Subject: Re: Docs for Generated Columns
To: Tobias Bussmann <t.bussmann@gmx.net>, pgsql-docs@lists.postgresql.org
References: <071F9108-0335-4309-ACD3-262AF04A1817@gmx.net>
From: Joe Conway <mail@joeconway.com>
Openpgp: preference=signencrypt
Autocrypt: addr=mail@joeconway.com; keydata=
 mQINBEpXMCsBEADDnXUQzjlyi/cX02Gtdy2CLcroE5CsC7DJKdOBDbfgn0kfiIYoV5JniG4l
 VyzZUodY8yUAagqLYolh0UkBzs9N+qkm7erde4ypw3jzVQ37BuzIvk3nMUbuDZDgxWqX+nVS
 sKc+BQ5BpzgCHg48leoRO2ohjvYnUhgH3j2rFZCzaj6qQ7mv+XoxOJmUlVQtG06Jwkk7Vu14
 7U9nMMM6hyUKzVnmCphnlcMNo26UyVU70MwFfFJgcI0c5fpp8byN56eD6VJVnufO5WAuEhzE
 qcrSJR2FAlmM90GBY+6vP29twLDCHuSFvrnujNCx/BvCC/a3/gPvyAFp4JtMm9eXAmq3m/Kw
 94nTJXVdcbQeQQDp3KIG7MmWS4lnGvPn8v0CjgNaLvZXFLo1FgmUVsyEq1Lww4iRLa6sbpXJ
 ESx15UEue1k1YZM9C+4F/o3aeKNsAienjw2EXFzcaxIg/C4P493VMi3Qa8ycVxR5iYhUbYdo
 DFIUQhbFNsYfrtW/qZAELT3FCYFpZYG01e9Hj+cBrXXgyDDkQ5Lq4mlvmkRvuxn61V6Au4HA
 0sJiCox5pM1FvzT+aI8HY1BYaiB9Pl4fhpKgmhhlSuglk9v39S4jmlUIb45iLAUVpeNM6Qjm
 69pf5da9sm4aGFa7YlDSKf/WcU7z9ITZxsilOi2n7YJiwG7kTQARAQABtB9Kb2UgQ29ud2F5
 IDxtYWlsQGpvZWNvbndheS5jb20+iQI8BBMBAgAmAhsDBwsJCAcDAgEGFQgCCQoLBBYCAwEC
 HgECF4AFAlpoksUCGQEACgkQMyt+aLaZQ0p4XQ/9F4WSf4ZFuL3ae356ApVqnLxphHXeXHli
 ePZe7qosvXMQLN9Y2m5cQwqojsQh4pZujIi4Iwxw7ORg6HbMO8dMhyu8TlDavErcgO561hG7
 /TCcCLf5SkadxBqYWAJH09W8S2iC3gQtS+qs4Y7sIvRi881EsPzG5Lrzu7Ei8ufqsSnbLUQk
 zAaKjK3IzAFvzA3VCg/8Aqhf8obhqL0j5I5DNOpAt2U4gkEzIrX1g5xSXpRLMHLEK7hPViY8
 pFQyRvyZioE4hckNsnidCgiv4HefJUFRIVxDkHBeLhTzqTPloesFT/bskhckIS6F4suMx044
 WTTW6UiARuWw3aaBTmxay2rjPCsGaJPawzY0O3HlNlZherCzuBpa+Qk1kMLkcxMlYjCrMgIR
 YyBpIK46ltPQaog4Ujh21w1Z8m/ufG5v/HTuLdXM9hGfTlW7aY6psCAV/MwfycDHLRMc+UY7
 W2cp6DlWQ7GHLP+vzvBcl5Odi04EhcYnHMZjKvRFsxhE0LZcTejrtxPkDgR9G59irlIx1+py
 ziK2B0hs7Er1Yq7qQGQiQGLoglSNDsvsUeyMGyabasmUd5xrRO35SpGv+hyYGAZ3Pyk9Vtxl
 CO7BJkZiV9YSMHp6hOdmYZd4SZRChd9sKd6eSw1xIlBALz1ZHuQVMBuZvuVGFsS81Zqckb/2
 D5q5Ag0ESlcx7QEQAKhm5UhGfbe3hM4yCaa/pPaNaswlB2tK1DHAjDlDm7gDVEodfsrvAFUU
 unLodlvCd0g/GpLmXXdROU/I+HusVqQhDbVeHMwO2VUVHamRWqDfrCjMYVxLz80d96TYyeyW
 6RUNkJmXJAOKgy8veI7Z1F+j1gXQR7UlzonnSkWbs0oQ3RglvyqhkUzWtXU7F+j2hQ2vQsct
 Lnq3lYo0bYkZ3K6RyKZXSly9Hd7DzYkMzz7StNRlyeQJxplPrVPup7N8SqDrI126sq0cwdUB
 Gn1sKVoO+bGidBjhJgxouNPkMJlPjbKOgb7tv5ZnM33FGXNdC5sPKoZ4mC+gaqRHYaH/V61v
 fCo1CYNLIK+Cj+Oua8mQ6CPeOb5VKcJ0JM96eGNlzF9EawppOG7xCDcbmBEr0m1go9MHEUel
 0L1i8RSDYOHQQkLT2MVWYf4UsRlEGbME+kF7DEX9Fvie7qglFTXC2d+YVN73AnXcoM/IYUOR
 DXjVVaqQoHuA4uxwJ31o/rEaOihr2yCScr8mB8J3b3KyNfuCBm5gN0tUQw+t5szMYurDpZ1G
 L4O7btaQ5u4iJMfRTCnPrzW+wkdVrao7AmRNWEtSlXsycClKFCHz/Ej5rpXOKSp+a/xcaFX1
 v2eS/+Ujp5ESu9p57JwlP6aSqYBiOALRJXZ9DVtZL96okjzXjrd7ABEBAAGJBD4EGAEIAAkF
 AkpXMe0CGwICKQkQMyt+aLaZQ0rBXSAEGQEIAAYFAkpXMe0ACgkQN/L3QzX32GV1Jw//fhvL
 Mk1YNS/2N5jc5HYmEjcL2OWBLLrO5RMCaOgCNmYsepkigy2U+GSloVy8Y40/UfYzIoNf1DiB
 Qyj5Ipa4eMjfKA7+1q43a5wkDDWogFNflKTTNemwrHDKR1WWDrxt8uAgJdlBGDQA7A0q3D2i
 Xhd7ALLOHhuXDY1++N9TK9KMfV90Oay0mIMLQhTG/UgsgrYYb78H2pk8XMYZY29vgZlj9VH2
 f1RpOoh7lCaB+2glN27Rzh17q0/zEjwXk4sDyYHRIycaqnM4ozSnliXyoWM5bvmqSGBCm5jl
 BjNW+cFbFy15U595AIXXiUXl8hsTF2JWwgHr+hYdtoEH3oEOxzM18ENXKTTgN+BafdMsah4e
 HIcVvrVrH6rlsPwCvk3o/PJ07qVbUW+dbZG8UB1JwqUUqGhrCk87kztajlvZGZWxWDSB4Lnb
 T6Jc0L7/YXG8U3sJ2OtZ95Lal5XfNo0yBdPflmalH3xf/EcxaYFETbDrY5UgEVa2HBw8XzKk
 rTbM8rD318M+jBOuL6o3cGMOeFOm4C51fJZmOCFd03LhMkoj9IbLIPGKosIBsxb7zP5YLAbI
 b3el6pvo9CKtNuR+IcVOoFtH+KVOxGsbbxFEFbsAmPMreF1hIv+l+HXBaDhUkaUmpJ1Mhxol
 aM6O/LGG4VQV7wBQFunVaN8EPqMqYDph3A//TjQVd8fqvw5Ezj1958IUmV0jxeGX2m/fspGh
 njF+6Adx3PFbZoKyW71cA/TnlHVYCaizjYYRNMC3g5VFytOYOZFi0GKsxQTX5PcPhDjFFTUv
 FVVZwDYUK3QlC+wGDTeNWfAJIZnTPPIXSiHzh3si+ngKjE+ngcRF1VY5K4xvc6ss6uq8kI8L
 Ct+TpOMr99ijaYEbMZ8WJagynD5BLNYxpP6CCTMDi1Xqydg0E/mhR9w9aUOvdTZw1OOKtLnz
 B1E0wFbzJXEvjP2eEVNlStS5RTawFDpqxGwXJcHqe8qtg8B+C1r47RmHnKKm+DTOPFQWTj83
 l775aNMzAHm+Pr1TdSA5XRyQ3wxwYKfhp1suKhILUZLjbiCQf92RZQ6yEdXskMr2A4n0GQWq
 Q8k7r9QPqtUP7lsiyyDem7r9h5mAm94r3Td22L3JaSHkBD+4jC4gIXeYoyd+lTz/zYOx0Fri
 J8dXHalmyTGsSxV7FXv1/thVEf6R7TDdVwhqf/WL3uWTmVBR0tJscG+9iCVch/OG/uCDkWZQ
 sOTotqj6f5jSZI+NOUqt62+8i8gjYEa7zRZ2HXFOTV8UduCjheWB2VCUj5EjFjTMjfTVkyZ5
 SiFht7bM5l/odoYU6vn37/5s/ZsMTZX1zG5oXv6iULrHLYHhUxR93FlVyn4DiHsWND/Idj65
 Ag0ESlcyJwEQAOkTBb9yDhJbMUgvhM11rZwT5tm4Y9TqtEHn0Zy3t9g7bdFFpMvav/KENd3o
 AtLFpMDf+H3AggFk4ftUwJwiVgJ88ilvCynJUGXiuYIaexY4DLgn4xpnuiEpYEFVdWnlw7dW
 VTc62exfqIz9bSWRzwfBCY9ruYGEb4RDPDSNSAVyI7sxHzef2asiYxIcxrTrw5VugWNlPZcV
 5/EJ6PUvATjBF2TBkXV7KOciQng2tsQGrGMkY5mduNqwpuh6zfPcVF8LeObe96wv5ZhPRpO7
 9nef7hnK2lJogp3JIo558Jlbz9WHtQEMZR85+bUhtI825QyNAFz3Jrn7NMgvDikc2OrWo7YM
 gMC5hDSWVFqA6/EQCNnDWGABWgeYHZFpnPwsvUWIYdhSilUuj/Tuzvz9ZmucFNbQbauDQw6V
 Q38ofGnoYDZFJsGncprB8dBi4tDrIQ+1RlIh6C2Z/eMipqJOT26+spluTjouvnKT0S5yOgyX
 0PjbsysgwQdCGNJLHOjhHbSpSmOLaduV3CQo/0+DHT/TBjYfIXjTWouY9TkGxG4eNrxU0u2x
 Ay5bMqOPmsFdjLTWlQUlF/fTMhB54XwI3FHWgnSnXZzStDTmTebLNdT/ftgliAzA81uMj49j
 0exv731/v+7udLA1bV8gnZ01zQCASDpWiRQR3fgwcugSUqgRABEBAAGJAh8EGAEIAAkFAkpX
 MicCGwwACgkQMyt+aLaZQ0pwAQ//bjcWnZg/jjRQ9gbZUGMqniItZYRglBMKIqt4Fia379Jm
 HwTvavnFkJ8XMZ56UB0FIrgS+sUkRH6cPRQR+7Qi392LD021DXgSsz9CwFHjFyBGHwLEOTRc
 fYQbtJy0shHDJB4aQTOX3ERDH1PsvJNuevmQMzS0DWFav9+xMz9rKP4N+HffoBIZE0C1xIE4
 3nD4eLsbycte9sVIrmlNuUti3qUxJAQw8HwfJ6ZbBInHxquApR16uD1u99o6XlndFrDlY22t
 RmHCM0bR81GfGNdcU3Uo+rG/R/k4qa7s9/dgKvMbyH3fHhp/ceKag80Xo8IFurRl0ZJP3sHJ
 2QDHCVLat7jRZ+43hi1WlIhFbrgn6IyI0i7XR/W8JjrC5MsKq4TUwGH077sU/kcHYebVJZRb
 UUst2hAGHDFVBcG12qoKf+ltL9qXJc1y7BGeCoUW6QjOpljpq6ZL4FQUsM0RSRjs5egE3szP
 cIf5SyPK6WDOApoAq6M7BBFMGDZwEylYMtr0YekA1u86UA9D2xwLHEbBBp/uiby1c9JbPJ1P
 n8zJP8WZNeRw4Q9TtqVK09+oLirMUSpIDd6KdZ1VgRxOK2re7tjDvkVuYsSrsiJ+1iJNEnp9
 iK0ok0DlJpSCe6KhkxpaTdeoWMXdKuJWec0NIqoAd54ZgBPnr+UPxTixgPq/p6Q=
Message-ID: <9997d7e0-b0d9-1ec5-365d-153b58ad533e@joeconway.com>
Date: Fri, 24 May 2019 08:21:57 -0400
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.6.1
MIME-Version: 1.0
In-Reply-To: <071F9108-0335-4309-ACD3-262AF04A1817@gmx.net>
Content-Type: multipart/signed; micalg=pgp-sha512;
 protocol="application/pgp-signature";
 boundary="7h5DzYcR0GYqKMETB8JxL8TTUZ39vVzqk"
Precedence: bulk

This is an OpenPGP/MIME signed message (RFC 4880 and 3156)
--7h5DzYcR0GYqKMETB8JxL8TTUZ39vVzqk
Content-Type: multipart/mixed; boundary="FvwEWSeKvsR6nCGjEETmH7tHgnau6VlAq";
 protected-headers="v1"
From: Joe Conway <mail@joeconway.com>
To: Tobias Bussmann <t.bussmann@gmx.net>, pgsql-docs@lists.postgresql.org
Message-ID: <9997d7e0-b0d9-1ec5-365d-153b58ad533e@joeconway.com>
Subject: Re: Docs for Generated Columns
References: <071F9108-0335-4309-ACD3-262AF04A1817@gmx.net>
In-Reply-To: <071F9108-0335-4309-ACD3-262AF04A1817@gmx.net>

--FvwEWSeKvsR6nCGjEETmH7tHgnau6VlAq
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: quoted-printable

On 5/23/19 5:50 PM, Tobias Bussmann wrote:
> while reading though the docs of the upcoming pg12 features, I
> stumbled upon some wording regarding generated columns: both in
> create_table.sgml [1] and create_foreign_table.sgml [2] the paragraph
> for the GENERATED ALWAYS AS clause is introduced with
>> This clause creates the column as a generated column. The column
>> cannot be written to, and when read it will be computed from the
>> specified expression.

> To me this sounds confusing, if not wrong. Till v8 of the patch were
> STORED and VIRTUAL generated columns were described afterwards this
> was less obvious but now with only STORED it sounds like a reference
> to the VIRTUAL variant.

No doubt this is flat out wrong.


> Not being I native english speaker I'm restrained to send a patch but
> may I suggest the following for discussion:

> The column cannot be written to, and when read the result of the
> specified expression will be returned.


That sounds reasonable to me.

Joe

--=20
Crunchy Data - http://crunchydata.com
PostgreSQL Support for Secure Enterprises
Consulting, Training, & Open Source Development


--FvwEWSeKvsR6nCGjEETmH7tHgnau6VlAq--

--7h5DzYcR0GYqKMETB8JxL8TTUZ39vVzqk
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename="signature.asc"

-----BEGIN PGP SIGNATURE-----
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=4W7O
-----END PGP SIGNATURE-----

--7h5DzYcR0GYqKMETB8JxL8TTUZ39vVzqk--