mysql - Altering the data type of a column in a HUGE table. Performance issues -

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i want run on table:

alter table table_name modify col_name varchar(255)

but table huge, has more 65m (65 million) rows. when execute, takes 50mins execute command. better way alter table?

well, need 

 alter table table_name change col_name new_name varchar(255)

but, right, takes while make change. there isn't faster way change table in mysql.

is concern downtime during change? if so, here's possible approach: copy table new one, change column name on copy, rename copy.

you have figured out routinely changing column names in tables in production system not idea.


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