Remove unused last_used column from access_tokens table

[clokep]

The last_used column on access_tokens is unused, we should remove it.

See #8970 (comment)_

[clokep]

This is a bit more of a faff than expected since sqlite cannot drop columns directly, e.g. check out synapse/storage/databases/main/schema/delta/46/user_dir_null_room_ids.sql

[jerinjtitus]

So, it should be dropped from the sql files, right? And is it just required to be removed for sqlite or also for postgres.

[clokep]

So, it should be dropped from the sql files, right?

A new migration file needs to be added that drops the column.

And is it just required to be removed for sqlite or also for postgres.

It should be done for both.

[jerinjtitus]

A new migration file needs to be added that drops the column.

I was going through those files; I guess I have to create like a buffer table in the new migration file and copy the values from the previous one and then drop it. Then rename the new table. Am I right so far?

[clokep]

That's pretty much what is done in synapse/storage/databases/main/schema/delta/46/user_dir_null_room_ids.sql, so I think it is right.

[jerinjtitus]

Can you help me with understanding how exactly this classification works? And are all the migrations automatically made if directly added to the appropriate directory?

[richvdh]

Just add a new migration to the most recent delta directory, with a new number.

There is a bit of documentation about the system at https://github.com/matrix-org/synapse/blob/develop/synapse/storage/prepare_database.py#L288, but it needs an update to be honest.

[jerinjtitus]

Just add a new migration to the most recent delta directory, with a new number.

There is a bit of documentation about the system at https://github.com/matrix-org/synapse/blob/develop/synapse/storage/prepare_database.py#L288, but it needs an update to be honest.

Thanks

[clokep]

Fixed in #9025.