2ndQuadrant is now part of EDB

Bringing together some of the world's top PostgreSQL experts.

2ndQuadrant | PostgreSQL
Mission Critical Databases
  • Contact us
  • EN
    • FR
    • IT
    • ES
    • DE
    • PT
  • Support & Services
  • Products
  • Downloads
    • Installers
      • Postgres Installer
      • 2UDA – Unified Data Analytics
    • Whitepapers
      • Business Case for PostgreSQL Support
      • Security Best Practices for PostgreSQL
    • Case Studies
      • Performance Tuning
        • BenchPrep
        • tastyworks
      • Distributed Clusters
        • ClickUp
        • European Space Agency (ESA)
        • Telefónica del Sur
        • Animal Logic
      • Database Administration
        • Agilis Systems
      • Professional Training
        • Met Office
        • London & Partners
      • Database Upgrades
        • Alfred Wegener Institute (AWI)
      • Database Migration
        • International Game Technology (IGT)
        • Healthcare Software Solutions (HSS)
        • Navionics
  • Postgres Learning Center
    • Webinars
      • Upcoming Webinars
      • Webinar Library
    • Whitepapers
      • Business Case for PostgreSQL Support
      • Security Best Practices for PostgreSQL
    • Blog
    • Training
      • Course Catalogue
    • Case Studies
      • Performance Tuning
        • BenchPrep
        • tastyworks
      • Distributed Clusters
        • ClickUp
        • European Space Agency (ESA)
        • Telefónica del Sur
        • Animal Logic
      • Database Administration
        • Agilis Systems
      • Professional Training
        • Met Office
        • London & Partners
      • Database Upgrades
        • Alfred Wegener Institute (AWI)
      • Database Migration
        • International Game Technology (IGT)
        • Healthcare Software Solutions (HSS)
        • Navionics
    • Books
      • PostgreSQL 11 Administration Cookbook
      • PostgreSQL 10 Administration Cookbook
      • PostgreSQL High Availability Cookbook – 2nd Edition
      • PostgreSQL 9 Administration Cookbook – 3rd Edition
      • PostgreSQL Server Programming Cookbook – 2nd Edition
      • PostgreSQL 9 Cookbook – Chinese Edition
    • Videos
    • Events
    • PostgreSQL
      • PostgreSQL – History
      • Who uses PostgreSQL?
      • PostgreSQL FAQ
      • PostgreSQL vs MySQL
      • The Business Case for PostgreSQL
      • Security Information
      • Documentation
  • About Us
    • About 2ndQuadrant
    • 2ndQuadrant’s Passion for PostgreSQL
    • News
    • Careers
    • Team Profile
  • Blog
  • Menu Menu
You are here: Home1 / Blog2 / Webinars3 / Webinar: Identity Columns and Generated Columns in PostgreSQL [Follow ...
Identity Columns and Generated Columns in PostgreSQL
Bilal Ibrar

Webinar: Identity Columns and Generated Columns in PostgreSQL [Follow Up]

April 6, 2020/0 Comments/in Webinars /by Bilal Ibrar

Identity Columns, initially rolled out in PostgreSQL 10, offer a standard-conforming and robust way to dynamically create auto-incrementing fields in tables. 

Generated Columns, computed from other columns, were first introduced in PostgreSQL 12. They enable more flexible schema design and performance benefits for your database. 

To cover the topic of “Identity Columns and Generated Columns in PostgreSQL” in more detail, 2ndQuadrant held a live webinar, hosted by Peter Eisentraut (CTO, 2ndQuadrant).

This webinar explored the different types of column methods with a focus on real-world use cases and detailed the difference between “generated always as identity” and “generated by default as identity” in PostgreSQL 12.

Those who weren’t able to attend the live webinar, can now view the recording here.

Due to limited time, some of the questions asked online were not answered during the live webinar; Peter’s replies are provided below:


Question: When you use override and insert value for identity, how does that affect the implicit sequence value?

Answer: The sequence is not changed if you use OVERRIDING SYSTEM VALUE. It is the user’s responsibility to make sure that manually inserted values do not conflict with current or future sequence values.

 

Question: Insert into tables overriding system value.. Can that be used to reset the next sequence value?

Answer: No, this does not change the sequence value. To change the sequence value, you can use the usual PostgreSQL function setval().

 

Question: Generated columns are computed again when updating a row *even when the base columns haven’t changed*. That’s inefficient and not negligible when the calculation is expensive.

Answer: This has been improved in PostgreSQL 13.

 

Question: How can I change an identity column to a bigger data type?

Answer: You can use the usual ALTER TABLE … ALTER COLUMN … TYPE command. This will also update the associated sequence accordingly. However, this command will lock and rewrite the table. To do this without extensive downtime requires custom techniques, such as copying the values into a new table gradually, perhaps using triggers or replication techniques. Therefore, it is recommended to plan the appropriate data type when the table is created.


To stay updated on upcoming webinars by 2ndQuadrant, you can visit our Webinars page.

For any questions, comments, or feedback, please visit our website or send an email to [email protected].

Tags: PostgreSQL, webinars
Share this entry
  • Share on Facebook
  • Share on Twitter
  • Share on WhatsApp
  • Share on LinkedIn
0 replies

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Search

Get in touch with us!

Recent Posts

  • Random Data December 3, 2020
  • Webinar: COMMIT Without Fear – The Beauty of CAMO [Follow Up] November 13, 2020
  • Full-text search since PostgreSQL 8.3 November 5, 2020
  • Random numbers November 3, 2020
  • Webinar: Best Practices for Bulk Data Loading in PostgreSQL [Follow Up] November 2, 2020

Featured External Blogs

Tomas Vondra's Blog

Our Bloggers

  • Simon Riggs
  • Alvaro Herrera
  • Andrew Dunstan
  • Craig Ringer
  • Francesco Canovai
  • Gabriele Bartolini
  • Giulio Calacoci
  • Ian Barwick
  • Marco Nenciarini
  • Mark Wong
  • Pavan Deolasee
  • Petr Jelinek
  • Shaun Thomas
  • Tomas Vondra
  • Umair Shahid

PostgreSQL Cloud

2QLovesPG 2UDA 9.6 backup Barman BDR Business Continuity community conference database DBA development devops disaster recovery greenplum Hot Standby JSON JSONB logical replication monitoring OmniDB open source Orange performance PG12 pgbarman pglogical PG Phriday postgres Postgres-BDR postgres-xl PostgreSQL PostgreSQL 9.6 PostgreSQL10 PostgreSQL11 PostgreSQL 11 PostgreSQL 11 New Features postgresql repmgr Recovery replication security sql wal webinar webinars

Support & Services

24/7 Production Support

Developer Support

Remote DBA for PostgreSQL

PostgreSQL Database Monitoring

PostgreSQL Health Check

PostgreSQL Performance Tuning

Database Security Audit

Upgrade PostgreSQL

PostgreSQL Migration Assessment

Migrate from Oracle to PostgreSQL

Products

HA Postgres Clusters

Postgres-BDR®

2ndQPostgres

pglogical

repmgr

Barman

Postgres Cloud Manager

SQL Firewall

Postgres-XL

OmniDB

Postgres Installer

2UDA

Postgres Learning Center

Introducing Postgres

Blog

Webinars

Books

Videos

Training

Case Studies

Events

About Us

About 2ndQuadrant

What does 2ndQuadrant Mean?

News

Careers 

Team Profile

© 2ndQuadrant Ltd. All rights reserved. | Privacy Policy
  • Twitter
  • LinkedIn
  • Facebook
  • Youtube
  • Mail
Developing PostgreSQL for Windows, Part 3 Developing PostgreSQL for Windows - Part 3 How to use the Random Forest Machine Learning Model with 2UDA – PostgreSQL...
Scroll to top
×