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Column And Table Redefinition With Minimal Locking

TLDR: Note to future self… (1) Read this before you modify a table on a live PostgreSQL database. If you do it wrong then your app might totally hang. There is a right way to do it which avoids that. (2) Especially remember the lock_timeout step. Many blog posts around the ‘net are missing this and it’s very important.

Recently I was chatting with some PostgreSQL users (who, BTW, were doing rather large-scale cool stuff in PG) and they asked a question about making schema changes with minimal impact to the running application. They were specifically curious about changing a primary key from INT to BIGINT.  (Oh, you are making all your new PK fields BIGINT right?)

Column And Table Redefinition With Minimal Locking

TLDR: Note to future self… (1) Read this before you modify a table on a live PostgreSQL database. If you do it wrong then your app might totally hang. There is a right way to do it which avoids that. (2) Especially remember the lock_timeout step. Many blog posts around the ‘net are missing this and it’s very important.

Recently I was chatting with some PostgreSQL users (who, BTW, were doing rather large-scale cool stuff in PG) and they asked a question about making schema changes with minimal impact to the running application. They were specifically curious about changing a primary key from INT to BIGINT.  (Oh, you are making all your new PK fields BIGINT right?)

Column And Table Redefinition With Minimal Locking

TLDR: Note to future self… (1) Read this before you modify a table on a live PostgreSQL database. If you do it wrong then your app might totally hang. There is a right way to do it which avoids that. (2) Especially remember the lock_timeout step. Many blog posts around the ‘net are missing this and it’s very important.

Recently I was chatting with some PostgreSQL users (who, BTW, were doing rather large-scale cool stuff in PG) and they asked a question about making schema changes with minimal impact to the running application. They were specifically curious about changing a primary key from INT to BIGINT.  (Oh, you are making all your new PK fields BIGINT right?)

Oracle archivelog deletion policy

Here are my posts on the dbi-services blog about archivelog deletion policy.

The deletion policy on a dataguard configuration should be:
CONFIGURE ARCHIVELOG DELETION POLICY TO APPLIED ON ALL STANDBY;

for the site where you don’t backup. It can be the standby or the primary.

and:
CONFIGURE ARCHIVELOG DELETION POLICY TO APPLIED ON ALL STANDBY BACKED UP 1 TIMES TO DISK;

for the site where you do the backups. It can be the primary or the standby.

Some related posts:

This Week in PostgreSQL – May 31

Since last October I’ve been periodically writing up summaries of interesting content I see on the internet related to PostgreSQL (generally blog posts). My original motivation was just to learn more about PostgreSQL – but I’ve started sharing them with a few colleagues and received positive feedback.  Thought I’d try posting one of these digests here on the Ardent blog – who knows, maybe a few old readers will find it interesting? Here’s the update that I put together last week – let me know what you think!


Hello from California!

Part of my team is here in Palo Alto and I’m visiting for a few days this week. You know… for all the remote work I’ve done over the years, I still really value this in-person, face-to-face time. These little trips from Seattle to other locations where my teammates physically sit are important to me.

This Week in PostgreSQL – May 31

Since last October I’ve been periodically writing up summaries of interesting content I see on the internet related to PostgreSQL (generally blog posts). My original motivation was just to learn more about PostgreSQL – but I’ve started sharing them with a few colleagues and received positive feedback.  Thought I’d try posting one of these digests here on the Ardent blog – who knows, maybe a few old readers will find it interesting? Here’s the update that I put together last week – let me know what you think!


Hello from California!

Part of my team is here in Palo Alto and I’m visiting for a few days this week. You know… for all the remote work I’ve done over the years, I still really value this in-person, face-to-face time. These little trips from Seattle to other locations where my teammates physically sit are important to me.

This Week in PostgreSQL – May 31

Since last October I’ve been periodically writing up summaries of interesting content I see on the internet related to PostgreSQL (generally blog posts). My original motivation was just to learn more about PostgreSQL – but I’ve started sharing them with a few colleagues and received positive feedback.  Thought I’d try posting one of these digests here on the Ardent blog – who knows, maybe a few old readers will find it interesting? Here’s the update that I put together last week – let me know what you think!


Hello from California!

Part of my team is here in Palo Alto and I’m visiting for a few days this week. You know… for all the remote work I’ve done over the years, I still really value this in-person, face-to-face time. These little trips from Seattle to other locations where my teammates physically sit are important to me.

Be the Change You Want to See In the (Tech) World

The only thing that stays the same is change….

As the time flies by and the world turns, I often am jarred back to reality when I discover how the little things we do can have a larger impact on the world around us.

Flying back from Interop ITX and StarEast conferences last week, I was reminded of this.  While reading the latest copy of Wired , I came across a story on D-Tech High School.  This is the school that resides on the Oracle headquarters campus, in its own building(s). The story was interviewing different students to discuss how they were making an impact on the technical world and how STEM schools, like D-Tech were changing the future.  What struck me, was that the lead in picture and student interview was with a young woman I’d worked with two years earlier as part of the Oracle Education Foundation.

Broadening Your Audience

I spent this week speaking at two conferences that may not be familiar to my usual crowd:
Techwell StarEast Testing Conference in Orlando, FL
Interop ITX Data Conference in Las Vegas, NV

Duplicating a Database on ODA

Introduction

Every so often, we get a request to duplicate a database for one of our customers using an Oracle Database Appliance (ODA). The process for doing that is relatively straightforward, but there are a couple of nuances along the way so I thought I’d write it up as a blog post in case it’s of use to others. Obviously, I have obfuscated any customer-specific information to protect their identity.

Configuration

The first nuance is to understand what database is being used as the source for the clone. Generally, a request for cloning will be something like this:

“We are creating a new environment which needs a new database to be set up. Please copy P1_SRV_T and restore as P1_SRV_F”.