create table t (a int NOT NULL) engine=innodb row_format=   compressed;
alter table t modify a int NULL, algorithm=instant;
ERROR 0A000: ALGORITHM=INSTANT is not supported for this operation. Try ALGORITHM=INPLACE
drop table t;
create table t (a int NOT NULL) engine=innodb row_format=   dynamic;
alter table t modify a int NULL, algorithm=instant;
ERROR 0A000: ALGORITHM=INSTANT is not supported for this operation. Try ALGORITHM=INPLACE
drop table t;
create table t (a int NOT NULL) engine=innodb row_format=   compact;
alter table t modify a int NULL, algorithm=instant;
ERROR 0A000: ALGORITHM=INSTANT is not supported for this operation. Try ALGORITHM=INPLACE
drop table t;
create table t (
id int primary key,
a int NOT NULL default 0,
b int NOT NULL default 0,
c int NOT NULL default 0,
index idx (a,b,c)
) engine=innodb row_format=redundant;
insert into t (id, a) values (0, NULL);
ERROR 23000: Column 'a' cannot be null
insert into t (id, b) values (0, NULL);
ERROR 23000: Column 'b' cannot be null
insert into t (id, c) values (0, NULL);
ERROR 23000: Column 'c' cannot be null
insert into t values (1,1,1,1);
set @id = (select table_id from information_schema.innodb_sys_tables
where name = 'test/t');
select * from information_schema.innodb_sys_columns where table_id=@id;
TABLE_ID	NAME	POS	MTYPE	PRTYPE	LEN
TABLE_ID	id	0	6	1283	4
TABLE_ID	a	1	6	1283	4
TABLE_ID	b	2	6	1283	4
TABLE_ID	c	3	6	1283	4
alter table t modify a int NULL, algorithm=instant;
insert into t values (2, NULL, 2, 2);
alter table t modify b int NULL, algorithm=nocopy;
insert into t values (3, NULL, NULL, 3);
alter table t modify c int NULL, algorithm=inplace;
insert into t values (4, NULL, NULL, NULL);
select * from information_schema.innodb_sys_columns where table_id=@id;
TABLE_ID	NAME	POS	MTYPE	PRTYPE	LEN
TABLE_ID	id	0	6	1283	4
TABLE_ID	a	1	6	1027	4
TABLE_ID	b	2	6	1027	4
TABLE_ID	c	3	6	1027	4
select * from t;
id	a	b	c
4	NULL	NULL	NULL
3	NULL	NULL	3
2	NULL	2	2
1	1	1	1
check table t;
Table	Op	Msg_type	Msg_text
test.t	check	status	OK
drop table t;