change the primary key to be more valid

chunk ids should only be unique to users, not necessarily across the
whole server

migrations/20240818052859_better_primary_key.sql

@@ -0,0 +1,5 @@
+ALTER TABLE chunks RENAME CONSTRAINT chunks_pkey TO chunks_pkeyold;
+CREATE UNIQUE INDEX chunks_pkey ON chunks (id, user_id);
+ALTER TABLE chunks DROP CONSTRAINT chunks_pkeyold;
+ALTER TABLE chunks ADD PRIMARY KEY USING INDEX chunks_pkey;
+ALTER TABLE chunks ADD CONSTRAINT unique_id_user_id UNIQUE (id, user_id);

src/meta_db.rs

@@ -153,7 +153,7 @@ impl MetaDB for PostgresMetaDB {
         user_id: i64,
     ) -> Result<Option<ChunkMetadata>> {
         Ok(sqlx::query(
-            "select chunk_size, nonce, indice from chunks where id = $1 and user_id = $2",
+            "select chunk_size, nonce, hash, indice from chunks where id = $1 and user_id = $2",
         )
         .bind(chunk_id.to_string())
         .bind(user_id)