Statically count topic views.

README.md

@@ -11,3 +11,6 @@
  - [node.js](https://nodejs.org/) (for the typescript and less compilers)
  - [Yarn](https://yarnpkg.com/)
 
+## Additional Configuration
+
+Make sure to set the GLOBAL MySQL variable `log_bin_trust_function_creators` to `ON` so the migration script can create stored procedures. I can't automate this because said variable is not changeable at a session scope and only root can touch global variables.

database/2019_03_03_140632_add_static_topic_viewcount.php

@@ -0,0 +1,43 @@
+<?php
+namespace Misuzu\DatabaseMigrations\AddStaticTopicViewcount;
+
+use PDO;
+
+function migrate_up(PDO $conn): void
+{
+    $conn->exec("
+        ALTER TABLE `msz_forum_topics`
+            ADD COLUMN `topic_count_views` INT UNSIGNED NOT NULL DEFAULT '0' AFTER `topic_title`;
+    ");
+
+    $conn->exec("
+        CREATE TRIGGER `msz_forum_topics_track_increase_views`
+        AFTER INSERT ON `msz_forum_topics_track`
+        FOR EACH ROW BEGIN
+            UPDATE `msz_forum_topics`
+            SET `topic_count_views` = `topic_count_views` + 1
+            WHERE `topic_id` = NEW.topic_id;
+        END;
+    ");
+
+    // Restore view counts
+    $conn->exec("
+        UPDATE `msz_forum_topics` AS t
+        INNER JOIN (
+            SELECT `topic_id`, COUNT(`user_id`) AS `count_views`
+            FROM `msz_forum_topics_track`
+            GROUP BY `topic_id`
+        ) AS tt
+        ON tt.`topic_id` = t.`topic_id`
+        SET t.`topic_count_views` = tt.`count_views`
+    ");
+}
+
+function migrate_down(PDO $conn): void
+{
+    $conn->exec("DROP TRIGGER `msz_forum_topics_track_increase_views`");
+    $conn->exec("
+        ALTER TABLE `msz_forum_topics`
+            DROP COLUMN `topic_count_views`;
+    ");
+}