Creating a composite type with "char"?

Question

PostgreSQL has a type called char that's stored as an signed 1 byte int

The type "char" (note the quotes) is different from char(1) in that it only uses one byte of storage. It is internally used in the system catalogs as a simplistic enumeration type.

Can we create composite types with "char"? I can create a table with it...

CREATE TABLE pixel ( r "char", g "char", b "char" );

Internally that creates a type which I can use elsewhere,

CREATE TABLE f ( mypixel pixel );

But, can I create a simple TYPE (no table) from it?

CREATE TYPE pixel ( r "char", g "char", b "char" );
ERROR:  syntax error at or near ""char""
LINE 1: CREATE TYPE pixel ( r "char", g "char", b "char" );

Answer 1

It's just the missing keyword AS:

CREATE TYPE pixel AS (r "char", g "char", b "char");

The data type "char" is a non-standard type, primarily meant for internal purposes. But it's just another type - except for the peculiar spelling of the name including the double-quotes to disambiguate against char. See:

• Any downsides of using data type "text" for storing strings?