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From: Greg Sabino Mullane <htamfids@gmail.com>
Date: Wed, 20 Aug 2025 12:12:25 -0400
Message-ID: <CAKAnmmJfh2hPk8v597tRNVhM9_4oCQmTtJ6CVqHAp4hO0qPj6Q@mail.gmail.com>
Subject: Re: Domains vs data types
To: =?UTF-8?B?RXJ0YW4gS8O8w6fDvGtvZ2x1?= <ertan.kucukoglu@gmail.com>
Cc: pgsql-general@lists.postgresql.org
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On Wed, Aug 20, 2025 at 12:48=E2=80=AFAM Ertan K=C3=BC=C3=A7=C3=BCkoglu <er=
tan.kucukoglu@gmail.com>
wrote:

> Does the second table have any technical advantage/disadvantage over plai=
n
> data type definition?
> Less metadata in memory? High metadata in memory? Less/increased disk
> space?
>

Same disk space. No disadvantage other than confusing your users, and any
performance differences will be so minor as to be unmeasurable. (my two
cents: domains are best when the data type is complex AND shared across
multiple tables. Even then I tend to avoid them.)

Cheers,
Greg

--
Crunchy Data - https://www.crunchydata.com
Enterprise Postgres Software Products & Tech Support

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<div dir=3D"ltr"><div dir=3D"ltr">On Wed, Aug 20, 2025 at 12:48=E2=80=AFAM =
Ertan K=C3=BC=C3=A7=C3=BCkoglu &lt;<a href=3D"mailto:ertan.kucukoglu@gmail.=
com">ertan.kucukoglu@gmail.com</a>&gt; wrote:</div><div class=3D"gmail_quot=
e gmail_quote_container"><blockquote class=3D"gmail_quote" style=3D"margin:=
0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">=
<div dir=3D"ltr"><div>Does the second table have any technical advantage/di=
sadvantage over plain data type definition?</div><div>Less metadata in memo=
ry? High metadata in memory? Less/increased disk space?</div></div></blockq=
uote><div><br></div><div>Same disk space. No disadvantage other than confus=
ing your users, and any performance differences will be so minor as to be u=
nmeasurable. (my two cents: domains are best when the data type is complex =
AND shared across multiple tables. Even then I tend to avoid them.)</div><d=
iv><br></div><div>Cheers,</div></div><div dir=3D"ltr" class=3D"gmail_signat=
ure"><div dir=3D"ltr"><div>Greg</div><div><br></div><div>--</div><div>Crunc=
hy Data - <a href=3D"https://www.crunchydata.com" target=3D"_blank">https:/=
/www.crunchydata.com</a></div><div>Enterprise Postgres Software Products &a=
mp; Tech Support</div><div><br></div></div></div></div>

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