Allow empty store_ids

Most VSS users don't actually care about the `store_id` - they have
some data which they want to store for themselves (keyed on the
authenticated user id) and that's it. There's not really any reason
to force them to specify a `store_id`, the empty string is just as
valid as any other. Thus we allow it here.

Author: TheBlueMatt

rust/impls/src/migrations.rs

@@ -26,14 +26,15 @@ pub(crate) const MIGRATIONS: &[&str] = &[
 	// We do not complain if the table already exists, as users of VSS could have already created this table
 	"CREATE TABLE IF NOT EXISTS vss_db (
 	    user_token character varying(120) NOT NULL CHECK (user_token <> ''),
-	    store_id character varying(120) NOT NULL CHECK (store_id <> ''),
+	    store_id character varying(120) NOT NULL,
 	    key character varying(600) NOT NULL,
 	    value bytea NULL,
 	    version bigint NOT NULL,
 	    created_at TIMESTAMP WITH TIME ZONE,
 	    last_updated_at TIMESTAMP WITH TIME ZONE,
 	    PRIMARY KEY (user_token, store_id, key)
 	);",
+	"ALTER TABLE vss_db DROP CONSTRAINT IF EXISTS vss_db_store_id_check;",
 ];
 #[cfg(test)]
 pub(crate) const DUMMY_MIGRATION: &str = "SELECT 1 WHERE FALSE;";

rust/impls/src/postgres/sql/v0_create_vss_db.sql

@@ -1,6 +1,6 @@
 CREATE TABLE vss_db (
     user_token character varying(120) NOT NULL CHECK (user_token <> ''),
-    store_id character varying(120) NOT NULL CHECK (store_id <> ''),
+    store_id character varying(120) NOT NULL,
     key character varying(600) NOT NULL,
     value bytea NULL,
     version bigint NOT NULL,