications are a dime a dozen these days, and a good RAD environment is something of a Holy Grail to coders and QA departments alike. Docker lets us spin up a Postgres instance in seconds, and discard it with a clean conscience.
There have even been some noises within certain circles about using it in a production context. Can we do something like that responsibly? Docker containers are practically guaranteed to be ephemeral, while production data most decidedly isn't. The answer to this is ultimately complex, and something we'll be exploring over the next several weeks.
Let's get started.
Let There Be Light
Since Docker itself is a (more…)
The short answer … Hell Yeah!
The long answer lies in extensive improvements and the impressive new feature list that makes up this major release - which, by the way, changes the version scheme of PostgreSQL as well (more details on that here). This wiki page lists out, in detail, all the new features in PostgreSQL 10, but for the purpose of this blog, I will focus on some of the exciting features contributed by 2ndQuadrant. (more…)
PostgreSQL 10 offers an exciting new set of features in addition to making further improvements to many of the already existing features including Big Data, Replication and Scaling, Administration, SQL, XML and JSON, Security, Performance and a lot more.
If you are planning to try your hands at PostgreSQL 10 and wondering on how you can easily get it on your machine, 2ndQuadrant’s GUI installers 2UDA can help you with an easier installation of PostgreSQL 10 for Windows, OS X and Linux platforms.
2ndQuadrant is a Platinum Sponsor of the PostgreSQL project and is committed to following community timelines for all releases; major & minor. This ensures that 2UDA releases are always up to date and available in a timely manner. With 2UDA's builtin upgrade feature for minor releases, it (more…)
Postgres-BDR (or just BDR, for short) is an open source project from 2ndQuadrant that provides multi-master features for PostgreSQL.
Here we will show how to build a test environment to play with BDR and how to configure it using the OmniDB 2.1 web interface.
2. Building test environment
Let's build a 2-node test environment to illustrate how to configure BDR within OmniDB.
2.1. Pull OmniDB repo
The first thing you need to do is to download OmniDB repo from GitHub and make sure you are in the development branch. Run the following:
git clone https://github.com/OmniDB/OmniDB
git checkout dev
2.2. Create 2 virtual machines with BDR
On your host machine, you need to have installed:
Vagrant plugin (more…)
One feature quietly added to PostgreSQL 10 is the ability to determine the commit status of any transaction by transaction-id.
It's reasonable to wonder why you'd want this, since you know if you committed the transaction, it's still in progress, or if you or rolled it back. And you can check for in-progress transactions in pg_stat_activity.
It exists to help the application recover to a known state after a failure without having to use heavyweight two-phase commit. It's also useful for querying standbys.
Imagine that your application has just sent the COMMIT for a transaction that's part of a queue processing system. Before the application receives a reply to its commit request, the database connection breaks due to network issues, a database crash, etc. It's possible (more…)