fix: performance issues

apps/web/src/routes/dashboard.ts

@@ -186,33 +186,29 @@ export const dashboard = new Elysia()
     if (!accountId) return redirect("/dashboard");
 
     const monitors = await sql`
-      SELECT m.*, (
-        SELECT row_to_json(p) FROM pings p
-        WHERE p.monitor_id = m.id ORDER BY p.checked_at DESC LIMIT 1
-      ) as last_ping
-      FROM monitors m WHERE m.account_id = ${accountId}
-      ORDER BY m.created_at DESC
+      SELECT * FROM monitors WHERE account_id = ${accountId} ORDER BY created_at DESC
     `;
 
-    const monitorIds = monitors.map((m: any) => m.id);
-    let pingsMap: Record<string, any[]> = {};
-    if (monitorIds.length > 0) {
-      const allPings = await sql`
-        SELECT * FROM (
-          SELECT p.*, ROW_NUMBER() OVER (PARTITION BY p.monitor_id, COALESCE(p.region,'__none__') ORDER BY p.checked_at DESC) as rn
-          FROM pings p WHERE p.monitor_id = ANY(${monitorIds})
-        ) sub WHERE rn <= 20 ORDER BY monitor_id, checked_at ASC
-      `;
-      for (const p of allPings) {
-        if (!pingsMap[p.monitor_id]) pingsMap[p.monitor_id] = [];
-        pingsMap[p.monitor_id].push(p);
-      }
-    }
+    // One simple indexed query per monitor, run in parallel. Each is an index
+    // seek on (monitor_id, checked_at DESC) — microseconds. Trivially scalable
+    // and easy to reason about.
+    const pingResults = await Promise.all(
+      monitors.map((m: any) => sql`
+        SELECT * FROM pings
+        WHERE monitor_id = ${m.id}
+        ORDER BY checked_at DESC
+        LIMIT 20
+      `)
+    );
 
-    const monitorsWithPings = monitors.map((m: any) => ({
+    const monitorsWithPings = monitors.map((m: any, i: number) => {
+      const recent = pingResults[i] as any[]; // DESC order
+      return {
         ...m,
-      pings: pingsMap[m.id] || [],
-    }));
+        last_ping: recent[0] ?? null,
+        pings: recent.slice().reverse(), // sparkline expects chronological ASC
+      };
+    });
 
     return html("home", { nav: "monitors", monitors: monitorsWithPings, accountId });
   })