I just want to share my experience as it might help someone here.
I created this new wordpress/woocemmerce site for a client and setup everything fine.
They moved from a drupal eshop to a new wordpress/woocommerce setup.
They already had some thousands transactions in their drupal eshop and their online credit card processing system (Piraeus bank)
So far so good. Here the problems start.
Their online credit card processing provider (Piraeus bank) handles all transactions sequentially and can not change these. So naturally, my woocommerce orders CAN NOT START from 0001 for example.
So I thought OK, I have to alter the order number
I Did that with Booster for WooCommerce which by the way is SOOO worth it. But the NEW ORDER NUMBER I set in the back end of woocommerce does not reflect on the order_id set in the database. That number is an auto increment number that is used for all post types in wordpress!
My payment gateway (Piraeus bank Gateway) uses the order_id (woocommerce orders post id number in other words) to send and receive order success/failure etc so I needed to change that incremental number of the posts
My solution after trying and researching was to go into phpMyAdmin and go to the table POSTS. There in the tab OPERATIONS I set AUTO_INCREMENT = to something larger than the last transaction number before migrating to the wordpress/woocommerce setup.
Now their online credit card processing provider receives a number greater than the last Drupal installation and everything works fine. I know its not ideal. The best would be to have a plugin match ORDER_ID with ORDER NUMBER.
There you go….