What happened?

Description

I am building a batched job that pulls data from an external database and this did not seem to work completely. I believe I have found a bug in the QueryBatcher.php. In the QueryBatcher class you can pass along a Connection variable called $db. In that class the count() function does use the $this->db to pass along to the query. However the getSlice() function does not use the $this->db in the ->all() function. The result is that the Count() is done on connection A but the getSlice() is done on connection B. Which in my opinion is incorrect. For now I created my own QueryBatcher class so I can continue my development.

Steps to reproduce

1. In the app.php add an alternative connection

       'legacydb' => [
    		'class' => yii\db\Connection::class,
    		'dsn' => 'mysql:host=' . App::env('LEGACY_DB_SERVER') . ';dbname=' . App::env('LEGACY_DB_DATABASE') . ';port=' . App::env('LEGACY_DB_PORT'),
    		'username' => App::env('LEGACY_DB_USER'),
    		'password' => App::env('LEGACY_DB_PASSWORD'),
    		'tablePrefix' => App::env('LEGACY_DB_TABLE_PREFIX'),
    		'charset' => 'utf8',
    	],
   

2. Create a job class that extends the BaseBatchedJob
3. In the loadData() function get the alternative connection using $connection = Craft::$app->get('legacydb');
4. Return the QueryBatcher with a connection return new QueryBatcher($query, $connection);
5. Set a breakpoint on line 82 with the code $slice = $query
6. Inspect the value of $slice this should not be the expected data

The fix is to change line 85 from:
->all();
to
->all($this->db);

Expected behavior

The QueryBatcher::getSlice uses the provided connection to perform the query on.

Actual behavior

The QueryBatcher::getSlice uses the default connection to perform the query on.

Craft CMS version

5.6.1

PHP version

8.2.7

Operating system and version

Linux 6.6.65-1-MANJARO

Database type and version

MySQL 8.0.21

Image driver and version

GD 8.2.7

Installed plugins and versions