Add database index to fix slow post editing on large sites

src/config/migrations/20260213152939_AddPrimaryFocusKeywordIndex.php

@@ -0,0 +1,60 @@
+<?php
+
+namespace Yoast\WP\SEO\Config\Migrations;
+
+use Yoast\WP\Lib\Migrations\Migration;
+use Yoast\WP\Lib\Model;
+
+/**
+ * AddPrimaryFocusKeywordIndex class.
+ *
+ * Adds a composite index to improve performance of duplicate focus keyword lookups.
+ * This index speeds up queries that check for existing usage of focus keywords,
+ * reducing query time from ~1.5s to ~0.001s on large sites (800K+ rows).
+ *
+ * @see https://github.com/Yoast/wordpress-seo/issues/22933
+ */
+class AddPrimaryFocusKeywordIndex extends Migration {
+
+	/**
+	 * The plugin this migration belongs to.
+	 *
+	 * @var string
+	 */
+	public static $plugin = 'free';
+
+	/**
+	 * Migration up.
+	 *
+	 * @return void
+	 */
+	public function up() {
+		$this->add_index(
+			$this->get_table_name(),
+			[ 'primary_focus_keyword', 'object_type', 'post_status', 'object_id' ],
+			[ 'name' => 'primary_focus_keyword_and_object_type' ]
+		);
+	}
+
+	/**
+	 * Migration down.
+	 *
+	 * @return void
+	 */
+	public function down() {
+		$this->remove_index(
+			$this->get_table_name(),
+			[ 'primary_focus_keyword', 'object_type', 'post_status', 'object_id' ],
+			[ 'name' => 'primary_focus_keyword_and_object_type' ]
+		);
+	}
+
+	/**
+	 * Retrieves the table name to use for storing indexables.
+	 *
+	 * @return string The table name to use.
+	 */
+	protected function get_table_name() {
+		return Model::get_table_name( 'Indexable' );
+	}
+}