MariaDB [test]> DROP TABLE IF EXISTS test_online;
Query OK, 0 rows affected (0.14 sec)

MariaDB [test]> CREATE TABLE test_online(id INT AUTO_INCREMENT PRIMARY KEY, handle INT, DATA BIGINT NOT NULL DEFAULT 0) engine = innodb;
Query OK, 0 rows affected (0.36 sec)

MariaDB [test]> INSERT INTO test_online(handle) VALUES(12),(54),(546);
Query OK, 3 rows affected (0.04 sec)
Records: 3  Duplicates: 0  Warnings: 0

MariaDB [test]> SELECT *, md5(handle) FROM test_online;
+----+--------+------+----------------------------------+
| id | handle | DATA | md5(handle)                      |
+----+--------+------+----------------------------------+
|  1 |     12 |    0 | c20ad4d76fe97759aa27a0c99bff6710 |
|  2 |     54 |    0 | a684eceee76fc522773286a895bc8436 |
|  3 |    546 |    0 | ed265bc903a5a097f61d3ec064d96d2e |
+----+--------+------+----------------------------------+
3 rows in set (0.08 sec)

MariaDB [test]> ALTER TABLE test_online ADD INDEX handle(handle), algorithm=inplace; 
Query OK, 0 rows affected (0.30 sec)
Records: 0  Duplicates: 0  Warnings: 0

MariaDB [test]> ALTER TABLE test_online ADD COLUMN hash VARCHAR(32) AS (md5(handle)) persistent, ADD UNIQUE INDEX hash(hash), algorithm=inplace;
ERROR 1845 (0A000): ALGORITHM=INPLACE is not supported for this operation. Try ALGORITHM=COPY.
MariaDB [test]> ALTER TABLE test_online ADD COLUMN hash VARCHAR(32) AS (md5(handle)) persistent, algorithm=inplace;                             
ERROR 1845 (0A000): ALGORITHM=INPLACE is not supported for this operation. Try ALGORITHM=COPY.
MariaDB [test]> ALTER TABLE test_online ADD COLUMN hash VARCHAR(32) AS (md5(handle)) persistent, ADD UNIQUE INDEX hash(hash), algorithm=copy;
Query OK, 3 rows affected (1.11 sec)               
Records: 3  Duplicates: 0  Warnings: 0

MariaDB [test]> SELECT * FROM test_online;
+----+--------+------+----------------------------------+
| id | handle | DATA | hash                             |
+----+--------+------+----------------------------------+
|  1 |     12 |    0 | c20ad4d76fe97759aa27a0c99bff6710 |
|  2 |     54 |    0 | a684eceee76fc522773286a895bc8436 |
|  3 |    546 |    0 | ed265bc903a5a097f61d3ec064d96d2e |
+----+--------+------+----------------------------------+
3 rows in set (0.00 sec)

MariaDB [test]> ALTER TABLE test_online DROP INDEX handle, algorithm=inplace;
ERROR 1845 (0A000): ALGORITHM=INPLACE is not supported for this operation. Try ALGORITHM=COPY.
MariaDB [test]> ALTER TABLE test_online ADD INDEX DATA(DATA), algorithm=inplace;
ERROR 1845 (0A000): ALGORITHM=INPLACE is not supported for this operation. Try ALGORITHM=COPY.
MariaDB [test]> CREATE INDEX DATA on test_online(DATA) algorithm=inplace;
ERROR 1845 (0A000): ALGORITHM=INPLACE is not supported for this operation. Try ALGORITHM=COPY.
MariaDB [test]> ALTER TABLE test_online DROP COLUMN hash, algorithm=inplace;
Query OK, 0 rows affected (0.65 sec)
Records: 0  Duplicates: 0  Warnings: 0

MariaDB [test]> ALTER TABLE test_online DROP INDEX handle, algorithm=inplace;
Query OK, 0 rows affected (0.14 sec)
Records: 0  Duplicates: 0  Warnings: 0

MariaDB [test]> ALTER TABLE test_online ADD INDEX DATA(DATA), algorithm=inplace;
Query OK, 0 rows affected (0.24 sec)
Records: 0  Duplicates: 0  Warnings: 0

MariaDB [test]> ALTER TABLE test_online ADD COLUMN sha VARCHAR(32) AS (sha1(handle)) persistent, algorithm=inplace;
ERROR 1845 (0A000): ALGORITHM=INPLACE is not supported for this operation. Try ALGORITHM=COPY.
MariaDB [test]> ALTER TABLE test_online ADD COLUMN sha VARCHAR(32), algorithm=inplace;
Query OK, 0 rows affected (0.57 sec)
Records: 0  Duplicates: 0  Warnings: 0