add partial index on odid, and search odid as well

the odid != 0 check in cards_for_deck.sql is necessary for sqlite
to be able to take advantage of the index

rslib/src/decks/mod.rs

@@ -366,8 +366,6 @@ impl Collection {
     }
 
     fn delete_all_cards_in_normal_deck(&mut self, did: DeckID) -> Result<()> {
-        // fixme: need to search on odid as well
-        // fixme: the odid requirement will require a table scan, which will be slow when deleting a large tree
         let cids = self.storage.all_cards_in_single_deck(did)?;
         self.remove_cards_inner(&cids)
     }

rslib/src/storage/deck/cards_for_deck.sql

@@ -0,0 +1,9 @@
+select
+  id
+from cards
+where
+  did = ?1
+  or (
+    odid != 0
+    and odid = ?1
+  )

rslib/src/storage/deck/mod.rs

@@ -117,7 +117,7 @@ impl SqliteStorage {
 
     pub(crate) fn all_cards_in_single_deck(&self, did: DeckID) -> Result<Vec<CardID>> {
         self.db
-            .prepare_cached("select id from cards where did = ?")?
+            .prepare_cached(include_str!("cards_for_deck.sql"))?
             .query_and_then(&[did], |r| r.get(0).map_err(Into::into))?
             .collect()
     }

rslib/src/storage/upgrades/schema11_downgrade.sql

@@ -5,6 +5,7 @@ drop table fields;
 drop table templates;
 drop table notetypes;
 drop table decks;
+drop index idx_cards_odid;
 update col
 set
   ver = 11;

rslib/src/storage/upgrades/schema15_upgrade.sql

@@ -35,6 +35,9 @@ create table decks (
   kind bytes not null
 );
 create unique index idx_decks_id on decks (id);
+create index idx_cards_odid on cards (odid)
+where
+  odid != 0;
 update col
 set
   ver = 15;