Add migration to fix wrong index on type (fixes #1884)

Signed-off-by: Julius Härtl <jus@bitgrid.net>

lib/Migration/Version1000Date20200308073933.php

@@ -39,7 +39,8 @@ class Version1000Date20200308073933 extends SimpleMigrationStep {
 			'notnull' => true,
 			'default' => 0
 		]);
-		$table->addIndex(['participant'], 'deck_assigned_users_idx_t');
+		//$table->addIndex(['participant'], 'deck_assigned_users_idx_t');
+		$table->addIndex(['type'], 'deck_assigned_users_idx_ty');
 
 		return $schema;
 	}

lib/Migration/Version10200Date20201111150114.php

@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OCA\Deck\Migration;
+
+use Closure;
+use OCP\DB\ISchemaWrapper;
+use OCP\Migration\IOutput;
+use OCP\Migration\SimpleMigrationStep;
+
+class Version10200Date20201111150114 extends SimpleMigrationStep {
+
+
+	function preSchemaChange(IOutput $output, Closure $schemaClosure, array $options): void {
+	}
+
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
+		/** @var ISchemaWrapper $schema */
+		$schema = $schemaClosure();
+
+		// Fix wrong index added in Version1000Date20200308073933
+		$table = $schema->getTable('deck_assigned_users');
+		if ($table->hasIndex('deck_assigned_users_idx_t')) {
+			$table->dropIndex('deck_assigned_users_idx_t');
+			if (!$table->hasIndex('deck_assigned_users_idx_ty')) {
+				$table->addIndex(['type'], 'deck_assigned_users_idx_ty');
+			}
+		}
+
+		return $schema;
+	}
+
+	public function postSchemaChange(IOutput $output, Closure $schemaClosure, array $options): void {
+	}
+}