[MySQL Help] A friend asked: how to quickly repeat data in an Innodb table with million records

My friend asked:

50 million how to deduplicate a table with data and determine whether the table is repeated based on the two fields.

Reply:
Select two fields and the primary key id to create a temporary table t1,
T1 is used to establish a primary key index and a joint index of two comparative fields.
Then compare duplicate records in the temporary table,
Record the duplicate data to the second temporary table t2. The structure of table t2 is exactly the same as that of table t1.
Then, you can decide how to process the repeated records in Table t2 based on your business, and associate table t2 with the original million records for processing,
Generally, the group by2 field is used to retrieve records with a large primary key id and delete them.