Pacemaker in action at 

At the beginning of the project, it was clear that a large number of products had to be imported and the Magento 2 standard import couldn't possibly be the best solution. Besides the considerable amount of products, one requirement was to be able to provide one complete file with all the necessary data to import. Since it was an immense effort for Gabor to provide one file to import the decision was made to use four bunches. Each of the four bunches containing parts of the data, have to be imported and then linked again.

Based on the bunch functionality, which was initially not tailored to these requirements, it was possible to import the four bunches one after another without any additional implementation effort, starting with all simple products, followed by their link types, images, and status information, whereby the data could not be merged beforehand. To ensure data consistency, the entire process was packaged into one transaction that ensures that either the complete data is updated or the import is reset in the event of an error.

When the GABOR marketplace went online, around 4,000 products had to be imported with a website, a store and a store view. Since Gabor could not provide a delta update, ~250,000 products including link types, images and prices had to be updated daily. The most massive CSV file contains ~620,000 lines (~123 MB), while the smallest one contains ~14,000 lines (~5 MB). 
Single Transaction mode ensures that product, price and inventory updates, whether full or delta, are always consistent and either complete or not performed at all. Single Transaction mode can significantly speed up the import process, since all DML statements are processed at once to obtain the data in the database as soon as the transaction is transferred. For more details, see the Customer Success Story on the TechDivision implementation partner's website.