Hi, I have two questions: 1. In our PostgreSQL database, all of the

relation_tuple

rows were logically deleted (their

deleted_xid

was set). We're not sure what caused it, but we found that the following query was executed six times: UPDATE relation_tuple SET deleted_xid = $1 WHERE deleted_xid = $2 AND namespace = $3; Are you familiar with this query? Could you explain exactly what it is supposed to do and under what circumstances SpiceDB executes it? 2. I noticed entries in the

alembic_version

table such as

create-relationship-counters-table

and

add-index-for-transaction-gc

. What exactly do these values represent? Are they migration identifiers, and what changes do they indicate were applied to the database?

1. the

DeleteRelationships

api will use that query if you don't give it any additional filters. 1. yes, migration identifiers. it's a string identifier for a migration that's defined in the SpiceDB code. you're welcome to [inspect them](https://github.com/authzed/spicedb/tree/main/internal/datastore/postgres/migrations).

Thank you. Can the Delete API be triggered during a migration downgrade? Also, does one of the flags indicate that a migration has been performed? If so, is there a way to determine when the migration occurred?

no - migrations intentionally do not ever touch data. there also isn't a reverse path for migrations - they're mostly used for stepping four-phase migrations and ensuring that all of the migrations necessary for a given version have been run.

So, if my database has never gone through any migrations, should the alembic_version table be empty?

correct, if it even exists at all

Ok thanks alot🙏🏽

sure thing!