From 3ffb37270d0826729274fddb05284ccc531e102e Mon Sep 17 00:00:00 2001
From: Damien Elmes <gpg@ankiweb.net>
Date: Sat, 2 May 2020 13:30:13 +1000
Subject: [PATCH] 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                            | 2 --
 rslib/src/storage/deck/cards_for_deck.sql         | 9 +++++++++
 rslib/src/storage/deck/mod.rs                     | 2 +-
 rslib/src/storage/upgrades/schema11_downgrade.sql | 1 +
 rslib/src/storage/upgrades/schema15_upgrade.sql   | 3 +++
 5 files changed, 14 insertions(+), 3 deletions(-)
 create mode 100644 rslib/src/storage/deck/cards_for_deck.sql

diff --git a/rslib/src/decks/mod.rs b/rslib/src/decks/mod.rs
index 03d447c5c..ae907d3dd 100644
--- a/rslib/src/decks/mod.rs
+++ b/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)
     }
diff --git a/rslib/src/storage/deck/cards_for_deck.sql b/rslib/src/storage/deck/cards_for_deck.sql
new file mode 100644
index 000000000..6c9cfb1f3
--- /dev/null
+++ b/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
+  )
\ No newline at end of file
diff --git a/rslib/src/storage/deck/mod.rs b/rslib/src/storage/deck/mod.rs
index 11c49ce7e..89cbbc011 100644
--- a/rslib/src/storage/deck/mod.rs
+++ b/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()
     }
diff --git a/rslib/src/storage/upgrades/schema11_downgrade.sql b/rslib/src/storage/upgrades/schema11_downgrade.sql
index 14bacf26c..ec1bd7713 100644
--- a/rslib/src/storage/upgrades/schema11_downgrade.sql
+++ b/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;
\ No newline at end of file
diff --git a/rslib/src/storage/upgrades/schema15_upgrade.sql b/rslib/src/storage/upgrades/schema15_upgrade.sql
index c8bb2ce0d..084dd9be1 100644
--- a/rslib/src/storage/upgrades/schema15_upgrade.sql
+++ b/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;