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Up to now we've not worried about whether psql's tab completion queries would work against prior server versions. But since we support older server versions in describe.c, we really ought to do so here as well. Failing to take care of this not only leads to loss of tab-completion service when using an older server, but risks aborting a user's open transaction when we send an incompatible query to the server. The recent changes in pg_proc.prokind are one reason to take this more seriously now than before, and the proposed patch for completion after SELECT needs some such capability as well. Hence, create some infrastructure to allow selection of one of several versions of a query depending on server version. For cases where we just need to select one of several query strings, introduce VersionedQuery and COMPLETE_WITH_VERSIONED_QUERY(). Likewise extend the SchemaQuery infrastructure to allow versioning of those. I went ahead and fixed the prokind issues, to serve as an illustration of how to use versioned SchemaQuery. To have some illustration of VersionedQuery, change the support for completion of publication and subscription names so that psql will not send sure-to-fail queries to pre-v10 servers. There is much more that should be done to make tab completion more friendly to older servers, but this commit is mainly meant to get the infrastructure in place, so I stopped here. Discussion: https://postgr.es/m/24314.1520190408@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/.