create table t1 (ts timestamp time index default CURRENT_TIMESTAMP);

Affected Rows: 0

show create table t1;

+-------+-----------------------------------------------------------+
| Table | Create Table                                              |
+-------+-----------------------------------------------------------+
| t1    | CREATE TABLE IF NOT EXISTS "t1" (                         |
|       |   "ts" TIMESTAMP(3) NOT NULL DEFAULT current_timestamp(), |
|       |   TIME INDEX ("ts")                                       |
|       | )                                                         |
|       |                                                           |
|       | ENGINE=mito                                               |
|       |                                                           |
+-------+-----------------------------------------------------------+

create table t2 (ts timestamp time index default currEnt_tImEsTamp());

Affected Rows: 0

show create table t2;

+-------+-----------------------------------------------------------+
| Table | Create Table                                              |
+-------+-----------------------------------------------------------+
| t2    | CREATE TABLE IF NOT EXISTS "t2" (                         |
|       |   "ts" TIMESTAMP(3) NOT NULL DEFAULT current_timestamp(), |
|       |   TIME INDEX ("ts")                                       |
|       | )                                                         |
|       |                                                           |
|       | ENGINE=mito                                               |
|       |                                                           |
+-------+-----------------------------------------------------------+

create table t3 (ts timestamp time index default now());

Affected Rows: 0

show create table t3;

+-------+---------------------------------------------+
| Table | Create Table                                |
+-------+---------------------------------------------+
| t3    | CREATE TABLE IF NOT EXISTS "t3" (           |
|       |   "ts" TIMESTAMP(3) NOT NULL DEFAULT now(), |
|       |   TIME INDEX ("ts")                         |
|       | )                                           |
|       |                                             |
|       | ENGINE=mito                                 |
|       |                                             |
+-------+---------------------------------------------+

create table t4 (ts timestamp time index default now);

Error: 1001(Unsupported), Unsupported expr in default constraint: Identifier(Ident { value: "now", quote_style: None }) for column: ts

drop table t1;

Affected Rows: 0

drop table t2;

Affected Rows: 0

drop table t3;

Affected Rows: 0