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Commit 4a4e6893aa080b9094dadbe0e65f8a75fee41ac6, which introduced this mechanism, failed to account for the fact that the RECORD pseudo-type uses transient typmods that are only meaningful within a single backend. Transferring such tuples without modification between two cooperating backends does not work. This commit installs a system for passing the tuple descriptors over the same shm_mq being used to send the tuples themselves. The two sides might not assign the same transient typmod to any given tuple descriptor, so we must also substitute the appropriate receiver-side typmod for the one used by the sender. That adds some CPU overhead, but still seems better than being unable to pass records between cooperating parallel processes. Along the way, move the logic for handling multiple tuple queues from tqueue.c to nodeGather.c; tqueue.c now provides a TupleQueueReader, which reads from a single queue, rather than a TupleQueueFunnel, which potentially reads from multiple queues. This change was suggested previously as a way to make sure that nodeGather.c rather than tqueue.c had policy control over the order in which to read from queues, but it wasn't clear to me until now how good an idea it was. typmod mapping needs to be performed separately for each queue, and it is much simpler if the tqueue.c code handles that and leaves multiplexing multiple queues to higher layers of the stack.
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: http://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 http://www.postgresql.org/download/. For more information look at our web site located at http://www.postgresql.org/.