Date: Tue, 12 Jul 2022 14:46:14 -0400
From: Bruce Momjian <bruce@momjian.us>
To: Michael Meskes <meskes@postgresql.org>
Cc: "ideriha.takeshi@fujitsu.com" <ideriha.takeshi@fujitsu.com>,
	"'pgsql-docs@lists.postgresql.org'" <pgsql-docs@lists.postgresql.org>
Subject: Re: No documentation exists about ecpg ORACLE comptaible mode
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On Tue, Jul 12, 2022 at 10:20:08AM +0200, Michael Meskes wrote:
> On Sat, Jul 09, 2022 at 09:15:52PM -0400, Bruce Momjian wrote:
> > This is a very good point.  I have studied the issue and created the
> > attached patch to document Oracle-compatibility mode.
> > ...
> 
> Looks good to me. Thanks a bunch Bruce.

Great, thanks.

> I wonder if we should also mention somewhere that some other Oracle
> compatibility features are enable in all modes, like a slightly different
> CONNECT syntax.

Good question.  We support syntax from other databases, only sometimes
with documentation.  I think the rules we use are that we document
compatibility-only behavior when it is useful and obviously if it is
turned in by an option.

In contrast, look at this from backend/parser/gram.y:

	/* INOUT is SQL99 standard, IN OUT is for Oracle compatibility */
	arg_class:  IN_P                                { $$ = FUNC_PARAM_IN; }
	            | OUT_P                             { $$ = FUNC_PARAM_OUT; }
	            | INOUT                             { $$ = FUNC_PARAM_INOUT; }
	            | IN_P OUT_P                        { $$ = FUNC_PARAM_INOUT; }
	            | VARIADIC                          { $$ = FUNC_PARAM_VARIADIC; }

We don't document "IN OUT" anywhere, we just support it silently for
Oracle compatibility, and I am guessing your ecpg connection syntax is
similar.  I think this is done so we don't confuse people with syntax
that has not value unless they are coming from another database. 
Therefore, I don't think we should document it, but I would be
interested to hear if anyone disagrees.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  Indecision is a decision.  Inaction is an action.  Mark Batterson