How to get 4th image of a Product so that I can assign it a particular Attribute (hovering)?

Question

I have a requirement to assign the 4th image of a product a custom attribute 'hover_image', which will be shown when a user hovers over the product on PLP. I have done this using position value stored in DB in table catalog_product_entity_media_gallery_value but it seems that it's not necessarily giving the 4th image of a product and that's why the attribute is assigned to 5th image of some products.

here is my code of the sql query to select products

               $select = $connection->select()
                ->from(
                    ['ent' => $connection->getTableName('catalog_product_entity'),]
                )->joinLeft(
                    ['web' => $connection->getTableName('catalog_product_website')],
                    'ent.entity_id = web.product_id',
                    []
                )->joinLeft(
                    ['gVal' => $connection->getTableName('catalog_product_entity_media_gallery_value')],
                    'gVal.row_id = ent.row_id AND gVal.store_id = 0',
                    ['if (sVal.store_id, sVal.store_id, gVal.store_id) as store_id']
                )->joinLeft(
                    ['sVal' => $connection->getTableName('catalog_product_entity_media_gallery_value')],
                    'sVal.row_id = ent.row_id AND sVal.store_id = ' . $storeId,
                    []
                )->joinRight(
                    ['gal' => $connection->getTableName('catalog_product_entity_media_gallery')],
                    'gal.value_id = if (sVal.value_id, sVal.value_id, gVal.value_id)',
                    ['value']
                )->where(
                    'if (sVal.position, sVal.position, gVal.position) = ?',
                    self::HOVER_IMAGE_POSITION
                    // hover_image is assigned only if product has position 4 image, otherwise attribute empty
                )->where('web.website_id = ?', $websiteId)->group('ent.entity_id');

here is the code for saving products

$connection = $this->resourceConnection->getConnection();
        $connection->beginTransaction();
        try {
            $connection->insertOnDuplicate(
                $connection->getTableName('catalog_product_entity_varchar'),
                $batch
            );
            $connection->commit();
        } catch (Exception $e) {
            $connection->rollBack();
            throw $e;
        }