Re: [HACKERS] generated columns

On 15/11/2018 15:10, Robert Haas wrote:
> I don't have a strong position on 1 vs. 2 vs. 3, but I do think it
> would be nicer not to use '\0' as a column value.  I'd suggest you use
> 'n' or '0' or '-' or some other printable character instead.

I had carefully considered this when attidentity was added.  Using '\0'
allows you to use this column as a boolean in C code, which is often
convenient.  Also, there are numerous places where a pg_attribute form
or a tuple descriptor is initialized to all zeroes, which works well for
most fields, and adding one exception like this would create a lot of
extra work and bloat the patch and create potential for future
instability.  Also note that a C char '\0' is represented as '' (empty
string) in SQL, so this also creates a natural representation in SQL.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services