Why such huge MySQL table size after import?

Question

MySQL

When transferring MySQL database from server to server, a wild situation occurred.
MySQL 5.6 was running on the old server, the table was indexed - the exported version of the database occupied about 1GB.
On the new server, I put it off. MySQL 5.7 repositories and imported the database
But for some reason +13GB was added to the database - where did it come from?

For the sake of interest, using PHP, I copied the same table to another (SELECT & INSERT), and then indexed it, the size is 1.1 GB

product_types 3 - Table from import
product_types - copied table using php

Who can explain because of what such gain in volume of a DB after import?

Answer 1

OPTIMIZE TABLE product_types3