Optimize latest memory queries (#35)

server/migrations/0007_memory_events.sql

@@ -0,0 +1,46 @@
+-- Denormalized latest-per-event view of memory_completions.
+-- Powers /api/memories/latest, /api/memory/:eventId, /api/sitemap.
+-- Update memory_events alongside any schema change to memory_completions.
+CREATE TABLE IF NOT EXISTS memory_events (
+    event_id     TEXT PRIMARY KEY,
+    anim_index   INTEGER NOT NULL,
+    completed_at INTEGER NOT NULL,
+    participants TEXT NOT NULL,
+    language     TEXT NOT NULL
+);
+
+CREATE INDEX IF NOT EXISTS idx_memory_events_completed_at
+    ON memory_events(completed_at DESC);
+
+-- AFTER INSERT does not fire when INSERT OR IGNORE hits the UNIQUE conflict,
+-- so duplicate completions correctly do not update memory_events.
+CREATE TRIGGER IF NOT EXISTS memory_events_after_insert
+AFTER INSERT ON memory_completions
+BEGIN
+    INSERT INTO memory_events (event_id, anim_index, completed_at, participants, language)
+    VALUES (NEW.event_id, NEW.anim_index, NEW.completed_at, NEW.participants, NEW.language)
+    ON CONFLICT(event_id) DO UPDATE SET
+        anim_index   = excluded.anim_index,
+        completed_at = excluded.completed_at,
+        participants = excluded.participants,
+        language     = excluded.language
+    WHERE excluded.completed_at > memory_events.completed_at;
+END;
+
+-- Backfill: pick the latest row per event_id deterministically by (completed_at DESC, id DESC).
+-- UPSERT semantics so writes captured by the trigger between CREATE TRIGGER and now are not clobbered.
+INSERT INTO memory_events (event_id, anim_index, completed_at, participants, language)
+SELECT event_id, anim_index, completed_at, participants, language
+FROM memory_completions mc
+WHERE id = (
+    SELECT id FROM memory_completions mc2
+    WHERE mc2.event_id = mc.event_id
+    ORDER BY completed_at DESC, id DESC
+    LIMIT 1
+)
+ON CONFLICT(event_id) DO UPDATE SET
+    anim_index   = excluded.anim_index,
+    completed_at = excluded.completed_at,
+    participants = excluded.participants,
+    language     = excluded.language
+WHERE excluded.completed_at >= memory_events.completed_at;

server/src/account.ts

@@ -13,6 +13,19 @@ account.delete("/", async (c) => {
 			c.env.DB.prepare("DELETE FROM user_saves WHERE user_id = ?").bind(userId),
 			c.env.DB.prepare("DELETE FROM user_config WHERE user_id = ?").bind(userId),
 			c.env.DB.prepare("DELETE FROM memory_completions WHERE user_id = ?").bind(userId),
+			c.env.DB.prepare(
+				"DELETE FROM memory_events WHERE event_id NOT IN (SELECT event_id FROM memory_completions)"
+			),
+			c.env.DB.prepare(
+				"INSERT INTO memory_events (event_id, anim_index, completed_at, participants, language) " +
+				"SELECT event_id, anim_index, completed_at, participants, language FROM memory_completions mc " +
+				"WHERE id = (SELECT id FROM memory_completions mc2 WHERE mc2.event_id = mc.event_id " +
+				"ORDER BY completed_at DESC, id DESC LIMIT 1) " +
+				"ON CONFLICT(event_id) DO UPDATE SET " +
+				"anim_index = excluded.anim_index, completed_at = excluded.completed_at, " +
+				"participants = excluded.participants, language = excluded.language " +
+				"WHERE excluded.completed_at >= memory_events.completed_at"
+			),
 			c.env.DB.prepare("UPDATE crash_reports SET user_id = NULL WHERE user_id = ?").bind(userId),
 			c.env.DB.prepare('DELETE FROM "session" WHERE "userId" = ?').bind(userId),
 			c.env.DB.prepare('DELETE FROM "account" WHERE "userId" = ?').bind(userId),

server/src/index.ts

@@ -29,7 +29,7 @@ app.all("/api/auth/*", async (c) => {
 // Public endpoint: all memory event IDs for sitemap generation
 app.get("/api/sitemap", async (c) => {
 	const results = await c.env.DB.prepare(
-		"SELECT event_id, MAX(completed_at) AS completed_at FROM memory_completions GROUP BY event_id ORDER BY completed_at DESC"
+		"SELECT event_id, completed_at FROM memory_events ORDER BY completed_at DESC"
 	).all<{ event_id: string; completed_at: number }>();
 
 	return c.json({ entries: results.results });
@@ -43,7 +43,7 @@ app.get("/api/memory/:eventId", async (c) => {
 	}
 
 	const result = await c.env.DB.prepare(
-		"SELECT anim_index, event_id, completed_at, participants, language FROM memory_completions WHERE event_id = ? LIMIT 1"
+		"SELECT anim_index, event_id, completed_at, participants, language FROM memory_events WHERE event_id = ? LIMIT 1"
 	)
 		.bind(eventId)
 		.first<{
@@ -77,17 +77,7 @@ app.get("/api/memory/:eventId", async (c) => {
 // Public endpoint: latest 10 unique memories for the global feed
 app.get("/api/memories/latest", async (c) => {
 	const results = await c.env.DB.prepare(
-		`SELECT mc.anim_index, mc.event_id, mc.completed_at, mc.participants, mc.language
+		"SELECT anim_index, event_id, completed_at, participants, language FROM memory_events ORDER BY completed_at DESC, event_id DESC LIMIT 10"
-		 FROM memory_completions mc
-		 INNER JOIN (
-		     SELECT event_id, MAX(completed_at) AS max_completed_at
-		     FROM memory_completions
-		     GROUP BY event_id
-		     ORDER BY max_completed_at DESC
-		     LIMIT 10
-		 ) latest ON mc.event_id = latest.event_id AND mc.completed_at = latest.max_completed_at
-		 GROUP BY mc.event_id
-		 ORDER BY mc.completed_at DESC`
 	).all<{ anim_index: number; event_id: string; completed_at: number; participants: string; language: string }>();
 
 	const entries = results.results.map((r) => {