auto_random metaphors the column be PK but has no way to be clustered

[lysu]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

create table t(a bigint key auto_random(5));

2. What did you expect to see? (Required)

create table t that a be clustered primary key

3. What did you see instead (Required)

ERROR 8216 (HY000): Invalid auto random: column a is not the integer primary key, or table is created with alter-primary-key enabled

4. What is your TiDB version? (Required)

master

[lysu]

user can work around by change ddl to

create table t(a bigint key primary key clustered auto_random(5));

it's low priority to fix this, just mark

[tangenta]

So the expected behavior is that auto_random implies clustered?

[lysu]

So the expected behavior is that auto_random implies clustered?

@bb7133 @coocood how do you think about this?