From: John Lumby <johnlumby@hotmail.com>
To: "pgsql-docs@lists.postgresql.org" <pgsql-docs@lists.postgresql.org>
CC: "David G. Johnston" <david.g.johnston@gmail.com>, Tom Lane
	<tgl@sss.pgh.pa.us>
Subject: Re: description of Aggregate Expressions
Thread-Topic: description of Aggregate Expressions
Thread-Index: AQHVq8Cfp39padbrW02rHVPPdQZZdaetcyGAgAAI/4CAAAlrqw==
Date: Fri, 6 Dec 2019 20:01:14 +0000
Message-ID: 
 <DM6PR06MB5562ED9060C811718CC59605A35F0@DM6PR06MB5562.namprd06.prod.outlook.com>
References: 
 <2A91BEF8171A5349931391E0C721CC5375705457@CPEMS-KPN501.KPNCNL.LOCAL>
 <251962385fdc49da0da54e22588aabd6fbc2e0fa.camel@osdev.nl>
 <2A91BEF8171A5349931391E0C721CC53757054D3@CPEMS-KPN501.KPNCNL.LOCAL>
 <2CB4B3C9-F43F-49D8-A594-93DBE99EF514@elevated-dev.com>
 <7308f0f3a1674a39bada8571189a3735@CPEMS-KPN509.KPNCNL.LOCAL>
 <91CEBEAA-7260-4503-832F-E5B27B91BE1F@elevated-dev.com>
 <2A91BEF8171A5349931391E0C721CC5375705528@CPEMS-KPN501.KPNCNL.LOCAL>
 <E813B7F6-B641-4739-A209-F0352A780EF8@elevated-dev.com>
 <2A91BEF8171A5349931391E0C721CC53757055C3@CPEMS-KPN501.KPNCNL.LOCAL>
 <DM6PR06MB55622DFEE2755236B8A810A0A35C0@DM6PR06MB5562.namprd06.prod.outlook.com>
 <CAKFQuwZk3Kt4uNktMgLYj5B1Rzrm1R4EMVZQRka189AhnPkM=Q@mail.gmail.com>
 <DM6PR06MB55621D8E8B9C786DAA6BA077A35F0@DM6PR06MB5562.namprd06.prod.outlook.com>,<382.1575659855@sss.pgh.pa.us>
In-Reply-To: <382.1575659855@sss.pgh.pa.us>
Accept-Language: en-CA, en-US
Content-Language: en-CA
x-ms-exchange-messagesentrepresentingtype: 1
x-tmn: [IUIbB7JOfetIVPr6ckD7Djur/Zo9mCk1]
x-ms-publictraffictype: Email
x-incomingheadercount: 46
x-eopattributedmessage: 0
x-ms-office365-filtering-correlation-id: 87eb27a5-3512-408e-a78f-08d77a870cb4
x-ms-traffictypediagnostic: SN1NAM01HT005:
x-microsoft-antispam: BCL:0;
x-microsoft-antispam-message-info: 
 66Pzzjyjxrrr18yyJk09hEMjeaA11HQ6drNBOiulXF0FD6YM0jpYXzPkuVIjhm+dyb9QkjKp3zp5RUXhzg6em05tqX6QusmIUIj9JZQkZSh05kANG1Sba3UII9cHoPqwNjmHuuGg69K2o7s/UtPNTRsImK36ZLCF7dHukDyFjF1IvWraAGbOoF2AhiDguFm2
x-ms-exchange-transport-forked: True
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-OriginatorOrg: hotmail.com
X-MS-Exchange-CrossTenant-RMS-PersistedConsumerOrg: 
 00000000-0000-0000-0000-000000000000
X-MS-Exchange-CrossTenant-Network-Message-Id: 
 87eb27a5-3512-408e-a78f-08d77a870cb4
X-MS-Exchange-CrossTenant-rms-persistedconsumerorg: 
 00000000-0000-0000-0000-000000000000
X-MS-Exchange-CrossTenant-originalarrivaltime: 06 Dec 2019 20:01:14.7824
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Internet
X-MS-Exchange-CrossTenant-id: 84df9e7f-e9f6-40af-b435-aaaaaaaaaaaa
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN1NAM01HT005
List-Id: <pgsql-docs.lists.postgresql.org>
List-Help: <https://lists.postgresql.org/manage/>
List-Subscribe: <https://lists.postgresql.org/manage/>
List-Post: <mailto:pgsql-docs@lists.postgresql.org>
List-Owner: <mailto:pgsql-docs-owner@lists.postgresql.org>
List-Archive: <https://www.postgresql.org/list/pgsql-docs>
Precedence: bulk

Tom Lane wrote=0A=
=0A=
> > How about replacing "expression [ , ... ]" =A0by "parameter_list" in th=
e description, =0A=
> > and then stating that parameter_list can be either a single expression =
or , =0A=
> > =A0if the particular aggregate function accepts it (for which, =A0 cons=
ult that function's reference),=0A=
> > =A0 a comma-separated list of expressions.=0A=
> =0A=
> That's just as wrong. =A0As we tried to explain before, the=0A=
> parenthesized-list syntax is a row constructor, so it only works=0A=
> in cases where the aggregate function can accept a composite=0A=
> argument type. =A0Most don't.=0A=
>=0A=
=0A=
But surely not *all* cases of a multi-expression parameter list of an aggre=
gate function are row constructors are they?=A0 =A0=A0What about=0A=
=0A=
select parent_id, name, GROUPING(parent_id , name), count(*) FROM mytable G=
ROUP BY ROLLUP(parent_id , name);=0A=
=0A=
In the piece "GROUPING(parent_id , name)" ,=0A=
  is "(parent_id , name)"  a row constructor or a list of two expressions?=
=0A=
=0A=
Or are you saying those are one and the same thing?=0A=
=0A=
Cheers,   John=