I came here to determine how much storage a boolean variable uses

On Sun, Aug 29, 2021 at 11:59 PM PG Doc comments form <
noreply@postgresql.org> wrote:

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/13/datatype.html
Description:

I'd like to see a fourth column added to Table 8-1 that contains the size
or
size range of the data type.

I would argue this is sufficiently provided by the pg_attribute catalog's
attlen and attalign fields, as pointed to on the same page linked below.

Maybe a note about the amount of space in the

row that a NULL column uses vs a NOT NULL.

Implementation detail that is covered in the internals section:

https://www.postgresql.org/docs/current/storage-page-layout.html#STORAGE-TUPLE-LAYOUT

David J.

On 8/30/21 11:31 AM, David G. Johnston wrote:

On Sun, Aug 29, 2021 at 11:59 PM PG Doc comments form
<noreply@postgresql.org <mailto:noreply@postgresql.org>> wrote:

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/13/datatype.html
<https://www.postgresql.org/docs/13/datatype.html&gt;
Description:

I'd like to see a fourth column added to Table 8-1 that contains the
size or
size range of the data type.

I would argue this is sufficiently provided by the pg_attribute
catalog's attlen and attalign fields, as pointed to on the same page
linked below.

Maybe a note about the amount of space in the
row that a NULL column uses vs a NOT NULL.

Implementation detail that is covered in the internals section:

https://www.postgresql.org/docs/current/storage-page-layout.html#STORAGE-TUPLE-LAYOUT
<https://www.postgresql.org/docs/current/storage-page-layout.html#STORAGE-TUPLE-LAYOUT&gt;

Well, it is provided one level deeper in the data type docs, e.g.:

https://www.postgresql.org/docs/13/datatype-boolean.html

I think it's a reasonable request to consider. It potentially duplicates
the info in the data types section (i.e. one more thing to maintain),
but it does provide some convenience for scanning it across the
consolidated table.

Jonathan

On Mon, Aug 30, 2021 at 12:16:13PM -0400, Jonathan Katz wrote:

https://www.postgresql.org/docs/current/storage-page-layout.html#STORAGE-TUPLE-LAYOUT
<https://www.postgresql.org/docs/current/storage-page-layout.html#STORAGE-TUPLE-LAYOUT&gt;

Well, it is provided one level deeper in the data type docs, e.g.:

https://www.postgresql.org/docs/13/datatype-boolean.html

I think it's a reasonable request to consider. It potentially duplicates
the info in the data types section (i.e. one more thing to maintain),
but it does provide some convenience for scanning it across the
consolidated table.

FYI, I usually use psql's \dTS+.

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

If only the physical world exists, free will is an illusion.