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d747dc85ae
A refcursor variable that is bound to a specific query (by declaring
it with "CURSOR FOR") now chooses a portal name in the same way as an
unbound, plain refcursor variable. Its string value starts out as
NULL, and unless that's overridden by manual assignment, it will be
replaced by a unique-within-session portal name during OPEN.
The previous behavior was to initialize such variables to contain
their own name, resulting in that also being the portal name unless
the user overwrote it before OPEN. The trouble with this is that
it causes failures due to conflicting portal names if the same
cursor variable name is used in different functions. It is pretty
non-orthogonal to have bound and unbound refcursor variables behave
differently on this point, too, so let's change it.
This change can cause compatibility problems for applications that
open a bound cursor in a plpgsql function and then use it in the
calling code without explicitly passing back the refcursor value
(portal name). If the calling code simply assumes that the portal
name matches the called function's variable name, it will now fail.
That can be fixed by explicitly assigning a string value to the
refcursor variable before OPEN, e.g.
DECLARE myc CURSOR FOR SELECT ...;
BEGIN
myc := 'myc'; -- add this
OPEN myc;
We have no documentation examples showing the troublesome usage
pattern, so we can hope it's rare in practice.
Patch by me; thanks to Pavel Stehule and Jan Wieck for review.
Discussion: https://postgr.es/m/1465101.1667345983@sss.pgh.pa.us
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download/ See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.