Feasibility of migrating from pgvecto.rs to VectorChord just through the provided Docker images

[mertalev]

Hi! I'm working on migrating Immich from pgvecto.rs to VectorChord and so far it seems like it has to be a multi-phase operation:

1. Set an env to instruct the server to remove any reference to pgvecto.rs
2. Start the server and DB
3. Bring down server and DB (only after the server is finished changing types, dropping indices and the extension itself)
4. Change image name to the new vectorchord image
5. Bring the server and DB back up

Without these steps, any operation on these columns leads to ERROR: could not access file "$libdir/vectors": No such file or directory. I'm wondering if there's a way to make this simpler for admins with less room for error. One solution would be to install both extensions in the same image, which removes steps 1, 2 and 3 (and without a timing concern). We're considering this but would like to avoid rolling our own images if possible.

Would shipping pgvecto.rs with these images be an option? Or depending on how much of the pgvecto.rs functionality is needed, it could maybe contain a "dummy" library that's just enough to perform the migration?

[VoVAllen]

We've worked with one user moving to VectorChord. I think the easiest way is to bring those two extensions together. For minimal risk, you can copy existing column to a new one with pgvector type. And build index on that, and alter/swap the column name. This minimizes the potential risks.

[mertalev]

I think the easiest way is to bring those two extensions together.

This is where I landed as well and what the migration guide recommends, but this isn't possible when going from the pgvecto.rs image to the official VectorChord image. Using the official images would ideally be one of the easiest ways since they prepare environments for you, rather than the hardest.

[VoVAllen]

I think we can prepare a dedicated image for migration, which contains pgvecto.rs and vectorchord together. And user can use vectorchord-only image after migration, or keep use the migration image won't have any problems. What do you think?

[mertalev]

That would be perfect!

[xieydd]

@mertalev Sure, could you please specify the versions of pgvecto.rs and vectorchord you require?

[mertalev]

pgvecto.rs 0.3.0 is backward compatible with 0.2.0, right? 0.3.0 should cover the range of versions we support (0.2.0 - 0.3.0). The latest release of VectorChord would be best.