
This patch ensures that, if any notify messages were received during a just-finished transaction, they get sent to the frontend just before not just after the ReadyForQuery message. With libpq and other client libraries that act similarly, this guarantees that the client will see the notify messages as available as soon as it thinks the transaction is done. This probably makes no difference in practice, since in realistic use-cases the application would have to cope with asynchronous arrival of notify events anyhow. However, it makes it a lot easier to build cross-session-notify test cases with stable behavior. I'm a bit surprised now that we've not seen any buildfarm instability with the test cases added by commit b10f40bf0. Tests that I intend to add in an upcoming bug fix are definitely unstable without this. Back-patch to 9.6, which is as far back as we can do NOTIFY testing with the isolationtester infrastructure. Discussion: https://postgr.es/m/13881.1574557302@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/.
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