Re: Undocumented array_val[generate_series(...)] functionality? - Mailing list pgsql-general

From David Rowley
Subject Re: Undocumented array_val[generate_series(...)] functionality?
Date
Msg-id CAApHDvoRcyDFvvt+5Y3uNeuckaNhpLZg6jsBc2T3xWqL5iPAnQ@mail.gmail.com
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In response to Undocumented array_val[generate_series(...)] functionality?  ("David G. Johnston" <david.g.johnston@gmail.com>)
Responses Re: Undocumented array_val[generate_series(...)] functionality?
List pgsql-general
On Mon, 12 Jul 2021 at 11:52, David G. Johnston
<david.g.johnston@gmail.com> wrote:
> A post over in Reddit had an expression form I've never seen before:
>
> select (array[1,2,3,4]::integer[])[generate_series(1, 3)];

> Looking at subscripting in the SQL syntax this example doesn't seem to be documented.
>
> https://www.postgresql.org/docs/current/sql-expressions.html#SQL-EXPRESSIONS-SUBSCRIPTS
>
> Is it documented somewhere else, and, regardless, shouldn't it be documented in the linked location?

Isn't this implied by "Each subscript is itself an expression"?
There's nothing special here with the SRF. That just produces 3 rows
and passes the subscript as 1, 2 then 3.

David



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