Hi All,
The difference in how format handles `regclass` and `name` seems like an
inconsistency:
WITH conversions(casts, format, result) AS (
VALUES (ARRAY['name']::regtype[], '%I', format('%I',
name('select'))),
(ARRAY['name']::regtype[], '%L', format('%L',
name('select'))),
(ARRAY['name']::regtype[], '%s', format('%s',
name('select'))),
(ARRAY['regclass']::regtype[], '%I', format('%I',
regclass('select'))),
(ARRAY['regclass']::regtype[], '%L', format('%L',
regclass('select'))),
(ARRAY['regclass']::regtype[], '%s', format('%s',
regclass('select'))),
(ARRAY['regclass', 'name']::regtype[], '%I', format('%I',
name(regclass('select')))),
(ARRAY['regclass', 'name']::regtype[], '%L', format('%L',
name(regclass('select')))),
(ARRAY['regclass', 'name']::regtype[], '%s', format('%s',
name(regclass('select'))))
) SELECT * FROM conversions;
casts | format | result
-----------------+--------+--------------
{name} | %I | "select"
{name} | %L | 'select'
{name} | %s | select
{regclass} | %I | """select"""
{regclass} | %L | '"select"'
{regclass} | %s | "select"
{regclass,name} | %I | """select"""
{regclass,name} | %L | '"select"'
{regclass,name} | %s | "select"
My assumption is that they both represent valid SQL identifiers, so it stands
to reason that `%I` should result in a valid identifier for both of them (or
neither one).
All three of the %I results are valid identifiers.
regclass performs the same conversion that %I performs. But since the output of the regclass conversion is a valid identifier, with double-quotes, the %I adds another pair of double-quotes and doubles-up the existing pair thus leaving you with 6.
<select> is a reserved word and thus can only be used as an identifier if it is surrounded in double-quotes. name() doesn't care (not that it is user-documented that I can find) about making its value usable as an identifier so when its output goes through %I you get the expected value.
If you are going to use regclass you want to use %s to insert the result into your string; not %I.
David J.
