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There are a few things that we could do a little better within get_cheapest_group_keys_order(): 1. We should be using list_free() rather than pfree() on a List. 2. We should use for_each_from() instead of manually coding a for loop to skip the first n elements of a List 3. list_truncate(list_copy(...), n) is not a great way to copy the first n elements of a list. Let's invent list_copy_head() for that. That way we don't need to copy the entire list just to truncate it directly afterwards. 4. We can simplify finding the cheapest cost by setting the cheapest cost variable to DBL_MAX. That allows us to skip special-casing the initial iteration of the loop. Author: David Rowley Discussion: https://postgr.es/m/CAApHDvrGyL3ft8waEkncG9y5HDMu5TFFJB1paoTC8zi9YK97Nw@mail.gmail.com Backpatch-through: 15, where get_cheapest_group_keys_order was added.
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/.