Re: [HACKERS] Name type vs. char *

> We currently use Name sometimes, and char* other times to store
> relation, attribute, type, and view names.
>
> One thing Mariposa did was to make that more consistent, so you passed
> around Name(NameData pointers) instead of the more generic char *.
> However, the Name fields behave like char*, but are clearer.
>
>     typedef struct nameData
>     {
>         char        data[NAMEDATALEN];
>     } NameData;
>     typedef NameData *Name;
>
> Do people see value in making this switch?  Would take me a few hours to
> make the change.

I have decided I don't even like this change.  The confusion is because
of the on-disk name storage vs. query-supplied names.  I will add this
to the developers FAQ.  This has confused me, so I assume others may be
confused about the distinction.

Comments?

---------------------------------------------------------------------------

Why are table, column, type, function, view names sometimes referenced
as Name or NameData, and sometimes as char *?

Table, column, type, function, and view names are stored in system
tables in columns of type Name.  Name is a fixed-length, null-terminated
type of NAMEDATALEN bytes.  (The default value for NAMEDATALEN is 32
bytes.)

    typedef struct nameData
    {
        char        data[NAMEDATALEN];
    } NameData;
    typedef NameData *Name;

Table, column, type, function, and view names that come in to the
backend via user queries are stored as variable-length, null-terminated
character strings.

Many functions are called with both types of names, ie. heap_open().
Because the Name type is null-terminated, it is safe to pass it to a
function expecting a char *.  Because there are many cases where on-disk
names(Name) are compared to user-supplied names(char *), there are many
cases where Name and char * are coerced to match each other.


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