Re: Proposal: variant of regclass

> Tatsuo Ishii <ishii(at)postgresql(dot)org> writes:
>> Can I make sure that we want to keep the current behavior:
>
>> test=# SELECT 'pg_klass'::regclass;
>> ERROR: relation "pg_klass" does not exist
>
> Yeah, I think the consensus is to not change the behavior of the input
> functions, just add some new ones.

Ok, here is the conceptual patch to implement "toregclass" (only for
now). If my direction is ok, I'll come up with complete patches to
implement more "to*" functions. Any advice will be appreciated.

Here is a sample session:

test=# select toregclass('foo');
toregclass
------------
-
(1 row)

test=# select toregclass('pg_class');
toregclass
------------
pg_class
(1 row)

test=# select toregclass('pg_class')::oid;
toregclass
------------
1259
(1 row)

test=# select toregclass('foo')::oid;
toregclass
------------
0
(1 row)

Implementation notes:

To implement toregclass, which does not throw errors when invalid
argument is given, src/backend/utils/adt/regproc.c is modified. I
added two static functions:

static Datum regclass_gut(char *class_name_or_oid, bool raiseError);
static List *stringToQualifiedNameList_gut(const char *string, bool raiseError);

regclass_gut is called from regclassin and toregclass and do the most
job before regclassin did. "raiseError" flag controls whether an error
is raised or not when an invalid argument (for example non existent
relation) is given. For this purpose, regclass_gut wraps the call to
oidin using a PG_TRY block.

Secondly, when called as bootstap and raiseError is true, returns
InvalidOid instead of raising an error "relation XXX does not
exist". However, I doubt there's no customer who calls regclass_gut
with raiseError is false in the bootstrap.

Thirdly, stringToQualifiedNameList_gut is added to replace
stringToQualifiedNameList. The reason why I don't use PG_TRY block is,
I need to free some memory allocated inside the function in an
error condition.

Finially I modified the call to RangeVarGetRelid to switch
"missing_ok" flag to reflect raiseError argument.

One thing I need to further is modifying makeRangeVarFromNameList. If
strange schema qualified name like "a.b.c.d.e.f" is given, still an
error raises.

So, any advice will be appreciated.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp