daniela

daniela

High Performance PostgreSQL for Rails: How to show autovacuum_vacuum_scale_factor per table (p. 171)

@andatki

On page 171, it shows how to change the autovacuum scale factor for a particular table, eg:

ALTER TABLE trips SET (autovacuum_vacuum_scale_factor = 0.01);

It’s also possible to show from in a psql console what the global value is for the scale factor:

SHOW autovacuum_vacuum_scale_factor;

My question is: How to show the table-specific values? i.e. suppose someone else has gone in and updated this for various tables, and you just want to know what all the current values are before making further changes?

First Post!

andatki

andatki

Author of High Performance PostgreSQL for Rails

Hey Daniela! Good question. I’m adding a query (thanks ChatGPT) you can run on your DB to find this information. We can query the pg_class system catalog to get it. To test this, I set the AV scale factor using the command you listed and made sure the expected option name and value appeared in the result.

Because this seems generally useful, I’ve added this query to my pg_scrips repository on GitHub. There’s also a commented out section showing the result when run on my local Rideshare DB.

https://github.com/andyatkinson/pg_scripts/blob/main/per_table_options_reloptions_all_regular_tables.sql

Besides querying this information, another tactic could be adding these changes to your local dev DB, since they’re dumped into the db/structure.sql.

Here’s a snippet below where Autovacuum was disabled for a table, showing the line it adds to db/structure.sql.

While this AV change wouldn’t likely wouldn’t be necessary locally, documenting a change like this in the db/structure.sql could be helpful on a team of people interested in this info.

“+WITH (autovacuum_enabled='false');”

Hope that helps!

Where Next?

Popular Pragmatic Bookshelf topics Top

jon
Some minor things in the paper edition that says “3 2020” on the title page verso, not mentioned in the book’s errata online: p. 186 But...
New
johnp
Hi Brian, Looks like the api for tinydb has changed a little. Noticed while working on chapter 7 that the .purge() call to the db throws...
New
jeffmcompsci
Title: Design and Build Great Web APIs - typo “https://company-atk.herokuapp.com/2258ie4t68jv” (page 19, third bullet in URL list) Typo:...
New
jamis
The following is cross-posted from the original Ray Tracer Challenge forum, from a post by garfieldnate. I’m cross-posting it so that the...
New
alanq
This isn’t directly about the book contents so maybe not the right forum…but in some of the code apps (e.g. turbo/06) it sends a TURBO_ST...
New
New
Chrichton
Dear Sophie. I tried to do the “Authorization” exercise and have two questions: When trying to plug in an email-service, I found the ...
New
brunogirin
When running tox for the first time, I got the following error: ERROR: InterpreterNotFound: python3.10 I realised that I was running ...
New
EdBorn
Title: Agile Web Development with Rails 7: (page 70) I am running windows 11 pro with rails 7.0.3 and ruby 3.1.2p20 (2022-04-12 revision...
New
SlowburnAZ
Getting an error when installing the dependencies at the start of this chapter: could not compile dependency :exla, "mix compile" failed...
New

Other popular topics Top

Devtalk
Reading something? Working on something? Planning something? Changing jobs even!? If you’re up for sharing, please let us know what you’...
1037 19435 386
New
ohm
Which, if any, games do you play? On what platform? I just bought (and completed) Minecraft Dungeons for my Nintendo Switch. Other than ...
New
siddhant3030
I’m thinking of buying a monitor that I can rotate to use as a vertical monitor? Also, I want to know if someone is using it for program...
New
AstonJ
There’s a whole world of custom keycaps out there that I didn’t know existed! Check out all of our Keycaps threads here: https://forum....
New
AstonJ
I have seen the keycaps I want - they are due for a group-buy this week but won’t be delivered until October next year!!! :rofl: The Ser...
New
PragmaticBookshelf
Use WebRTC to build web applications that stream media and data in real time directly from one user to another, all in the browser. ...
New
AstonJ
Biggest jackpot ever apparently! :upside_down_face: I don’t (usually) gamble/play the lottery, but working on a program to predict the...
New
PragmaticBookshelf
Rails 7 completely redefines what it means to produce fantastic user experiences and provides a way to achieve all the benefits of single...
New
RobertRichards
Hair Salon Games for Girls Fun Girls Hair Saloon game is mainly developed for kids. This game allows users to select virtual avatars to ...
New
PragmaticBookshelf
Fight complexity and reclaim the original spirit of agility by learning to simplify how you develop software. The result: a more humane a...
New

Sub Categories: