perf: improve metrics query performance (#1052)

The current query is not using any indices due to the CASE statement.
Using `UNION`, we're now able to take advantage of tables indices, and
have a more faster query

Author: wa0x6e

src/helpers/metrics.ts

@@ -96,23 +96,19 @@ new client.Gauge({
   labelNames: ['status'],
   async collect() {
     const statusResults = await db.queryAsync(`
-      SELECT 
-        SUM(CASE WHEN verified > 0 THEN 1 ELSE 0 END) AS verified,
-        SUM(CASE WHEN flagged > 0 THEN 1 ELSE 0 END) AS flagged,
-        SUM(CASE WHEN hibernated > 0 THEN 1 ELSE 0 END) AS hibernated,
-        SUM(CASE WHEN turbo_expiration > UNIX_TIMESTAMP() THEN 1 ELSE 0 END) AS active_turbo,
-        SUM(CASE WHEN turbo_expiration > 0 AND turbo_expiration <= UNIX_TIMESTAMP() THEN 1 ELSE 0 END) AS expired_turbo
-      FROM spaces
+      SELECT 'verified' as status, COUNT(*) as count FROM spaces WHERE verified > 0
+      UNION ALL
+      SELECT 'flagged' as status, COUNT(*) as count FROM spaces WHERE flagged > 0
+      UNION ALL
+      SELECT 'hibernated' as status, COUNT(*) as count FROM spaces WHERE hibernated > 0
+      UNION ALL
+      SELECT 'active_turbo' as status, COUNT(*) as count FROM spaces WHERE turbo_expiration > UNIX_TIMESTAMP()
+      UNION ALL
+      SELECT 'expired_turbo' as status, COUNT(*) as count FROM spaces WHERE turbo_expiration > 0 AND turbo_expiration <= UNIX_TIMESTAMP()
     `);
 
-    [
-      'verified',
-      'flagged',
-      'hibernated',
-      'active_turbo',
-      'expired_turbo'
-    ].forEach(status => {
-      this.set({ status }, statusResults[0][status]);
+    statusResults.forEach((row: any) => {
+      this.set({ status: row.status }, row.count);
     });
   }
 });

src/helpers/mysql.ts

@@ -34,7 +34,9 @@ sequencerConfig.connectTimeout = 60e3;
 sequencerConfig.acquireTimeout = 60e3;
 sequencerConfig.timeout = 60e3;
 sequencerConfig.charset = 'utf8mb4';
-sequencerConfig.ssl = { rejectUnauthorized: sequencerConfig.host !== 'localhost' };
+sequencerConfig.ssl = {
+  rejectUnauthorized: sequencerConfig.host !== 'localhost'
+};
 
 const sequencerDB = mysql.createPool(sequencerConfig);