typeof(varchar): Velox needs to output the length of the varchar as Presto does

[peterenescu]

Description

When outputting the type of a string, Velox omits the length of the string, while Presto doesn't. We should follow Presto's model and output the length of the string too for feature parity. The fix is indeed trivial but will cause the fuzzer to fail.

Error Reproduction

Presto:

presto> SELECT typeof(c0) from (values ('four')) t(c0);
   _col0    
------------
 varchar(4) 
(1 row)

Velox:

presto:di> SELECT typeof(c0) from (values ('four')) t(c0);
  _col0               
---------
 varchar 
(1 row)

Relevant logs

[x-Tong]

I will try it.

[aditi-pandit]

@peterenescu, @x-Tong : Velox doesn't support varchar(n) type only varchar with unlimited length. So that's the current behaviour.

@czentgr has been doing a lot of work for varchar(n) and has some PRs already for it. Lets collaborate on it.

[x-Tong]

got it