Re: WHERE col = ANY($1) extended to 2 or more columns? - Mailing list pgsql-general

From David G. Johnston
Subject Re: WHERE col = ANY($1) extended to 2 or more columns?
Date
Msg-id CAKFQuwa20KW+Lza0NrOXTQxcpFJRQG=zjwz4LkB9u7DXxEHkBg@mail.gmail.com
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In response to Re: WHERE col = ANY($1) extended to 2 or more columns?  (Alban Hertroys <haramrae@gmail.com>)
Responses Re: WHERE col = ANY($1) extended to 2 or more columns?  (Dominique Devienne <ddevienne@gmail.com>)
List pgsql-general
On Thu, Feb 9, 2023 at 9:28 AM Alban Hertroys <haramrae@gmail.com> wrote:

> On 9 Feb 2023, at 16:41, Dominique Devienne <ddevienne@gmail.com> wrote:
>
> Hi. We are implementing an API which takes a list of row keys, and must return info about those rows. To implement that efficiently, in as few round-trips as possible, we bind a (binary) array of keys (ints, uuids, or strings) and that works great, but only if the key is a scalar one.
>
> Now we'd like to do the same for composite keys, and I don't know how to do that.
> Is it possible? Could someone please help out or demo such a thing?
> We are doing it in C++ using libpq, but a pure SQL or PL/pgSQL demo would still help (I think).

This works:

=> select (1, 'one'::text) in ((1, 'two'::text), (2, 'one'::text), (1, 'one'::text), (2, 'two'::text));
 ?column?
----------
 t
(1 row)


But you cannot write the right-side of the IN as a single parameter which seems to be the primary constraint trying to be conformed to.

David J.

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