Epic: Extension Upgrades

[skyzh]

Motivation

The deployment cannot be rolled back if we upgrade the neon pg extension or any other 3rd party extensions. We need a solution for that. Keeping it for the record there and update the details of this epic later.

https://neondb.slack.com/archives/C04DGM6SMTM/p1709042818937799

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[skyzh]

also some problems with read/write replica with different compute node versions

[skyzh]

#7066

[skyzh]

A viable solution is to put 3rd-party extensions in a bucket, and for neon extensions, always provide a downgrade script.

remote_extension_bucket
  compute-version-4000
    pg-someext1
    pg-someext2
  compute-version-4001
    pg-someext1
    pg-someext2

the extension build process should be decoupled from compute node builds. therefore, when we add a new extension, we should built them against all available versions of compute node.

remote_extension_bucket
  compute-version-4000
    pg-someext1
    pg-someext2
    pg-someext3 <- added extension, also build it for previous versions
  compute-version-4001 <- current latest version
    pg-someext1
    pg-someext2
    pg-someext3 <- added extension

[lubennikovaav]

@skyzh. fyi we already have part of this mechanism
https://github.com/neondatabase/build-custom-extensions

there is no support for different versions of the same extension, yet.
and the spec is now not added into compute, it must be set manually in user settings

[lubennikovaav]

Situation with 3rd party extensions is less dramatic than with neon, because most likely users don't perform
ALTER EXTENSION UPDATE too often. And when they do, it will be "user-space" error, not stuck compute.

Of course this is still a potential issue and we need to fix it properly.