From f3c9e78d6699cc4c8e237a39f0c709519c42eefd Mon Sep 17 00:00:00 2001
From: Mark Liffiton <liffiton@gmail.com>
Date: Tue, 16 Jul 2024 11:53:05 -0500
Subject: [PATCH] Optimize queries: add indexes and help older query planners.

---
 .../20240716--codehelp--add-indexes.sql         | 17 +++++++++++++++++
 src/codehelp/schema.sql                         |  8 ++++++++
 src/gened/instructor.py                         |  2 +-
 3 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 src/codehelp/migrations/20240716--codehelp--add-indexes.sql

diff --git a/src/codehelp/migrations/20240716--codehelp--add-indexes.sql b/src/codehelp/migrations/20240716--codehelp--add-indexes.sql
new file mode 100644
index 0000000..8776b80
--- /dev/null
+++ b/src/codehelp/migrations/20240716--codehelp--add-indexes.sql
@@ -0,0 +1,17 @@
+-- SPDX-FileCopyrightText: 2024 Mark Liffiton <liffiton@gmail.com>
+--
+-- SPDX-License-Identifier: AGPL-3.0-only
+
+BEGIN;
+
+DROP INDEX IF EXISTS queries_by_user;
+CREATE INDEX queries_by_user ON queries(user_id);
+DROP INDEX IF EXISTS queries_by_role;
+CREATE INDEX queries_by_role ON queries(role_id);
+
+DROP INDEX IF EXISTS tutor_chats_by_user;
+CREATE INDEX tutor_chats_by_user ON tutor_chats(user_id);
+DROP INDEX IF EXISTS tutor_chats_by_role;
+CREATE INDEX tutor_chats_by_role ON tutor_chats(role_id);
+
+COMMIT;
diff --git a/src/codehelp/schema.sql b/src/codehelp/schema.sql
index eb4597f..b2b638c 100644
--- a/src/codehelp/schema.sql
+++ b/src/codehelp/schema.sql
@@ -22,6 +22,10 @@ CREATE TABLE queries (
     FOREIGN KEY(user_id) REFERENCES users(id),
     FOREIGN KEY(role_id) REFERENCES roles(id)
 );
+DROP INDEX IF EXISTS queries_by_user;
+CREATE INDEX queries_by_user ON queries(user_id);
+DROP INDEX IF EXISTS queries_by_role;
+CREATE INDEX queries_by_role ON queries(role_id);
 
 DROP TABLE IF EXISTS tutor_chats;
 CREATE TABLE tutor_chats (
@@ -34,3 +38,7 @@ CREATE TABLE tutor_chats (
     FOREIGN KEY(user_id) REFERENCES users(id),
     FOREIGN KEY(role_id) REFERENCES roles(id)
 );
+DROP INDEX IF EXISTS tutor_chats_by_user;
+CREATE INDEX tutor_chats_by_user ON tutor_chats(user_id);
+DROP INDEX IF EXISTS tutor_chats_by_role;
+CREATE INDEX tutor_chats_by_role ON tutor_chats(role_id);
diff --git a/src/gened/instructor.py b/src/gened/instructor.py
index 6c3ec35..042a7dd 100644
--- a/src/gened/instructor.py
+++ b/src/gened/instructor.py
@@ -25,7 +25,7 @@
 def get_queries(class_id: int, user: int | None = None) -> list[Row]:
     db = get_db()
 
-    where_clause = "WHERE roles.class_id=?"
+    where_clause = "WHERE UNLIKELY(roles.class_id=?)"  # UNLIKELY() to help query planner in older sqlite versions
     params = [class_id]
 
     if user is not None: