5ac9c43073
There was some code in gen_prune_steps_from_opexps that needlessly checked a list was not empty when it clearly had to contain at least one item. This prompted a further cleanup operation in partprune.c. Additionally, the previous code could end up adding additional needless INTERSECT steps. However, those do not appear to be able to cause any misbehavior. gen_prune_steps_from_opexps is now no longer in charge of generating combine pruning steps. Instead, gen_partprune_steps_internal, which already does some combine step creation has been given the sole responsibility of generating all combine steps. This means that when we recursively call gen_partprune_steps_internal, since it always now adds a combine step when it produces multiple steps, we can just pay attention to the final step returned. In passing, do quite a bit of work on the comments to try to more clearly explain the role of both gen_partprune_steps_internal and gen_prune_steps_from_opexps. This is fairly complex code so some extra effort to give any new readers an overview of how things work seems like a good idea. Author: Amit Langote Reported-by: Andy Fan Reviewed-by: Kyotaro Horiguchi, Andy Fan, Ryan Lambert, David Rowley Discussion: https://postgr.es/m/CAKU4AWqWoVii+bRTeBQmeVW+PznkdO8DfbwqNsu9Gj4ubt9A6w@mail.gmail.com |
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| README.git | ||
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README
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/.