I am running the migration script for a Magento 1.9.3.7 to a Magento 2.3 install.

The store has less than 700 products and maybe 20K customers.

The script is stuck on log step and when I run Mytop, this is the SQL that I see for the past 3 days:

SELECT lv.visitor_id, lc.customer_id, lv.session_id, lv.last_visit_at FROM log_visitor AS lv LEFT JOIN log_customer AS lc ON lv.visitor_id = lc.visitor_id GROUP BY lv.visitor_id ORDER BY lv.visitor_id ASC LIMIT 10000 OFFSET 5440000

My question is, if I wanted to create an index on visitor_id in both tables before this step and drop the index after this step, what do I need to do? What do I have to change and where? Obviously having an index on vistor_id in both tables will help this query run a lot faster

any help is appreciated.

Thank you