MySQL alter efficiency

September 15, 2017 10:36:54 Friday

Today comes an efficiency issue to note:

Scenario: MySQL To change the comment for the table field because of an SQL statement problem that causes the entire table to be updated ...

Error:

ALTER TABLE COLUMN SMALLINT (4notNULLDEFAULT'0'AAAA)  ' after ' Pay_style ';

That's right:

ALTER TABLE COLUMN SMALLINT (4notNULLDEFAULT'0'AAAA)  ';

Get rid of the after ' Pay_style ' on the rear.

In addition, the length of the field, the data structure does not change, otherwise it will scan the entire table for processing

MySQL alter efficiency