From: Giacomo Cavalieri <giacomo.cavalieri@icloud.com>
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Subject: Figure out nullability of query parameters
Message-Id: <4915B05B-90B6-4CC2-86E7-EF7C1E2E38C9@icloud.com>
Date: Fri, 27 Jun 2025 16:30:41 +0200
To: pgsql-general@lists.postgresql.org
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Hello!
I=E2=80=99m Giacomo, I=E2=80=99m the maintainer of =
<https://github.com/giacomocavalieri/squirrel>, a tool that can generate =
type safe bindings to run and decode the results of Postgres queries. It =
does that by implementing the extended query protocol, which, among =
other things, returns the OIDs of the query parameters=E2=80=99 types.
This is really handy and has worked great so far but I=E2=80=99m running =
into some rough edges when it comes to the nullability of query =
parameters.

Take a query like this one:
```
insert into some_table(not_null_col, nullable_column)
values ($1, $2)
```
It would be really handy to know that `$1` is being used as a non =
nullable value, while `$2` could actually be null. Can this already be =
achieve today, or would there be a way to surface this kind of =
information for query parameters in the extended protocol?

Sorry if this is not the proper list, I=E2=80=99m very new to all of =
this :)
Thanks!

Giacomo=

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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; =
charset=3Dutf-8"></head><body style=3D"overflow-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: =
after-white-space;">Hello!<div>I=E2=80=99m Giacomo, I=E2=80=99m the =
maintainer of &lt;<a =
href=3D"https://github.com/giacomocavalieri/squirrel">https://github.com/g=
iacomocavalieri/squirrel</a>&gt;,&nbsp;a tool that can generate type =
safe bindings to run and decode the results of Postgres queries. It does =
that by implementing the extended query protocol, which, among other =
things, returns the OIDs of the query parameters=E2=80=99 =
types.</div><div>This is really handy and has worked great so far but =
I=E2=80=99m running into some rough edges when it comes to the =
nullability of query parameters.</div><div><br></div><div>Take a query =
like this one:</div><div>```</div><div>insert into =
some_table(not_null_col, nullable_column)</div><div>values ($1, =
$2)</div><div>```</div><div>It would be really handy to know that `$1` =
is being used as a non nullable value, while `$2` could actually be =
null. Can this already be achieve today, or would there be a way to =
surface this kind of information for query parameters in the extended =
protocol?</div><div><br></div><div>Sorry if this is not the proper list, =
I=E2=80=99m very new to all of this =
:)</div><div>Thanks!</div><div><br></div><div>Giacomo</div></body></html>=

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