Re: BUG #18774: Not the required output of the query used in the function(delete_from_table1) in postgresql9.4

David G. Johnston <david.g.johnston@gmail.com>

From: "David G. Johnston" <david.g.johnston@gmail.com>
To: Rajni Bobal <rajnibobal@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Vik Fearing <vik@postgresfriends.org>, pgsql-bugs@lists.postgresql.org
Date: 2025-01-22T16:43:07Z
Lists: pgsql-bugs
You seem to have reversed which query you deem correct...

On Wed, Jan 22, 2025 at 8:59 AM Rajni Bobal <rajnibobal@gmail.com> wrote:

>
>         || quote_ident(colname)
>         || ' IN (SELECT '
>         || quote_ident(colname)
>         || ' FROM '
>         || quote_ident(sel_tblname)
>

This deletes rows from the table depending upon finding the same value in
colname in the subquery.


>         ' where $1 in (select $1 from ' || quote_ident(sel_tblname) ||
>

This deletes rows from the table depending only upon finding at least one
row in the subquery - the limit is basically pointless.  Since all rows
return the value provided in $1, and $1 = $1.

So these indeed produce different results, as they should.  The "error" one
is behaving exactly as it should.  If it doesn't do what you want - which
is likely as it is a very unusual query - don't use it.

David J.