Question

I have an InnoDB table in MySQL which used to contain about 600k rows. After deleting 400k+ rows, my guess is that I need to run an OPTIMIZE.

However, since the table will be locked during this operation, the site will not be usable at that time. So, my question is: should I run the optimize on the live database table (with a little under 200k rows)? Or is it possible to create a copy of that table, run the OPTIMIZE on that copy and after that rename both tables so the copy the data back to the live table?

Answer 1

If you create a copy, then it should be optimised already if you do CREATE TABLE..AS SELECT... No need to run it separately

However, I’d consider copy the 200k rows to keep into a new table, then renaming the tables.
This way is less steps and less work all round.

CREATE TABLE MyTableCopy AS
SELECT *
FROM myTable
WHERE (insert Keep condition here);

RENAME TABLE
    myTable TO myTable_DeleteMelater, 
    MyTableCopy TO myTable;