"tuple concurrently updated" with Postgres

Describe the bug

Error while creating a view in postgres

  deadlock detected
  DETAIL:  Process 187 waits for ShareLock on transaction 19479; blocked by process 186.
  Process 186 waits for ShareLock on transaction 19480; blocked by process 187.
  HINT:  See server log for query details.
  CONTEXT:  while updating tuple (1,11) in relation "pg_class"

Occassionally also throws this: tuple concurrently updated

Steps To Reproduce

Have 2 sql files under the same model - they work when only one exists. But when two exist in the same folder (model), the error above throws.

The two sql files refer to different tables within the same schema.

Expected behavior

2 views should be created without errors

System information

Which database are you using dbt with?

• postgres
• redshift
• bigquery
• snowflake
• other (specify: ____________)

The output of dbt --version:

installed version: 0.19.1
   latest version: 0.19.2

Your version of dbt is out of date! You can find instructions for upgrading here:
https://docs.getdbt.com/docs/installation

Plugins:
  - redshift: 0.19.1
  - bigquery: 0.19.1
  - snowflake: 0.19.1
  - postgres: 0.19.1

The operating system you’re using: Ubuntu 20.0.4

The output of python --version: Python 3.8.5

[jtcohen6]

@sdabhi23 My sense is, those two grant statements need to be running concurrently to hit this error. I imagine the view models and grant statements each take <1s to execute. The error will raise only when the queries overlap, which may not be in every invocation.

[sdabhi23]

@jtcohen6 I agree that issue is with concurrent grants. But do you have any idea why this behaviour is flaky?

I mean sometimes it fails sometimes it doesn’t. That’s the behaviour I have observed. It only failed when those 2 particular views were running concurrently.

I will definitely switch to model specific grants, but just a thought