Bug #97981 Table row_format can be changed instantly in some cases

• Submitted: 13 Dec 2019 8:03
• Modified: 3 Feb 2020 14:42
• Reporter: Pavel Katiushyn
• Status: Verified
• Category: MySQL Server: DDL
• Severity: S4 (Feature request)
• Version: 5.7.28
• OS: Any
• CPU Architecture: Any

[13 Dec 2019 8:03] Pavel Katiushyn

Description:
If the value of innodb_default_row_format variable and in alter are the same, the alter may be instant.

How to repeat:
CREATE TABLE t1(
...
) ENGINE=InnoDB ROW_FORMAT=DYNAMIC;

set innodb_default_row_format=dynamic;

alter table t1 row_format=default;
CREATE TABLE t1(
...
) ENGINE=InnoDB;

alter table t1 row_format=DYNAMIC;

CREATE TABLE t1(
...
) ENGINE=InnoDB ROW_FORMAT=DYNAMIC;

[13 Dec 2019 8:15] Pavel Katiushyn

So basically this is the cases when alter changes between row_format=default and row_format=some value, but the table row_format is not changing actually.

[3 Feb 2020 14:42] MySQL Verification Team

Hello Mr. Katiushyn,

Thank you for your feature request.

I tested your example with 20.000 rows table and the change is not instant at all. Actually it takes time. Also, if I ALTER TABLE to the same row format,  over and over again, each time I run it, the operation takes the same time.

I am verifying your feature request. Thank you .....